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Physical Geology

by: Ms. Ellie Durgan

Physical Geology GEOL G1110

Marketplace > Purdue University > Geology > GEOL G1110 > Physical Geology
Ms. Ellie Durgan
GPA 3.7


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This 58 page Class Notes was uploaded by Ms. Ellie Durgan on Saturday September 19, 2015. The Class Notes belongs to GEOL G1110 at Purdue University taught by Staff in Fall. Since its upload, it has received 70 views. For similar materials see /class/207995/geol-g1110-purdue-university in Geology at Purdue University.


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Date Created: 09/19/15
The AS1 Seismograph Magnitude Page 1 of 22 The ASl Seismograph Magnitude Determination L W Emilequot November 2002 Updated April 30 2006 nu hs xplorations in ni t39il l i ll lt l llll l l l Earth Science uma ng Earthquake Magnitude from As1 Seismograms Magnltude ls an estarnate of the energy release or Size of an earthquake Magmde estarnates are e selsmograph stahon from the earthquake Seismic waves spread out and are absorbed dunng rop ahon and thus enerally beeorne smaller at greater dis s orn the earthquake epleenter and he arnph eahon of the signal by the selsmograph Magm de f l h b en devel d t es of selsmograph ally dependent on the frequency response of the selsm graph and dlfferent type of Seismic amvals body waves and surface waves Usually the formulas are valld f0 a eertaln range of epleenter to statlon dlstanees or reglon for example Rlehter magmde was developed for Callfomla and for earthquakes of parheular depths for example surface formulas are lnaeeurate for very large earthquakes Addhonally magmde formulas have been developed over tarne as lns rurnen s ave ehanged and more data have beeorne avallable Generally rnagnltudes should be deterrnlned form arnphtudes measured on before rneasunng arnphtudes one should seleet cutoff frequencles for the lter that plaee the typlcal frequency for the magmde deterrnlnataon about 0 5 e for body waves an 0 0 waves a ro rnl e n rrn magnltudes and lntenslty magnitude and lntenslty are e eonfusede rnagnltude ls a measure of the size ofthe earthquake lntenslty ls the level ofground shaklng at a specific loeataon ean be foundm Bolt 1993 1999 and at the followlng web sltes neleus s ovnels eneralhandouts eneral selsrnlel htrnl www selsrno unr edutt ublouleelassloorna nltude htrnl Capynghtl rl L Ernle Pemllsaangamedexepxadumanfaxnanrcammel39clalpurpases xplorations in Earth Science The AS1 Seismograph Magnitude Page 2 of 22 laskerprlneeton eduSeleneePro eetseurreqmggeqmgg htm http www eas slu eduPeoplecJAmmonHTMlclassesIntxog akesNotesearthquake slze html http www selsmo eommsopnmsop0320soureesouree4souree4 html Currently m an effortto reduee eonfusron about earthquake magnrtudes and use the most relrable measure of earthquake srze most magnrtudes reported by the Us Geologreal Survey t Hearth uake us s ov are abe ed M nrtudequot or and are moment magmde someumes referred to as MW determrnatrons when avalla e Howev tradmonal magnrtude determrnauons sueh as body wave magnrtude mb surfaee wave magnr MS and Lg wave magnrtude mbLg are also reported m USGS earthquake eatalogs Determrnauons of magnrtude for these magnrtude defrnruons ean be made usrng data from the A31 sersmograph The proeedure for determrnrng magnrtude from sersmograms reeorded by the AS sersmograph ls From the AmaSels software determrne the appromma amval ume of th earthquake prossrble prek the P and S arrrvals frltenng the se m g am may help m the rdenufreauon of the S wave and estrmate the dstanee usrng the travel ume eurve tool Usrng the seleeuon tool 2 om m on the P wave entraet the early part of gram the trme expmslon tool at the bottom left of the sereen may zoomlng m on the P arnv and determrne the n eounts and the apprommate penod of the e The P arnval may rnelude frrst apprommately 10 s of the reeord Often a dlstlnct s or PP wlll be present after the frrst P arrrval Esumate n seeonds between two e e seale held up to the sereen ls usefu tool entraet the early usually largest part of the surfaee wave e the sersmo useful for to peak r m am P wave Use the largest amplrtude ofth P w ve energy that oeeurs dunng the eeondary P phase sueh as pP the penod b measunng the S lt E 8 9 a a we a g E am surfaee wave arrrval that ls near 20 s penod Note the perrod of the surfaee wave where your amplrtude measurement ls made Seareh under the Qulek Llnks menu at le slde of sereen or for reeent even s t the USGS earthquake slte tm earthqu eusgs gov sel Latet akes an then N39EIC errent Earthquake Informataon or the IRIS ls re Monltor tool www lns edu and frnd andreeord the of clal ongrn trme loeauon latrtude and longrtude note S lautudes and w longrtudes are negauve and d and magnrtude Several magnrtude estrmates may be avallable oeeurred at least a week earller the IRIS event seareh tool ean be used to nd xplorations in Earth Science The AS1 Seismograph Magnitude Page 3 of 22 for example p be Mw moment magnrtuole whreh eannot be estrmateol from Asel reeorol but b The In r geographre olesenptron of the earthquake loeauon that ls often useful Go he USGS travel tame and drstanee ealeulatron srte thnereusgsgovnerstrayel umeso anol ealeulate the drstanee from our selsmograph statron t the earthquake epreenter by entenng the lautuoles and e olthe b the lautuole anol longrtuole of your st topogr map and use the tools to frnol a speerfre loeauon at www mapteeh eom elrek on onlrne Maps seleet the Ma Seryer then enter erty and state m the boxes and elrek go seleet eorreet map from lrst rf lrst of possrble maps appears ehoose DD DD m dlsplay to the left of the map For rnterest you ean eompare the ealeulateol the P and s arnyals 5 4 me m AmaSels 3 Uslng the Amplrtuole stanee penool anol drsplaeement amplrfreatron read from the table proyroleol m the eomputer eoole below olata ealeulate the magnrtuole estrmates for the earthquake The ealeulatrons ean easrly be maole wrth a hanol e u a or or eh as e Matlab eoole an su th n below Note that yahol data from the magnrtuole formulas wlll usually be resmeteol to ertarn drstanee ranges Compare the magnrtuoles oletermrneol from yourASel selsmogram wrth the offlclal magmde esumates Magmde formulas a table of amplrfreatron rnformauon for the Asel selsmograph amplrfreauon yersus penod and a sample Matlab eomputer eoole that es the amplrtuole drstanee penool drsplaeement amplrfreatron olata anolthe magmde formulas to ealeulate magnrtuole estrmates ls shown below eleuleee magnneuuea in Ase Selsm grams urenle puruue Unlversltvr 122Buu revlsed u117u1 c L r a e Emphcude lzeru eu peekl 1n euunea u ehe errwel un Ase r n e dlscance 1n dEgrees lgeucenene angle une uegree 11119 mm un r T perlud let u ehe errwel lmeeaure by dlscance heeueen euu neeksl r Velamp veluem Empllilcaclun u Ase 1n euunearmeruna u x As 1 r ma 1sp1eeemene ampl 1eee1un u e 1n euunearmerun r maamp VelemnmpzT r A e u1sp1eeemene ampllcude e emaemn lm1erunsl xplorations in Earth Science The AS1 Seismograph Magnitude Page 4 of 22 T551e 5 5mp111eer15n versus per15d 5r the 551 se1sm5grepn per15d T rregueney Ve1 555111eer15n 51551 Amphilcaclun 5 51 um DDuncsmlchnSY LDDuncsmlcrum 5 1 1 12 75 5 15 5557 22 52 5 2 55 25 55 5 3 5333 25 55 5 5 52 22 25 5 15 51 5 57 5 15 55557 1 17 5 25 5 55 2 553 5 35 5 333 57 515 5 5 52 515 551 5 155 5 51 552 55513 5 change 5 5 T and 51s5mp 5r eeen calculaclun 5 Reed 51s5mp r5n cable 555ve 5r 5ppr5pr1ere per15d T 5 Use n5gn1rude esr1nere nah 55 n55g1 5r mthZ 5ppr5pr1ere r5 dare 5 55re dlscance r5nges 5nd 5ppr5x1nere per15d niurmaclun 5r eeen 5 n5gn1rude 5rnu15 55gn1rude Equacluns 5re r5n 551 L 555 5r mh 5 5nd 5555551c 5r 55 and mth 555111eer15n 5er5rs are 5 r5n 55e1 55115r5515n der5 pr5v1ded by Tlm 55ng Geurgla Teen 5 nernruguekee5sgereenedu5555e5c515enrrx5e1nrn 5 555 Hut 5555 515uguerguey e15r11ed the use 5 the 5mp111eer15n 5 5er5rs 1n the m5gn1rude 5rnu15s sampF JDQJDLAT 5 25 deg lt 5 lt 55 deg 55155 55 T1ea s 5 e JDQJDLAT 66lug1 lm 33 5 25 deg lt 5 lt 155 deg T2EI s n55g1 JDQJDLAT D9Dlug1 lm 375 5 55 eg lt 5 lt 5 deg T1 s mhL 2 JDQJDLAT 155515g15m 33 5 5 d lt 5 lt 35 deg T1 Magnitude Calculator A new onlme rnagnrtude calculator for the A551 sersrnograpn rs avatlable at nagmemes gurdue edubraleedumodNIagCalcnggc chtm The calculator ean be used to calculate rnb MS and mbLg rnagnrtudes from A551 amphtude data The 5 rs also possrble to use these equauons to perform the ea1eu1auons thh a srrnple e1eeaonre calculator by handquot n 51st Updates A ew versron of ArnaSers 1 www sol bm hamton edufacul ones mcludes are abthty to easrly determan urne and amplxtude on an 5 t sers ample e Septem r 25 2003 M80 Hokkardo Japan earthquake Frgure 1 are extracted sersrnograrn a er xplorations in Earth Science The AS1 Seismograph Magnitude Page 5 of 22 se1eeaon wrth the eursor on the 24rhour sereen duplay or from opemng a premously saved sae le rs shown wrth an aetua1 UTC trme sea1e below the sersmogram In The rst of these wrndows duplays the aetua1 UTC ame assumrng that the eomputer39s clock has been synehronrzed wrth UTC me of the posraon of the eursor honzontat posraon on the sereen and the seeond wrndow shows the amphtude m dAngal unrts of the eursor of amvals on the sersmogram and amphtudes of the amvals for magnrtude eateulatron When measunng amphtudes rt rs neeessary to not the posraon of the apprommate zero hne on the sersmogram If the reeorded srgnats are eentered on the zero hne then no peak used for the magnrtude measurement should be measured from the posrtron of the srgnat a sm all number of dAngal unrts and the v A571 AmaSers tame and amphtude measunng tool are shown m Frgures 1 2 and 3 Fugue 1 AmaSet Eumayam fb the MK 5 September 25 2005 Holdalde Japan Earthquake xplorations in Earth Science The AS1 Seismograph Magnitude Page 6 of 22 M 1 w W A in M f t u t h t 1 Mt U W M U M h t 39 W W mum muenquun gAm 2 Enlarged Elected m Ahegeu etmegmh far the p wavy amval far the MK 5 September 25 2005 Haldmxda Japan emthqeehe recorded 41 Wet La tyene Indmm m the In th 5412 a ehettt 20 05 05 I meemed For duteht evehtx the u ameg Energy I eteh pread out we 1015261md Far 5102 Ewnfr the mayhem amphde afthe rxt arnvmgP phaxe t eteh wtthm the at 2 eczmd efthe amval m Ila Ewm eh amphde af223 the Epicenterrhxxmnan mtahee t 35 07 degree Unng thexe 11112 the A571 maghttude far Ila wentdetermmed am eh average Dfmawyxmxmayaph mmm xplorations in Earth Science The AS1 Seismograph Magnitude Page 7 of 22 l a an F lgAm 5 MR 5 SeptemberZS 2005 Haldmldu Japan Earthquake recorded a West La zyslls Inalana FD the m nagnllaaa salmlanun the mannan anphluaa uflns 1022 Ecand mr zce wave l neaswsa mm m the AmaSEX al wam The Eplcemerrhxxmnan axslance x 35 07 deyeex Lhng these values the A51 magmude calculator returns a salmlalsamnagnltaas W 0 comparedta tns a inal usss MS nagnltuaa of 7 5 far tnls stunt determng lm an awnaga bf nany mxmayaph mmm Example Magnitude Calculations for ASrl Seismograms Examples ofASr l selsmograms and magmde ealeulatlons are glven below Flgure 4 shows a 24 hour ASrlAmaSels sereen dlsplay of selsrnle olata mcludmg the August 4 2000 Sakhalln VT F n del w a and surface waves are Vlslble The extraeteol selsmogram for the Sakhalln Island event ls shown ln Flgure 5 A e oserup Vlew of the P wave amval ls shown ln Flgure o The rnalrlrnurn arnplltuole of the P wave ls about 70 eounts andthe penool of the Wave energy ls about 2 s The alstanee from the epleenter to the selsmograph determlneol from the laatuoles and longltuoles of the epleenter and stataon usln the htt neleus s ovnelstravel tarnes slte ls 8108 degrees The alsplaeernent xplorations in Earth Science The AS1 Seismograph Magnitude Page 8 of 22 amph cauon of the A571 sexsmograph for a 2 s penod 15 88 countsmicron one micron 15 one mmmnm of ameter So forthe following data a 70 counts T2amp D 108 degrees Dispamp 88 countsmxcron so A astamp 7088 mmrons andthe body wave formula m1 Iag10A77 001 D 59 the magmmde 15 mb s 3 Tth magmmde 15 the same as the of cial USGS magmmde ofmb s 3 Fugue lt1 AmaSex 2 hr mmmlmclw ngthe Aug lt1 2000 51mm leand Earthquake xplorations in Earth Science The AS1 Seismograph Magnitude Page 9 of 22 WWWMMWWMM Fxgme 5 Sexsm g mfmthe Salwalm Island Earthquakz xplorations in Earth Science The AS1 Seismograph Magnitude Page 10 of 22 t 39l t v t M M t l My tht t tttt r M H t t quot 39 r t t Fig 5 Seumagmm for the stdaraer hmd mnhqwzky stamp afthe to 01mm A closeeup vrew of the surface waves for the Sakhalm Island everrt rs shown m Frgure 7 Usmg the followmg data for the surface Wave amval 0 eourrts s D e 8108 degrees Drsarhp 0 63 eourrtsrrrrerorr so A aDrsarrrp 600 63 rhrerorrs arrdthe surface wave formula MS1ag10A77 1m1dg1on 33 the ealeulatedmagmtude rs MS 7 1 the same as the USGS magmtude of MS 71 xplorations in Earth Science The AS1 Seismograph Magnitude Page 11 of 22 A mm Fugue 7 An addmonal example of body Wave and surface Wave magmmde calculations 15 r Lu June V 000 xplorations in Earth Science The AS1 Seismograph Magnitude Page 12 of 22 Fugue K AmaSex 201w Eumx mmdmclmttgme lime 21 zooolceland Earthqualaz A closeeup mew of the P wave for the Iceland event is shown m gure 10 Usmg the followmg data for the P wave amt11 a so eouhts T 1 5 s D 44 23 degrees Disamp 92 countsmicron so A aDlsamp 6092 microns andthe body wave formula m1 Iag10A77 001m 59 the magmtude ls mb s 0 comparedto the USGS magmtude ofmb 61 xplorations in Earth Science Seismograph Magnitude ya 13 of WW WWWWI M The AS1 Seismograph Magnitude Page 14 of 22 11111 1 1 1 1 MM P111111 UN 1 1 5 1 1quot1 11quot L f 11 1 15 1quot 1 gAm 10 Sexsmagmm fmme Iceland Earthquake staseeup afthe Pamval A closerup mew of the surface waves for the Iceland event 15 shown m Fxgure 11 Usmg the following data forthe surface Wave amval 20 eoums 5 s T D 44 23 degrees Disamp 17 countsm1ronso A astamp 12017 microns andthe surface wave formula MS1ag10A77 1 1ag10D 33 the calculatedmagmtude 15 MS 6 7 comparedto the USGS magmde of MS 6 6 xplorations in Earth Science The AS1 Seismograph Magnitude Page 15 of 22 G 1mm r quot muurrr Agave 11 Sermgmm lthy Iceland earthquake 51112411 ofthe w zce wave amval An example of ealeulatmg magmtude for a deep foeus earthquake m vvhreh surfaee vvaves are gerrerally very small so that the surfaee vvave m rutud f la e not be used ls shown m Flgures 1213 and 14 The formula used here and m the Matlab eode above ls a srmplrfred formula m vvhreh ho eorreetroh ls made for the dep t e earth 011 l d th USGS rutude al l u hs mb eal latrorrs for deeper earthquakes melude a eorreetrorr for the effeet of dep A deserrp ls proeedrre and the graph h f etor at s owmg eorr a s ls grverr httpvava sersmo eommsophmsop0320soureesouree4souree4 html Flgure 12 shows an AmaSels sereeh drsplay for the May 12 2000 sersmre data The reeord The extraeted sersmogram for thrs everrt ls shown m Flgure 13 Notree that although ere are very strong P vvaves hear the begrrmmg of the srghal the surfaee vvaves vvhreh shouldbegm about 17 mmutes a er the frrst arrrval for thrs drstarree are abserrt A closer up vrevv ofthe P vvave for the Argehuha xplorations in Earth Science The AS1 Seismograph Magnitude Page 16 of 22 Rwy 12 AmaSex 2 ham mxmx record xncludmg the My 12 2000 Argemmz Bantam0 xplorations in Earth Science The AS1 Seismograph Magnitude Page 17 of 22 WWWMWrMMWN MWWAMn w m an un In an In m H x n u m h gAm 1 Seumayam funky deepfam Argennm Earthquake event 5 shown m Fxgure 14 Usmg the followmg data for the P Wave amval a 150 counts T Disamp 88 countsmicron so A astamp 15088 microns andthe body wave formula m1 Iag10A77 001m 59 the magnitude 5 mb s 5 comparedto the USGS magnitude ofmb s 2 xplorations in Earth Science The AS1 Seismograph Magnitude Page 18 of 22 t W 11 M 11 1 H t 1quot t 391 1 hquot WNW 1511 1 t W gAm m Seumagam fan he Argennm Earthquaky closeup afthe p ammz The calculation of the mbLg magmde eah be xllustxated with the hegmha event from gure 15 Evahsmue 1N earthquake The mbLg magmtude 15 used most often for 1 0th Amenca 1h thxs case the maximum amphtude of the shear and surface Wave arnvals near 175 mmutes relative hme tn the selsmogram 1h gure 15 15 used Using the honzonta1 eomponeht observations arma1 5 eouhts 0 s D e 2 sideghees Disamp 75 countsm1ronso A astamp 2575 means and the mbLg formula thth 1ag10A77 090Iag10D 375 xplorations in Earth Science The AS1 Seismograph Magnitude Page 19 of 22 M I r Wft hjl l tt l l l q l Jaw H mm Dummy gure 15 A West Lafayette new eventrue Mam December 7 2000 The earthqualaz Epwenler W01 01me 292 km away lm the sesnngmph and had a magmtude 501me 3 9 mbLg Memsersms nfadenl sets fallawmg the F wave A m anson of m mtudes ealeulated from ASrl selsmograph data usmg the proeedures desenbed here wth USGS magmtudes ls shown m Flgure 16 Kt m m e esumates agreed perfeetly the data would plot on the dlagonal hne Thls eompanson suggests that earthquake magmtudes ean be determrned from ASrl selsmograph reeords wrth an aeeuraey of about r 0 5 magmtude umts 95 con dence hmrts Some varratron m magmtude estrmates ls expeeted b stauons are loeated on dlfferent geologreal matenals varratron m srte response the a an m ra a on pa m of selsml waves generated by earthquakes beeause selsml waves are eaused by release of energy assoerated wth shp along a fault plane wth a specl c tatron en y ls not propagated equally m all dlreeuons there ls varratron m the ampllflcatlon of sersmographs an amphtude and penod measurement on the selsmogram ls subjectto some rnterpretauon and error h we eannot ealeulate moment magmtude MW or slmpl M from ASrl sersmograms the A54 magmtudes mb MS and mbLg provlde reasonably aeeurate estrmates owa Flgure 17 xplorations in Earth Science The AS1 Seismograph Magnitude Page 20 of 22 Comparison of AS1 and USGS Magnitudes AS1 Magnitude 07 x JV 0 c8 3 9 mb magnitudeso MS magnitudes a 3 0 0 r7ng magnitudes o 8 Q1 4 5 6 7 USGS of cial Magnitude MW 15 Companmm of magmmaa for aanhqaaa recorded 5 an A51 mmg calculated am aph g the procedure and formula gven m the text and the uses mag mde determxmnon farthe Earthquake Damfwm Jammy 1 200mm mm 51 2006 xpiorations in Earth Science The AS1 Seismograph Magnitude Page 21 of 22 r n 1 mbLgY 4 a 0 8 MS magnitudes O Q m 7 o 3 ma magnitudes a 0 m 39E m In 6 E o o 039 lt o 5 O o O O 4 mbLg magnitudes 0 0 5 6 7 USGS of cial Mw M agnitude Fugue 17 Campmmm afASel mammde mbLg mb andV157 thh USGSMW magmude References Bolt B A Eathqualws and Gealagxcal stcavery Smenufx Amenean Library WH Freeman New York 229 pp 1993 Bolt B A Earthquakzs 4 h admon WH Freeman amp Company New York 364 pp 1999 xpiorations in Earth Science The AS1 Seismograph Magnitude Page 22 of 22 Return m Braile s Earth Science Edncztinn Animus gage Rama Pages The A871 Seismngzgh 7 Installatinn and Ca hrz nn Th A871 Seismnglzghr Ugandan Filtering s712 Distance Calculatinn and Ideas 2 far Classrnnm Use xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 1 of 36 the I Seismic Waves W i i quot m o W W and the Slmky A Guide For Teachers v23 December 2000 last updated March 2006 CONSORTIUM Prof Lawrence W BraiIeQ Department of Earth and Atmospheric Sciences Purdue University West Lafayette IN 479072051 braile urdueedu webicspurdueedubraile xpforations in Earth Science Objectives This teaching guide is designed to introduce the concepts of waves and seismic waves that propagate within the Earth and to provide ideas and suggestions for how to teach about seismic waves The guide provides information on the types and properties of seismic waves and instructions for using some simple materials 7 especially the slinky 7 to effectively demonstrate seismic wave characteristics and wave propagation Most of the activities described in the guide are useful both as demonstrations for the teacher and as exploratory activities for students With several regular metal slinkys and the modified slinky demonstrations described in this teaching guide one can involve an entire class in observation of the demonstrations and experimenting with the slinkys in small groups For activities that involve several people such as the 5slinky and human wave demonstrations it is convenient to repeat the demonstrations with different groups of students so that each person will have the opportunity to observe the demonstration and to participate in it Waves Waves consist of a disturbance in materials media that carry energy and propagate However the material that the wave propagates in generally does not move with the wave The movement of the material is generally confined to small motions called particle motion of the material as the wave passes After the wave has passed the material usually looks just like it did before the wave and is in the same location as before the wave Near the source of a strong disturbance such as a large explosion or earthquake the wavegenerated deformation can be large enough to cause permanent deformation which will be visible as cracks fault offsets and displacements of the ground after the disturbance has passed A source of energy creates the initial disturbance or continuously generates a disturbance and the resulting waves propagate travel out from the disturbance Because there is finite energy in a con ned or shortduration disturbance the waves generated by such a source will spread out during propagation and become smaller attenuate xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 2 of 36 with distance away from the source or with time after the initial source and thus will eventually die out Waves are o en represented mathematically and in graphs as sine waves or combinations or sums of sine waves as shown in Figure l The vertical axis on this plot represents the temporary motion such as displacement amplitude A of the propagating wave at a given time or location as the wave passes The characteristics or properties of the wave 7 amplitude wavelength peaks etc 7 are illustrated in Figure l quertiescfasinevae yA n2nft Freql lenq f 17 Figure 1 Properties of a sine Melergm A wave The horizontal axis 1 or Reriod 739 M displays time or distance and gt the vertical axis displays lt amplitude as afunction of g time or distance Amplitude can represent any type or g mm X measure of motion for any or Tme 139 direction Seismic wave motion is commonly displayed with a similar plot and sometimes the wave itself Trough looks very similar to the sine wave shown here Additional information on the properties of waves can be found in Bolt 1993 p 2930 or Rutherford and Bachmeyer 1995 Sometimes the actual wave looks very much like the representation in the graph Figure 1 Examples are water waves and a type of seismic surface waves called Rayleigh waves Commonly propagating waves are of relatively short duration and look similar to truncated sine waves whose amplitudes vary with time Waves generated by a short duration disturbance in a small area such as from an earthquake or a quarry blast spread outward from the source as a single or a series of wavefronts The wavefronts at successive times and corresponding raypaths that show the direction of propagation of the waves are illustrated in Figure 2 A good model for illustrating wave motion of this type is water waves from a pebble dropped in a still pond or pool The disturbance caused by the pebble hitting the surface of the water generates waves that propagate outward in expanding circular wavefronts Because there is more energy from dropping a larger pebble the resulting waves will be larger and probably of different wavelength xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 3 of 36 Wavef fonts an d Ray paths in Figure 2 Wavefronts anal raypaths for a Seismic Wave Propagation seismic wave propagating from a source Three positions successive times of the expanding wavefront are shown Particle motions forP compressional anal S shear waves are also shown Raypaths are perpendicular to the wavefronts anal indicate the direction of propagation of the wave P waves travel faster than S waves so there will be separate wavefront representations for the P anal S waves If the physical properties of the material through which the waves are propagating are constant the wavefronts will be circular or spherical in three Shea s 4 dimensions If the physical properties vary monoquot in the model the wavefronts will be more complex shapes Compressional P motion Waves in Water Experiment Experiments with water waves in a small wave tank consisting of a rectangular plastic storage box about 60 to 120 cm long by 40 cm wide by 15 cm high the exact size isn t important a plastic storage box designed to fit under a bed available at discount department stores such as KMart WalMart and Target with about 5 cm of water in it can easily illustrate the common properties of water waves Figure 3 Drops of water from an eyedropper or small spherical objects a table tennis ball a golf ball or a small rubber ball works well dropped onto the surface of the water are convenient sources With the wave tank one can demonstrate that the size amplitude of the waves is related to the energy of the source controlled by the mass and drop height the waves expand outward propagate in circular wavefronts the wave height decreases and eventually dies out with distance away from the source or with time after the source because of spreading out of the wave energy over a larger and larger area or volume the waves have a speed velocity of propagation that can be measured by placing marks every 10 cm on the bottom of the tank and timing the wave with a stopwatch the waves re ect off the sides of the tank and continue propagating in a different direction after re ection About 34 small oating ags can be used to more effectively see the motion of the water as the wave passes The ags are particularly useful for noting the relative amplitude of the waves as the degree of shaking of the ags is a visible indication of the size of the wave Flags can be made from small pieces 2x2xl cm of closed cell foam styrofoam or cork Place a small piece of tape on a toothpick and stick the toothpick into the foam or cork to create a oating ag Figure 4 that is sensitive to waves in the water By placing the ags in the wavetank at various distances from the source one can easily observe the time of arrival and the relative amplitudes of the waves A glass cake pan Figure 5 can be used as small wave tank on an overhead projector Waves generated by dropping drops of water from an eyedropper into about 2 cm of water in the tank will be visible on the screen projected from the overhead projector The xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 4 of 36 velocity of propagation attenuation of wave energy and re ection of waves are important concepts for understanding seismic wave propagation so experimenting with these wave properties in the water tank is a very useful exercise Additional suggestions for experiments with water waves are contained in Zubrowski 1994 Figure 3 Large wave tank using a plastic storage container 75 liter quotunder bed quot container Distances in cm can be marked on the bottom of the container for convenient measurement of wave velocity from the distance and travel time Small oating ags Figure 4 are useful for identi ving the time anal relative amplitude of propagating water waves The flags are made from small oats about 2x2x1 cm rectangular blocks of closed cell foam Styrofoam or cork with a toothpick and piece of tape attached The oating ags are very sensitive to wave motion in the wave tank In this sequence of photos taken every one half second one can see the waves propagating outward from the source Lines drawn on the bottom of the tank are spaced at 10 cm A Source a table tennis ball dropped from about 40 cm height is just ready to hit the water surface B N 05 s after the xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 5 of 36 source Water waves have propagated from the source to about 10 cm distance A circular expanding wavefront is visible and the wave height is larger than in the later photos C N 10 s The wavefront has propagated to about 20 cm distance and the waves have decreased in amplitude D N 15 s The wavefront has propagated to about 30 cm distance E N 2 s The wavefront has propagated to about 40 cm distance and the wave amplitudes have decreased so much that they are di icult to see in this photo The small oating ags are sensitive detectors similar to seismometers of the waves Because the waves have traveled about 40 cm in 2 seconds the velocity of propagation is about 20 cms or 02 ms Figure 4 Small oating ags used to help detect the motion of water waves in a wave tank The ags can be quotanchoredquot using a length of thread and a nickel for a weight The ags are sensitive to the motion caused by relatively small waves By noting the degree of shaking of the ags one can identifv approximately large medium and small barely detectible wave action Be sure the water surface is calm and the ags still before initiating a water wave experiment madamusury Iineirsened Float2x2x1an h oat closed cellfoa39nor T 39quot 1 7 7 Figure 5 Small wave tank using a clear glass cake or baking dish The dish with about 2 cm of water in it can be placed on an overhead projector so that wave propagation in the water can be seen on a screen xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 6 of 36 Elasticity Earth materials are mostly solid rock and are elastic and thus propagate elastic or seismic waves in which elastic disturbances deformation or bending or temporary compression of rocks travel through the Earth Elastic materials have the properties that the amount of deformation is proportional to the applied force such as the stretching of a spring as masses are suspended from the spring and that the material returns to its original shape after the force is removed such as the spring returning to its original length after the masses are removed Elasticity of a Spring Experiment An experiment designed to illustrate the elastic characteristics of a spring is shown in Figure 6 Measurements of the stretching of the spring as masses are added and removed are given in Table 1 and graphed in Figure 7 In contrast some materials like most metals are ductile For example if one bends a copper wire it stays bent rather than returning to its original shape One can even make a spring out of copper wire by wrapping the wire tightly around a cylindrical shaped object such as a cardboard tube Repeating the elasticity experiment with the copper wire spring will result in an elastic behavior straight line relationships between the stretching and the amount of mass added for small mass and permanent deformation stretching for larger masses the spring will not return to its original length as masses are removed Data for the copper wire spring experiment can be tabulated as in Table 1 and graphed as in Figure 7 Because this experiment produces a very different stretching versus added mass curve as compared to the regular spring example it is useful to ask the students before the experiment what they expect the results to look like and then compare the actual results with their predictions xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 7 of 36 Measuring Elasticity of a Spring Figure 6 Schematic diagram illustrating mass and spring apparatus for measuring the elasticity stretching of the spring as mass is added of a spring Table 1 Observations of extension of a spring upon adding and removing masses Added Mass Spring Extension cm Spring Extension cm g adding masses gremoving masses 00 0 03 100 37 36 200 77 75 300 114 114 400 153 151 Spring extension stretching is the length of the spring with mass attached minus the length of the spring with no mass Different springs have difkrent spring constants elasticity and will display difkrent amounts of stretching for a given amount of added mass Many springs are tightly wound and require a small amount of force suspended mass to begin extending For these springs one should use the di erence between this initial suspended mass and the total mass as the quotadded mass quot xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 8 of 36 Elasticity of a Spring A16 5 P 5147 Adding mass O D 5 127 Removmg mass i E 10 9 3 8 5 U 6 E g 1 Defamation stretching is m 4 a proportional to applied force mass E 2 Springslums to its olig39nal shape 3 2 a length when force is removed if so 100 250 300 350 400 1 0 Added Mass grams Figure 7 Graph showing measurements of elasticity of a spring Measurements were made as mass was added and removed The stretching of the spring is defined as the spring length with added mass minus the original length Note that the extension versus mass data define a straight line The slope of this line is related to the spring constant or elasticity of the spring The two properties that characterize simple elasticity are described in the figure Seismic Waves Unlike waves in water which are con ned to a region very near to the water s surface seismic waves also propagate through the Earth39s interior Because of the elastic properties of Earth materials rocks and the presence of the Earth s surface four main types of seismic waves propagate within the Earth Compressional P and Shear S waves propagate through the Earth s interior and are known as body waves Figure 8 Love and Rayleigh waves propagate primarily at and near the Earth s surface and are called surface waves Wave propagation and particle motion characteristics for the P S Rayleigh and Love waves are illustrated in Figures 912 Further information and characteristics of these four kinds of seismic waves are given in Table 2 P and SWaves propagation along raypath Earth s surface Seismog raph Pwave particle motion parallel to direction of propagation SH Swave particle motion perpendicular to direction of propagation usually appron39mately in SVand SH directions Z down Figure 8 Raypath from the source to a particular location on the surface for P and S wave propagation in a material with variable velocity P and S particle motion are shown Because major boundaries between different rock types within the Earth are normally approximately parallel to the Earth39s surface S wave particle motion is commonly in the SV perpendicular to the raypath and vertical and SH perpendicular to the raypath and horizontal directions xplorations in Earth Science 853m Scum E 3080qu mmE w Em mgt 2 Egg m cxa SEMEQ EE 2 Eme BEES ER ESESMQRSRKQ 23me 2 E E 9338 953 2 35 an fo mks SEN ERME QEESEkm x0 9333336 w x3 Emiomok wawMS 8 mks MES ERME QEme xBo a E EEQMQRSR E SS mESQEEEE RE 3 m amooxa EQEEE m H B MVESS Q H rm Snme E 23me N mi ES mug Sxmm mi 2 Basing 3m x ES NESEEQ ER 3233 K0 339 a MESEERE NEEM a EMEESS QESMQRSR mgt m EEEEmKQ 3m mEBmREmR m 33 l I u l m u navy 3 1m i u h uv Wom mmm ilitll Ottaho Wkn hth w A 0 nuuuwn llhll39b AV39I Id u n I At l 1 n n it 03 i I 33901 30 39v Aw I I l l D II Iv Di 391 3939 uhafttc hh l I If De uwtoanw tduw t 0 Q AVOOO 01 01 lav A 0 0 39 0 0 lui fitsv 0th onc n m uooo 0 El 1 09 3 0th I 0 l Oh00t0l l 5ihuhvv l tbtthrttt ithuWO u Otto lufltsuw CD 5 O l 1 0 O39QQOO 3w l a l vt ch Vimubhu aonoctI 3000 300 3V1 0 D h it lgnuv kxv l I 0 0 0000 0 in ugduuwv o m 00 0 0O 0 O s 5 000300 ctonynnuu n0 0000 3331 QO Q k A 0 0 III i D kink 04vth lllll 0t 039 d 0 at iiiOtnhvtia ot it ht toat o i t u itttitlbf r 5 33905 01 an O O 005 its O O fllto 1 t O 1 I I xv 9 t 000 T mm ho a wmmn wEsw 95503 555 9 van mwgtmgtgt oEmww w ttt tdi 0 by l I 0005t00 vvthhv h dvt 0005553039 C ltd h i 0 0 i a t 9 t 300 o v o g o t h u Aw 1 0 Au Au 0 5 Aw I ogg 0 Au 39039 Aquot quotO hv 039 39 55 OOODOJO r1 Uhvnv A igh ih lt tnin It a II t z Nt tilgg 39 0 0 Au 01 00000Oll 03r0l0 i k 39 A w quot39 Ottotohiittoiisi v t 0 to 0 0 D 00 O E O D i mv oo 5000 Mu C A39 0 t O u 00 C 00 it On it blottt ldr ilih sit wzhrl quot0004 o An 1 Al t O 00 thumb Iv O l xv 0 00 000i Awquot A hlwquot O i00ttltl hvnh t Nuv00 Ot l OD Suit Otf it Dnuis i D I On xv I 00 000 it 00 0 Di 0 o to o 0 00 co fanny RNQ D tn g a 4 to o ti u 510 v X mm ho 2 wmmn wEsw 95503 555 9 van mwgtmgtgt oEmww Seismic Waves and the Slinky Teacher s Guide Page 11 of 36 1 4 47 ag t 39W a WW I 42437 W w i W 24 9 a t 439 I W A 3 gr I waazagr 5 ivy203 angg a Q a 3x 4 44 f 71 mar 139 a 7 139quot 4 mgquot591 a 1 b 47 q v t giawngf 4 4 439 7 4 w 439h 5 s a quotquotquot 3 y w oquotquot39 39 4 3 e Wze um we i 5 52quot N i I w It Wzu I 4mg v a I quot W Wmee 1 O 5 1a Figure 11 Perspective view of Rayleigh wave propagation through a grid representing a volume of elastic material Rayleigh waves are surface waves The disturbance that is propagated is in general an elliptical motion which consists of both vertical shear perpendicular to the direction of propagation but in the plane of the raypath and horizontal compression in the direction of propagation particle motion The amplitudes of the Rayleigh wave motion decrease with distance away from the surface The material returns to its original shape after the wave has passed xplorations in Earth Science mamaquot ltltmltmm man 5 233 48032 Ocam vmom N o wm lt bxwmn oa 900 u 333 l t00v O 0 1 0 1 500 v 3V 0 O a 00 O it it Q Otit lth ODtb niti t t 0quot 00 0000 3 00 0 i0 0 v Jo0 0l dv O i 395 t In 0 0 h t39 0000 v a 0 EV h i O O O t D l O 390 003 00 thOlO 0 DAV v 039 l 0 a s v 3 O fghvg ti 000 00 A O CO a on Wazucf it 0 0 0 O 31 t 5v 0 O 00 O t Oh vOQ 0 v coon o4 II 00 n mm 3 H A 5an ManWVuonouo aoc nquot Nttvhvg V i 1 ng mnvc 11 oggtc ll 1 l 0 Oni ttivtitf iiuv u a ag 5 u uauoq 90 1 COO it ammmuuwwmwy A DOOOhMuthQOO F g 3 l no to ttil 00 I not l l 9 00 IO 0 0 i O 000 l Vn b 00 a 9405000 0 it 00quot 0 0 DOD30 in 0000quot t t O is 1 00 t v 010 09d 0 39539 39A lvtott tnit l O 01quot I i ii 0 0 OOQODOODOO f it 305 D 3 0 v 0 CO 00 it I t 000 00 O i ii 1 w 00 I II lw I N 8 Int I t tote 11 ca 07 9 hi 9 t I a 0 v0 3 0 t D 000 1 EWSm NM Num mumqm 3mg holtm ltm ESEQWSS 8th a Wig mwxmmmsmsw a lt Nt m Q5 530 333 EOE E33 Sm 25qu EQEM 8 Sh wm qm 1 a ESEQWQRQN a 03833 asuNEQOsumqiax 8 rm Swans Qmmuxo awamos 8 SSVSSNE stwm EOE 33 3320 Roxmgm 3 Nimasqm ESCQQV rm Eqaqm 8 3381mm REE B 5 DENVEN mwa m 83 rm m v5 ESE 33203 3 man mnaanm Seismic Waves and the Slinky Teacher s Guide Page 13 of 36 Table 2 Seismic Waves Type and names Particle Motion Typical Velocity Other Characteristics P Compressional Primary Longitudinal Alternating compressions pushes and dilations pulls which are directed in the same direction as the wave is propagating along the raypath and therefore perpendicular to the wavefront VP N 5 N 7 kms in typical Earth s crust gtN 8 kms in Earth s mantle and core 15 kms in water 03 kms in air P motion travels fastest in materials so the Pwave is the rstarriving energy on a seismogram Generally smaller and higher frequency than the S and Surfacewaves P waves in a liquid or gas are pressure waves including sound waves S Shear Secondary Transverse Alternating transverse motions perpendicular to the direction of propagation and the raypath commonly polarized such that particle motion is in vertical or horizontal planes Vs N 3 N 4 kms in typical Earth s crust gtN 45 kms in Earth s mantle N 2530 kms in solid inner core Swaves do not travel through uids so do not eXist in Earth s outer core inferred to be primarily liquid iron or in air or water or molten rock magma S waves travel slower than P waves in a solid and therefore arrive after the P wave 7 Love Surface waves Long waves Transverse horizontal motion perpendicular to the direction of propagation and generally parallel to the Earth s surface VLN 20 45 kms in the Earth depending on frequency of the propagating wave Love waves eXist because of the Earth s surface They are largest at the surface and decrease in amplitude with depth Love waves are dispersive that is the wave velocity is dependent on frequency with low frequencies normally propagating at higher velocity Depth of penetration of the Love waves is also dependent on frequency with lower frequencies 39 to greater depth R Rayleigh Surface waves Long waves Ground roll Motion is both in the direction of propagation and perpendicular in a vertical plane and phased so that the motion is generally elliptical N either prograde or retrograde VRN 20 45 kms in the Earth depending on frequency of the propagating wave Rayleigh waves are also dispersive and the amplitudes generally decrease with depth in the Earth Appearance and particle motion are similar to water waves Additional illustrations of P S Rayleigh and Love waves are contained in Bolt 1993 p 27 and 37 and in Shearer 1999 p 32 and 152 Effective animations of P and S waves are contained in the Nova video quotEarthquakequot 1990 about 13 minutes into the program and of P S Rayleigh and Love waves in the Discovery Channel video quotLiving with Violent Earth We Live on Somewhat Shaky xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 14 of 36 Groundquot 1989 about 3 minutes into the program and in the animations and activities available at httpWf h 139 HTde Pdquot 39 quot J J WaVeSWavenemn htm Slinky Demonstrations of P and S Waves The P and S waves have distinctive particle motions Figures 8 9 and 10 and Table 2 and travel at different speeds P and S waves can be demonstrated effectively with a slinky For the P or compressional wave have two people hold the ends of the slinky about 34 meters apart One person should cup his or her hand over the end the last 34 coils of the slinky and when the slinky is nearly at rest hit that hand with the st of the other hand The compressional disturbance that is transmitted to the slinky will propagate along the slinky to the other person Note that the motion of each coil is either compressional or extensional with the movement parallel to the direction of propagation Because the other person is holding the slinky rmly the F wave will re ect at that end and travel back along the slinky The propagation and re ection will continue until the wave energy dies out The propagation of the F wave by the slinky is illustrated in Figure 13 Compressional P Wave Propagation In a Slmky Successive Direction of Direction of wave quotmes particle propagation t1 39WW39V WVquot w t3 g is e t4 t5 V v V t6 Com Dilation Com pression pression Figure 13 Compressional P wave propagation in a slinky A disturbance at one end results in a xpiorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 15 of 36 compression of the coils followed by dilation extension and then another compression With time successive times are shown by the diagrams of the slinky at times t1 through t6 the disturbance propagates along the slinky After the energy passes the coils of the slinky return to their original undisturbed position The direction of particle motion is in the direction of propagation Shear S Wave Propagation In a Slinky Successive times Direction of Direction of wave particle propagation motion t2 r P 39 t3 t4 t5 t6 Figure 14 Shear S wave propagation in a slinky A disturbance at one end results in an up motion of the coils followed by a down motion of the coils With time successive times are shown by the diagrams of the slinky at times t1 through t6 the disturbance propagates along the slinky After the energy passes the coils of the slinky return to their original undisturbed position The direction of particle motion is perpendicular for example up and down or side to side to the direction of propagation Demonstrating the S or Shear wave is performed in a similar fashion except that the person who creates the shear disturbance does so by moving his or her hand quickly up and then down This motion generates a motion of the coils that is perpendicular to the direction of propagation which is xpiorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 16 of 36 along the slinky Note that the particle motion is not only perpendicular to the direction of motion but also in the vertical plane One can also produce Shear waves with the slinky in which the motion is in the horizontal plane by the person creating the source moving his or her hand quickly left and then right The propagation of the S wave by the slinky is illustrated in Figure 14 Notice that although the motion of the disturbance was purely perpendicular to the direction of propagation no motion in the disturbing source was directed along the slinky the disturbance still propagates away from the source along the slinky The reason for this phenomenon a good challenge question for students is because the material is elastic and the individual coils are connected like the individual particles of a solid and thus transmit their motion to the adjacent coils As this process continues the shear disturbance travels along the entire slinky elastic medium P and S waves can also be generated in the slinky by an additional method that reinforces the concept of elasticity and the elastic rebound theory which explains the generation of earthquakes by plate tectonic movements Bolt 1993 p 7477 In this method for the F wave one person should slowly gather a few of the end coils of the slinky into his or her hand This process stores elastic energy in the coils of the slinky that are compressed as compared to the other coils in the stretched slinky similar to the storage of elastic energy in rocks adjacent to a fault that are deformed by plate motions prior to slip along a fault plane in the elastic rebound process When a few coils have been compressed release them suddenly holding on to the end coil of the slinky and a compressional wave disturbance will propagate along the slinky This method helps illustrate the concept of the elastic properties of the slinky and the storage of energy in the elastic rebound process However the compressional wave that it generates is not as simple or visible as the wave produced by using a blow of one s fist so it is suggested that this method be demonstrated after the previouslydescribed method using the fist Similarly using this quotelastic reboundquot method for the S waves one person holding the end of the stretched slinky should use their other hand to grab one of the coils about 1012 coils away from the end of the slinky Slowly pull on this coil in a direction perpendicular to the direction defined by the stretched slinky This process applies a shearing displacement to this end of the slinky and stores elastic energy strain in the slinky similar to the storage of strain energy in rocks adjacent to a fault or plate boundary by plate tectonic movements After the coil has been displaced about 10 cm or so release it suddenly similar to the sudden slip along a fault plane in the elastic rebound process and an S wave disturbance will propagate along the slinky away from the source Illustration of Energy Carried by the Waves The fact that the seismic waves P or S that propagate along the slinky transmit energy can be illustrated effectively by using a slinky in which one end the end opposite the source has a small wood block attached The wood block has a cardboard model building attached to it as shown in Figures 15 and 16 As P or S wave energy that propagates along the slinky is transmitted to the wood block the building vibrates This model is a good demonstration of what happens when a seismic wave in the Earth reaches the surface and causes vibrations that are transmitted to houses and other buildings By generating P Svertical and Shorizontal waves that transmit vibration to the model building one can even observe differences in the reaction of the building to the different directions of motion of the propagating wave xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 17 of 36 Cardboard house attached toa slinky to illustrate shaking caused by P and Swaves 8 cm Figure 15 Diagram showing how to attach a E slinky to the edge of a small wood block with K m ilaf lder screws and washers A cardboard quotbuildingquot is ml 2quot attached with tape to the wood block The model 5 8 cm building is madefrom manilafolder or similar material and is taped together The diagram is a side view of the slinky wood block and model building When seismic waves are propagated along the slinky the vibrations of the cardboard building show that the wave energy is carried by the slinky and is transmitted to the model building 9x9x2cm 6 x 12 in screws 316 in washers in i E 3939 Ww t It 1 i Figure 16 Photograph of slinky attached to a small wood block Figure 15 and cardboard quothouse quot The slinky could also be attached to the bottom ot the wood block to illustrate P and S waves propagating upwards and shaking the building xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 18 of 36 Wave Propagation in All Directions An additional demonstration with P and S waves can be performed with the 5slinky model By attaching 5 slinkys to a wood block as shown in Figure 17 5 people can hold the ends of the 5 slinkys stretched out in different directions to about 34 m each One person holds the wood block and can generate P or S waves or even a combination of both by hitting the wood block with a closed st or causing the block to move quickly up and then down or left and then right The purpose of this demonstration is to show that the waves propagate in all directions in the Earth from the source not just in the direction of a single slinky Attaching an additional slinky with small pieces of plastic electrical tape to one of the ve slinkys attached to the wood block makes one slinky into a double length slinky which can be stretched out to 68 m For one of the other four slinkys have the person holding it collapse about half of the coils and hold them in his or her hands forming a half slinky stretched out about 112 2 m Now when a source is created at the wood block one can see that the waves take different amounts of time to travel the different distances to the ends of the various slinkys An effective way to demonstrate the different arrival times is to have the person holding each slinky call out the word quotnowquot when the wave arrives at their location The difference in arrival times for the different distances will be obvious from the sequence of the call of quotnowquot This variation in travel time is similar to what is observed for an earthquake whose waves travel to various seismograph stations that are different distances from the source epicenter Although these two demonstrations with the ve slinky model represent fairly simple concepts we have found the demonstrations to be very effective with all age groups In fact the ve slinky demonstrations are often identi ed as the quotfavoritequot activities of participants Five Slinky P and S Wave Propagation Demonstration 39 washer Figure 1 7 Diagram showing how five slinkys can be attached to the edge of a wood block Photographs of the five slinky model are shown in Figures 18 and 19 When the slinkys are stretched out to different positions five people hold the end of one slinky each and a P or S wave is generated at the wood block the waves propagate out in all directions The five slinky model can also be used to show that the travel times to different locations such as seismograph stations will be different w ales 3963cm apart Woo d block 250m gt xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 19 of 36 To demonstrate this effect wrap a small piece of tape around a coil near the middle of the slinky for one of the slinkys Have the person holding that slinky compress all of the coils from the outer end to the coil with the tape so that only one half of the slinky is extended Also attach an additional slinky using plastic electrical tape to the end of one of the slinkys Have the person holding this double slinky stand farther away from the wood block so that the double slinky is fully extended When a P or S wave is generated at the wood block the waves that travel along the slinky will arrive at the end of the half slinky first then at approximately the same time at the three regular slinkys and finally last at the double length slinky The difference in travel time will be very noticeable Photograph 39 offive slinky model Figure 19 Close up view offive slinky model showing attachment of slinky using screws and washers xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 20 of 36 Human Wave Demonstration P and S Waves in Solids and Liquids This demonstration involves a class or group in simulating seismic wave propagation in solids and liquids If you have 20 or more people in the group half can perform the demo while the other half watches then switch places The concepts that are involved in this demonstration are very dramatically illustrated to the participants Once they have done the human wave activity they should always remember the properties of P and S waves propagating in both solids and liquids Have about 10 people stand at the front of the room side by side with their feet about shoulder width apart Instruct the group to not be too rigid or too limp when pushed from the side They should give with the force that they will feel from the person next to them but not fall over and then return to their upright position In other words they should be quotelasticquot Have a spotter at the end of the line in case the last person begins to fall It is important to stress these instructions to the participants so that the demonstration will work effectively and so that participants do not fall over as the wave propagates down the line of people To represent wave propagation in a solid have each person put their arms over the shoulders of the person next to them chorus line style the molecules or quotparticlesquot of the solid are tightly bonded Push on the person at the end of the line and the deformation leaning to the side and then straightening up will propagate down the line of people approximating a F wave Figure 20 Note that the propagation down the line took some time there is a velocity for the wave propagation and that although each person was brie y subjected to a deformation or disturbance the individuals did not move from their original locations Also the motion of each person as the wave passed was in the direction of propagation and that as the wave passed the people moved closer together temporarily compression and then apart dilation to return to their original positions Figure 20 Human wave demonstration for the P wave in a solid Instructor begins the P wave motion in this case from left to right in the line by pushing compressing on the first person in the 39 i line and then pulling the person back to an upright position For the S wave in a solid make the first person at the end of the line bend forward at the waist and then stand up straight The transverse or shear motion will propagate down the line of people Figure 21 Again the wave takes some time to propagate and each person ends up in the same location where they started even though a wave has passed Also note that the shear motion of each particle is perpendicular to the direction of propagation One of the observers can time the P and S wave propagation in the human wave using a stopwatch Because the shear wave motion is more complicated in the human wave the S wave will have a slower velocity greater travel time from source to the end ofthe line of people similar to seismic waves in a solid xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 21 of 36 37 Figure 21 Human wave demonstration for the S wave in a solid The teacher starts the S wave motion in this case propagating from right to left in the line by causing the first person in the line to bend forward at the waist and then stand up straight Next to represent wave propagation in a liquid have the people stand shouldertoshoulder without their arms around each other Push on the shoulder of the end person and a F wave will propagate down the line The F wave will have the same characteristics in the liquid as described previously for the solid Now make the person at the end of the line bend forward at the waist 7 a transverse or shear disturbance However because the molecules of the liquid are more loosely bound the shearing motion will not propagate through the liquid along the line of people The disturbance does not propagate to the next person because the liquid does not support the shearing motion Compare pressing your hand down on the surface of a solid such as a table top and on the surface of water and moving your hand parallel to the surface There will be considerable resistance to moving your hand on the solid One could even push the entire table horizontally by this shearing motion However there will be virtually no resistance to moving your hand along the surface of the water Only the first person in the line 7 the one that is bent over at the waist 7 should move because the people are not connected If the next person bends sympathetically not because of the wave propagating ask that person if he or she felt rather than just saw the wave disturbance then repeat the demonstration for S waves in a liquid Velocity of Wave Propagation Experiment Developing an understanding of seismic wave propagation and of the velocity of propagation of seismic waves in the Earth is aided by making measurements of wave speed and comparing velocities in different materials For waves that travel an approximately straight line along a straight raypath the velocity of propagation is simply the distance traveled given in meters or kilometers for example divided by the time of travel or quottravel timequot in seconds Using a stopwatch for measuring time and a meter stick or metric tape for measuring distance determine the wave velocity of water waves in the wave tank the F wave in the slinky and the F wave in the human wave experiment Also determine the velocity of sound in air using the following method On a playfield measure out a distance of about 100 meters Have one person with a stopwatch stand at one end of the 100 meter line Have another person with a metal garbage can and a stick stand 100 meters away from the person with the stopwatch Have the person xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 22 of 36 with the stick hit the garbage can so that the instant of contact of the stick with the garbage can is visible from a distance The person with the stopwatch should start the stopwatch when the stick strikes the can and stop it when the sound generated by the stick hitting the can is heard The measured speed of sound will be the distance divided by the travel time measured on the stopwatch This measurement assumes that the speed of light is in nite 7 a reasonable approximation as the actual speed of light is about 3 x 108 or 300 million meterssecond much faster than the speed of sound and that the reaction time for the person operating the stopwatch is about the same for starting the watch when the can is struck and for stopping the watch when the sound is heard The measurement should be repeated a few times to obtain an estimate of how accurately the measurement can be made An average of the time measurements can be used to calculate the sound speed The difference between the arrival of a light wave and associated sound is commonly used to determine how far away a lightning strike is in a thunderstorm For example because the speed of sound in air is about 330 ms if the difference in time between seeing a lightning strike and hearing the associated thunder is 3 seconds the lightning is 1 km away similarly 6 s for 2 km away etc Make a list of the wave velocities in ms for the water waves slinky human wave and sound wave in air Measured wave speeds should be approximately 02505 ms for water waves in a wave tank 2 ms for the compressional human wave 3 ms for P waves in the slinky and 330 ms for sound waves in air Compare these wave velocities with the compressional wave velocity in the Earth which varies from about 1000 ms for unconsolidated materials near the Earth39s surface to about 14000 ms in the Earth39s lowermost mantle 1 to 14 kms The seismic velocity in solid rocks in the Earth is controlled by rock composition chemistry and pressure and temperature conditions and is found to be approximately proportional to rock density density massunit volume higher density rocks generally have larger elastic constants resulting in higher seismic velocity Further information on seismic velocities and a diagram showing seismic velocity with depth in the Earth is available in Bolt 1993 p 143 and Shearer 1999 p 3 Attenuation of Waves To demonstrate the property of anelasticity a model with two slinkys can be constructed Anelasticity is the absorption of energy during propagation which causes waves to attenuate in addition to the attenuation caused by the energy spreading out for example like the spreading of water waves created by dropping a pebble into a pond This effect is an important concept in evaluating earthquake hazards and comparing the hazards in two locations such as the western United States and the eastern United States Seismic waves propagate very efficiently in the eastern United States resulting in damage over a wide area from a large earthquake In contrast waves propagating in the western United States are attenuated by absorption of energy to a much greater degree Thus although earthquakes of a given size occur much more often in the western US the earthquake hazard in the eastern US is significant because the area of damage for equivalent earthquakes is larger in the eastern US Attach two slinkys to a 30 cm long piece of one by two 1 by 2 wood trim using washers and screws Figure 22 similar to that shown in Figure 15 For one of the slinkys place a strip of foam about a 3 m strip of 12 thick foam 7 cm wide the 3 m strip can be pieced together from 23 shorter pieces tape or sew together the strips in the extended coils The foam should fit snugly within the coils and will absorb wave energy that is propagated along the slinky xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 23 of 36 Two slinkys used to demonstrate varying efficiency ofwave propagation due to absorption of energy anelasticity A 39 39 39 39 Museum EC DEDDDDEGUCDH a A A s s mitigaM39lj M etal slinky with strip Two slinkys offoam inside coils Wood blocks attached to with cardboard buildings quot woodblock 3m Figure 22 Schematic diagram illustrating the construction of a model using two slinkys one with a foam strip inside the coils of the slinky that can be used to demonstrate the concept of absorption of energy by material during propagation anelasticity A photo of the slinky model for demonstrating absorption is shown in Figure 23 HWHII l MIquot W l Figure 23 Slinky model used to demonstrate attenuation of waves by absorption of energy7 Small wood blocks and model buildings Figure 15 can be attached to the free ends of both the regular slinky and the foamlined slinky so that the wave energy that reaches the end of the slinky will be more Visible for comparison Extend each slinky about 3 m and cause P or S waves to be xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 24 of 36 generated simultaneously in both slinkys by hitting the wood block for P waves or quickly moving the wood block vertically or horizontally for S waves The regular slinky will propagate the waves very ef ciently while the slinky with the foam will strongly attenuate the wave energy by absorbing some of the energy as it propagates Re ection of Waves The re ection of wave energy at a boundary between two types of materials can be demonstrated with slinkys by attaching a regular metal slinky to a plastic slinky Figure 24 The attachment can be made with small pieces of plastic electrical tape Generating P or S waves in the metal slinky will result in re ection of some of the wave energy at the boundary between the two stretched slinkys Additional information about re ection and conversion of energy S to P and P to S waves of seismic waves at boundaries is given in Figure 25 and in Bolt 1993 p 3133 i i 012 ll 1 ll 4 23 I Figure 24 Two slinkys 7 a metal slinky and a plastic slinky 7 attached together using small pieces of electrical tape The two slinkys can be used to illustrate re ection anal transmission of wave energy at a boundary between elastic materials with differing elastic properties Figure 25 Re ection and refraction transmission ofseismic waves P or S waves at an interface separating two different materials Some energy is re ected andsome is transmitted The effect can be illustrated with two slinkys 7 one metal and one plastic7 taped together Waves traveling along one slinky are partially re ected at the boundary between the two types of slinkys For seismic waves in the Earth an incidentP or S wave also results in convertedS andP energy in both the upper material re ected and the lower material transmitted Ifthe angle ofapproach ofthe wave measured by the angle of incidence i or the associated raypath is not zero the resulting transmittedP andS raypaths will be bent or refracted at the boundary A similar change in angle is also evidentfor the re ected converted waves Surface Waves The Love wave Figure 12 Table 2 is easy to demonstrate with a slinky or a double length slinky Stretch the slinky out on the oor or on a tabletop and have one person at each end xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 25 of 36 hold on to the end of the slinky Generate the Love wave motion by quickly moving one end of the slinky to the left and then to the right The horizontal shearing motion will propagate along the slinky Below the surface the Love wave motion is the same except that the amplitudes decrease with depth Table 2 Using the slinky for the Rayleigh wave Figure 11 Table 2 is much more difficult With a regular slinky suspended between two people one person can generate the motion of the Rayleigh wave by rapidly moving his or her hand in a circular or elliptical motion The motion should be up back toward the person generating the motion down and then forward away from the person coming back to the original location and forming an ellipse or circle with the motion of the hand This complex pattern will propagate along the slinky but will look very similar to an S wave compare Figures 10 and 11 Excellent illustrations of the wave motion of Love and Rayleigh waves can also be found in Bolt 1993 p 37 Rayleigh wave motion also decreases with depth below the surface Further details on the characteristics and propagation of Love and Rayleigh waves can be found in Bolt 1993 p 3741 Oscillations 0f the Whole Earth When a very large earthquake occurs long period surface wave energy penetrates deep within the Earth and propagates all around the globe At particular points around the globe the timing between this wave energy which just keeps circling the globe for many hours or even days before dying out or attenuating results in constructive and destructive interference of the wave energy The resulting oscillations at certain frequencies are called normal modes or free oscillations of the Earth and are vibrations of the whole Earth Further information about Earth normal modes the phenomenon of standing waves and diagrams illustrating the modes ofvibration ofthe whole Earth are available in Bolt 1993 p 3437 and 144145 and Shearer 1999 p 158162 Seismic Waves in the Earth Seismic body waves P and S waves travel through the interior of the Earth Because confining pressure increases with depth in the Earth the velocity of seismic waves generally increases with depth causing raypaths of body waves to be curved Figure 26 Because the interior structure of the Earth is complex and because there are four types of seismic waves including dispersive surface waves seismograms which record ground motion from seismic waves propagating outward from an earthquake or other source are often complicated and have long several minutes or more duration Figures 27 and 28 An effective computer simulation that illustrates wave propagation in the Earth is the program Seismic Waves Figure 29 by Alan Jones see reference list Using this program which shows waves propagating through the interior of the Earth in speededuprealtime one can view the spreading out of wavefronts P S and surface waves traveling at different velocities wave re ection and PtoS and StoP wave conversion The program also displays actual seismograms that contain arrivals for these wave types and phases Exploring wave propagation through the Earth with the Seismic Waves program is an excellent followup activity to the seismic wave activities presented in this teaching guide xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 26 of 36 Figure 26 Cross section through the Earth showing important layers and representative raypaths of seismic body waves DirectP and S raypaths phases including a re ection PP and pP converted phase PS and a phase that travels through both the mantle and the core PKP P raypaths are shown by heavy lines S raypaths are indicated by light lines Additional information about raypaths for seismic waves in the whole Earth and illustrations of representative raypaths are available in Bolt 1993 p 128 142 and Shearer 1999 p 49 60 Surface wave propagation Rayleigh waves and Love waves is schematically represented by the heavy wiggly line Surface waves propagate away from the epicenter primarily near the surface and the amplitudes of surface wave particle motion decrease with depth xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 27 of 36 Magnitude 65 earthquake near coast of central Chile 2929340 8 71 5471quot W l i i i i Origin time 1737590 GMT 19930903 Depth 27 km Station NNA Nana Peru 1198750 8 768422 Distance 17330 1993 km Azimuth 343 EWT east Iwes Tp NS Tnorth Amplitude Idownfp Sf Rayleigh hrminsec GMT 3 September 1998 L 17242100 17244200 1716200 17248200 I I I I I I 3 4 9 10 11 6 7 Travel time minutes Figure 27 Seismograms recorded by a 3 component seismograph at Nana Peru for an earthquake located near the coast of central Chile on September 3 I 998 The three seismograms record motion in the horizontal east west and north south and the vertical Z directions P S Rayleigh and Love waves are identified on the record The S wave arrives significantly after the P wave because S wave velocity in rocks is lower than P wave velocity Additional arrivals between the P and the S wave are P and S waves that have traveled more complicated paths such as the pP and PP phases and P to S converted phases Figure 26 from the earthquake location to the seismograph The surface waves arrive after the S waves because surface wave velocities in rocks are lower than the shear wave velocity The surface waves extend over a long time interval because surface wave propagation is dispersive the velocity of propagation is dependent on the frequency of the wave This dispersive character can easily be seen in the Rayleigh wave on the vertical Z component seismogram in that the earliest Rayleigh wave energy has a longer period lower frequency see Figure I than the later arriving waves The seismic data that are displayed here were acquired from the IRIS website wwwirisedu using the WILBER program from the IRIS Data Management Center xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 28 of 36 Earthquake Epicenter o 39 Northndge Caliiomq o mlnules 10 mlnl BS 20 minutes 30 minutes 0 11 n uuuuunn w uu aouvssm 7 7 7 7nyr7u mp7uu1u a 393 11 mg 7 0 39r 30quot YIME Ililcn onvlliqlmlo cannula I IIVDI Hm D minutes 10 minutes 20 minutes 30 minutes Figure 28 Model of the Earth39s interior and selected raypaths for seismic wave propagation from the 1994 Northridge earthquake to seismograph stations around the world Because of the existence of several types of seismic waves and the complex structure of the Earth39s interior many arrivals phases of seismic energy are present and are identi ed on the seismograms This figure is part of a poster Hennet and Braile 1998 that is available from IRIS xplorations in Earth Science Page 29 of 36 RAH Surlace 139 Omar Cure Minutes SPEED 1lll Figure 29 Partial screen views of the Seismic Waves computer program The upper image shows seismic wavefronts traveling through the Earth39s interior five minutes after the earthquake The lower image shows the wavefronts 7 minutes after the earthquake P waves are shown in red S waves are shown in blue and Surface waves are shown in yellow Three and four letter labels on the Earth39s surface show relative locations of seismograph stations that recorded seismic waves corresponding to the wavefront representations in the Seismic Waves program The Slinky The slinky was invented in 1943 and over 250 million of them have been sold The history of the slinky including its invention and the information about the company that manufactures the slinky can be found at the discovery and slinkytoys intemet addresses in the reference list Slinkys Figure 30 including the original metal slinky the plastic slinky slinky junior several quotdesignerquot slinkys made from a variety of metals and slinky toys can be found at the slinkytoys intemet address listed in the reference list Both the original metal slinky and plastic slinkys are usually available for about 2 at discount department stores such as KMart WalMart and Target A quotlongquot slinky can be ordered but can also be made by taping together two regular slinkys with small pieces of plastic electrical tape to make a doublelength slinky The original metal slinky is the most effective type of slinky for most of the wave propagation activities A double length slinky is useful for illustrating Love wave motion and the concept of standing waves on the xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 30 of 36 oor The plastic slinky does not propagate compressional or shear waves as efficiently as the metal slinky but is useful for illustrating re ection and transmission of wave energy at a boundary between two elastic materials with different properties For this demonstration tape a metal slinky and a plastic slinky together by attaching the end coils with small pieces of plastic electrical tape 393 3 ES A 34 4ng 3 355 99 D B www madquot Figure 30 Slinkys A Original metal slinky B Plastic slinky C Long slinky D Slinky junior Slinky lessons for teaching including physics and wave activities can be found at the Newtons from the Newton s Apple PBS television program and the teachingtools and eecsumich National Engineers Week activities intemet addresses The National Engineers Week slinky activities are associated with a video quotSlinky Science Shindigquot that is available from the eweek org address Slinkys are educational and fun It is useful to have many of them available for the activities described in this teachers guide and for your students to perform the activities and to experiment and discover Summary The slinky in various forms provides an excellent model to demonstrate and investigate seismic wave characteristics and propagation A summary of the slinky models and their uses in demonstrations and activities is given in Table 3 Additional information on seismic waves wave propagation earthquakes and the interior of the Earth can be found in Bolt 1993 1999 and 2004 Illustrations of seismic wave propagation through the Earth and seismograms are contained in Bolt 1993 1999 and 2004 and Hennet and Braile 1998 xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 31 of 36 Table 3 Slinky Types Models and Demonstrations Number Slinky TypesModels Demonstrations Figure Number 1 Regular metal slinky P and S waves 13 14 2 Long slinky or attach 2 regular Love wave on oor or tabletop slinkys together with plastic electrical tape 3 Slinky with cardboard Illustrate that P and S energy is 15 16 building propagating and causes the cardboard building to shake as wave arrives Differences in shaking can be seen for P and S motion 4 Two slinkys plastic and metal Re ection and transmission of energy 24 25 attached with plastic electrical at a boundary between materials of tape different types elastic properties or seismic velocities 5 Five slinkys attached to wood Show that waves propagate in all 17 18 block directions from source that travel 19 time is different to different distances and that wave vibration for P and S sources will be different in different directions from the source 6 Two slinkys attached to wood Illustrate the concept of attenuation 22 23 block one with soft foam within due to absorption of energy during the coils cardboard buildings propagation and that some materials can be attached to the slinkys to propagate waves more efficiently help see the differences in than other materials shaking Notes to the Teacher The activities described in this teachers guide are designed for both classroom demonstration and inquirybased activities for students The elastic properties of a spring and the waves in a water tank activities are appropriate for student experiments Several of the slinky activities and the human wave demonstration actively involve students in the class The slinky demos should also be performed by the students to increase their understanding of the wave propagation characteristics and concepts All of the activities provide opportunities for developing and practicing observation skills and experience with measuring and timing These demonstrations and activities are suitable for inclusion in Earth science teaching at a variety of levels At higher grade levels more complete treatment increased emphasis on necessary vocabulary de ning the xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 32 of 36 properties of elasticity describing the characteristics of motion of the different types of seismic waves etc involving quantitative measurements measuring and graphing the elasticity of a spring calculating the velocity of propagation of waves etc and connection to related seismology and other Earth science lessons and activities are desirable The depth of investigation and the length of time devoted to the seismic wave activities will depend on the grade level and characteristics of the students time available and teacher preference The teacher will also need to determine the quotdegree of constructivismquot to be employed in the teaching strategy for these demonstrations and activities For example several of the activities such as the P and Swave propagation in a slinky could be performed first as a demonstration and then by the students to develop further understanding by firsthand experience Alternatively the teacher could choose to have a brief classroom discussion about P and S waves and then challenge the students to use the slinky to discover P and Swave propagation and determine the primary characteristics of the waves property of propagation material returns to original condition after the wave has passed re ection of wave energy particle motion and the distinctive differences between P and S waves This student exploration would then be followed by a quotfinalquot demonstration to emphasize the key concepts and clarify any misunderstandings The seismic wave activities should normally be included in an earthquake unit of an Earth science curriculum that also covers plate tectonics and the causes of earthquakes Earth39s interior structure seismographs and seismograms earthquake location methods and earthquake hazards Appropriate assessment methods for the activities and science content presented here can include both written and oral responses by students and specific assessment activities The scope and depth of questioning will depend on class level time devoted to the seismic wave activities and how much related Earth science material such as studies of plate tectonics earthquake statistics and hazards Earth structure etc has been covered If student teams have completed the elasticity of a spring waves in water andor velocity of propagation experiments the teacher will have some written material from the results of the student39s experiments that can be assessed Here are some suggested activities that can be used for authentic assessment 1 Have students perform the P and S wave slinky demonstrations and describe their observations and the wave characteristics that they observe 2 Have students repeat the elasticity experiment with a spring that has a different spring constant a quotweakerquot or quotstrongerquot spring Have students predict what the graphed line will look like in comparison with their previous result then perform the experiment and graph the results Their predictions should be close to the actual results 3 Ask students to predict what would happen if a rubber band was used instead of the spring in the elasticity experiment they should describe the expected result in terms of the two main properties of elasticity 4 Provide the students with a graph showing a hypothetical seismic wave Have the students interpret the graph and identify principal wave characteristics frequency amplitude peaks etc 5 Provide the students with copies of unlabeled diagrams illustrating the four types of seismic waves lower three grids of the perspective views of P S Rayleigh and Love wave propagation in Figures 912 or from Bolt 1993 p 27 and p 37 remove labels identifying wave type Have the students identify which diagram corresponds to the four types of seismic waves and what characteristics of the wave motion allow them to identify the wave type 6 Obtain the Seismic Waves computer program and xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 33 of 36 demonstrate to the students or provide the students with the opportunity to run the program Next with the program available on a monitor start waves propagating pause or restart as necessary for one of the earthquakes and have the students watch the wavefront diagram interior of Earth it is convenient to set the display to view only the Earth cross section view use the quotOptionsquot menu and quotSelect View quot to choose the cross section view and have them answer the following questions What are the approximate shapes of the initial in the upper mantle near the source P and S wavefronts Why are they shaped that way From the P and S wavefronts estimate the relative velocity of the S wave as compared to the F wave for example how much longer does it take for the S wave to arrive at a station or to travel from the source to the coremantle boundary as compared to the F wave How long does it take for the F wave to travel directly through the Earth to the opposite side of the Earth from the source This distance the diameter of the Earth is about 12742 km From these measurements what is the approximate average velocity for P waves in the Earth in kms Explain the new wavefronts that are generated when the P or S wave hits the coremantle boundary Why is there no S wave that travels directly through the Earth to the other side Can there be S waves in the inner core the program may not be of much help here except to visualize wavefronts that propagate in the Earth39s core because no S wave phases from the inner core are displayed not all seismic phases or raypaths are illustrated by the program How could S waves be generated so that they would travel through the inner core Open the whole Earth view surface of Earth with oceans and continents is visible How are the patterns of the wavefronts that you see propagating and expanding from the source similar to the water waves in the wave tank experiment or generated by a pebble dropped into a mud puddle or a pond How are they different Below are some suggested questions for a written assessment 1 What is the source of energy for the generation of seismic waves in the slinky demonstrations in the Earth 2 How could we demonstrate that energy is carried by the waves in the slinky demonstrations 3 How can we determine the velocity of propagation of a wave 4 Explain the property of elasticity 5 Explain how the slow motions of the Earth39s plates like slowly deforming the stretched slinky in the P and S demonstrations alternative methods of wave generation can produce a rapid release of energy slip along a fault in an earthquake release of stored elastic energy in the slinky resulting in seismic waves propagating in the Earth or the slinky The activities and the science content contained in this teachers guide have significant connections to the National Science Education Standards NSES National Research Council 1996 httpwww nan J J39 39 39 39 39 as detailed in Table 4 Additional related activities can be found at httpwebicspurdueedubraile A simplified four page version of this document can be found at htt webics urdueeduNbraileedumodslink slink 4htm MS Word and pdf versions of these materials easier for printing can be found at httpweb ics nnrdne edn 39 quot J 39 sliukv linkv dnc httpweb ics nnrdne edn 39 quot J 39 01in v iinkv ndf httpweb ics nnrdne edn 39 quot J 39 sliukvslinkv4doc httpweb ics nnrdne edn quot J 39 slirrkvslinkv4pdf xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 34 of 36 Table 4 quotSeismic Waves and the Slinky A Gnidefar Teachers quot and the National Science Education Standards NSES httpww n n 1 readingroombooksnseshtmm NSES Standard How standard is addressed by Seismic Waves and the Slinky demonstrations lessons and activitiesquot Science Teaching Standards Many of the activities are inquirybased A B and provide opportunities for ongoing assessment C Professional Development Standards The guide for teachers provides opportunities and appropriate resource material for teachers to learn about an Earth science topic that is not likely to have been included in their previous educational experiences A C and includes suggestions for effective teaching strategies B Assessment Standards Authentic assessment activities and questions for assessing achievement in learning key concepts are included C Science Content Standards Unifying Concepts and Processes in Science Science as Inquiry Physical Science Standards Earth and Space Science Science in Personal and Social Perspectives Activities provide experience with observation evidence and explanation and constancy change and measurement Activities provide opportunities for practice of inquiry and of fundamental science skills Grades 58 and 912 A Activities explore properties and changes of properties in matter motion and forces transfer of energy Grades 58 B Activities explore structure and properties of matter motions and forces and interactions of energy and matter Grades 9 12 B Activities explore structure of the Earth system Grades 58 D Activities relate to energy in the Earth system Grades 912 Activities explore natural hazards Grades 58 F Activities explore natural and humaninduced hazards Grades 912 F xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 35 of 36 T ble 4 continued Science Education Program Standards Seismic wave activities are developmentally appropriate interesting and relevant and emphasize student understanding through inquiry and are connected to other school subjects B Seismic wave activities provide practice with mathematics and analysis skills C Activities provide experience with a variety of materials and resources for experimentation and direct investigation of phenomena D Science Education System Standards Because only relatively simple and inexpensive resources are necessary to perform the seismic wave demonstrations and activities they are easily accessible to all students Letters in parentheses identify speci c standards within the six areas Science Teaching Professional Development Assessment Science Content Science Education Programs and Science Education System Standards of the NSES References Bolt BA Earthquakes and Geological Discovery Scienti c American Library WH Freeman New York 229 pp 1993 Bolt BA Earthquakes 4Lh edition WH Freeman amp Company New York 364 pp 1999 Bolt BA Earthquakes 5Lh edition similar material is included in earlier editions WH Freeman amp Company New York 378 pp 2004 Earthquake NOVA series videotape 58 minutes available from 8002559424 httpwwwpbsorg 1990 Hennet C and LW Braile Exploring the Earth Using Seismology 7 Color Poster The IRIS Consortium Washington DC wwwirisedu 1998 IRIS website httpwwwirisedu Jones Alan Seismic Waves Computer program for visualizing seismic wave propagation through the Earth39s interior download from httpwww oeol 39 39 39 edn facultv iones xplorations in Earth Science Seismic Waves and the Slinky Teacher s Guide Page 36 of 36 Living with Violent Earth We Live on Somewhat Shaky Ground Assignment Discovery series videotape Discovery Channel 25 minutes httpwwwdscdiscovevcom 1989 National Research Council National Science Education Standards National Academy of Sciences Washington DC 262 pp 1996 also at httpwww nan J 139 iluui Rutherford B and S A Bachmeyer Earthquake Engineering 7 The Epicenter Project Book Pitsco Inc Pittsburg Kansas 24 pp httpwwwpitscocom 1995 Seismology 7 Resources for Teachers httpweh ics mlrdne edn 39 quot J J 39 39 39 htm a list of 39 39 J related reference materials for education Shearer P M Introduction to Seismology Cambridge University Press Cambridge UK 260pp Slinky websites httpwww discovervc 39 39 39 vtoVsSI INKY shnnlda html httgwwwslinkytoyscommainhtm htty wwwtyt orgnewtons9slink html httg wwwteachingtools comSlinkyShindigslinky html httpwww E E K Q nmirh 391 Ncoaquot 39 39 r httpwwweweekorg1999Formsdiscehtmlslinky 39 39 quot eekslink html Zubrowski BMaking Waves Beech Tree Books New York New York 96 pp 1994 Copyright 20002006 L Braile Permission granted for reproduction for noncommercial uses xplorations in Earth Science


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