Popular in Geological Hazards and Their Human Impact
Popular in Geology
This 12 page Study Guide was uploaded by Ashley Thompson on Thursday October 29, 2015. The Study Guide belongs to GEOL105010 at University of Delaware taught by McGeary,Susan in Spring 2015. Since its upload, it has received 27 views. For similar materials see Geological Hazards and Their Human Impact in Geology at University of Delaware.
Reviews for Exam 2
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/29/15
Volcanoes 102915 750 PM Black Board 0 Earth s Internal Energy 0 Earthquakes tsunami volcanoes Volcanic Eruptions 0 Cannot be prevented 0 Can be predicted Precursors EQs magma motion Ground surface deformation Gas escaping 0 Not all volcanic eruptions are explosions Two types of magma n Basaltic magma VERY DARK ROCK Produces volcanic rock called basalt Almost never explosive Produces shield volcanoes not explosive o EX Hawaii Iceland MidOcean Ridge n AndesiticRhyolitic magme DIF COLORS LIGHT Produces andesite rhyolite 0 Sometimes explosive eruptions sometimes not 0 Produces Strato volcanoes large calderas domes o EX Fugi Powerpoint 0 Definitions 0 Magma molten liquid melted rock Not just liquid must have some liquid for it to be magma could have crystals or gas When magma is at the surface a Either flows out as lava flow a Explodes out as pyroclastic eruption Producing cloud pyroclastic flow 0 Lava magma that flows on Earth s surface 0 Pyroclasts exploded magma ash cinders pumice bombs What is an Active Volcano 0 South fissure flank eruptionetna 34km high 0 melt rock drop pressure increase temp something else Volcanoes 102915 750 PM Magma Molten rock liquid 0 Solid crystals 0 Dissolved gas H20 C02 Chemistry of Magma Main two elements make up silica content 0 Silicon 0 Oxygen 0 Can have others 0 Magnesium F Iron Calcium Sodium K Aluminum SiOZ How much Silica Content 0 Felsic 70 9 high Rhyolite high viscosity sticky 0 Intermediate 60 9high9andesite9high viscosity sticky o Mafic 50 low Basalt low viscosity runny o Ultramafic lt45 low9komatite do not need to know 0 Property 0 Viscosity 0 Resistance to flow 0 Two Necessary Ingredients for Explosive Magma volcano o NEED BOTH ONE IS NOT SUFFICIENT High viscosity Dissolved gas OOOOOO POWERPOINT 0 Table 61 in textbook Volcanoes 102915 750 PM Exam 80missed80 Volcanic Hazards Lava Flows effusive generally not deadly Pyroclastic Flows explosive most deadly kills the most people 0 Ash Fall Lahars volcanic mudflows Deadly Gases Lahars 0 Almost 25000 people in unsuspecting town were drowned or buried by the thick mud Volcanoes 102915 750 PM 101415 Pinatubo Convergent Plate Boundary o Subduction Magma 2 Dark Volcanic Rocks Basalt Vesicular Basalt 2 Light Volcanic Rocks Rhyolite grey with black specks Andesite tan 119 Volcano Types Shield Volcanoes Largest volcanoes in the world 0 Common in Hawaiian Islands Iceland and Indian Ocean 0 Associated with Basaltic Magma 0 Low viscosity low volatile content 0 Gently flowing lava with nonexplosive eruptions Built almost entirely of lava flows 0 Thin lava flows build up volcano with gentle slops o Resembles a warrior s shield Can form lava tubes underground Composite Strato Volcanoes Magma is more viscous with a higher volatile content 0 A variety of lavas from basaltic to a combination of andesitic and rhyolitic o Mixture of explosive activity and lava flows 0 Produce a combination of lava flows flat magma and pyroclastic deposits gassy magme 0 Have a cone shape also called stratovolcanoes Explostions are more violent and dangeroud EX Mount St Helens Mount Rainer Mount Fuji Cinder Cone Volcanoes Small volcanoes build from an accumulation of cinders a type of pyroclast 0 Small pieces of black or red lava o Formed when laval meets groundwater 0 Common on larger volcanoes normal faults or along cracks and ssures 0 Also called scoria cones EX Paricutin Mexico Lava Domes Made from highly viscous magma andesite or rhyolite Can exhibit highlt explosive eruptions but only if magma is gassy 0 Small domes often form within the crater after an eruption EX Lassen Peak and Mono Craters Calderas Vents 0 Any opening for lava and debris 0 May be circular or thin fissures 0 Can produce flood basalts Craters o Depressions formed by explosion or collapse of volcano o A few kilometers a mile in diameter 0 Calderas 0 Very large crater formed from violent collapse of a cone 0 May be 20 or more kilometers 12 or more miles in diameter and contain vents and hot springs Caldera Eruptions Very rare extremely violent eruptions rhyolite 0 Produce huge amounts of ash and forms calderas 0 Sometimes referred to as supervolcanos by media 0 Most recent North American caldera eruptions 640mya at Yellowstone National Park and 700 mya at Long Valley California Streams and Flood Processes I 102915 750 PM What happens to most of the water evaporated from the ocean o It returns to the ocean as rain or snow Hydrologic Cycle Pools on blue fluxes in black 0 Note that all the fluxes balance suggesting that all the pools remain the same through time 0 But the volume of ice is decreasing now due to global warming 0 What happens if there is an inbalance in the water budget Example what if more water evaporates from the ocean than returns to the ocean in rainfall or river flow 0 Sea level drops Of course that water has to go somewhere 0 Mostly stored on land as glacial ice 0 A small amount could be stored on land as groundwater and lakes 0 A very very small amount could be stored in the atmosphere as water vapor higher humidity The Hydrologic water Cycle 0 Stream flow is part of the hydrologic cycle 0 Major parts of the hydrologic cycle 0 Evaporation evapotranspiration o Precipitation 0 Interception o Infiltration 0 Surface flow A small watershed drainage basin in a mountainous area 0 Watershed boundary not the boundary is closed 0 Watershed outlet all water leaving the watershed as surface water passed through this point Watersheds and Drainage Divides Watersheds exist at multiple scales 0 Large watersheds contain may smaller watersheds 0 Continental divides separate drainages that flow to different water bodies eg to Gulf of Mexico vs Atlantic Ocean Volcanoes 102915 750 PM Mt Saint Helens 0 Sequence 0 1 Formation of the bulge o 2 Magnitude 5 EQ o 3 Landslide of bulge o 4 Excavated top of magma body pressure release 0 5 Pyroclastic explosion Where volcanoes occur divergent plate boundaries 0 midocean ridges basalt Iceland 0 Continental rifts9basalt East Africa 0 Convergent plate boundaries 0 Subduction zones9andesite rhyolite Pinatubo Fugi Hotspot Volcanoes Oceanic Basalt Hawaii 0 Continent Rhyolitebasalt Yellowstone Hotspot planetary something Streams and Flood Process II 102915 750 PM On Black Board 0 Discharge a measure of streamflow 0 Volume of water passing through a point on a river per second MeterA3sec or feet3sec 0 Stage height of water in river 0 Flood stage Hydrograph a plot horizontal axis is time vertical axis is discharge in quantity Q 0 Area of channelwidthXdepth ftxft ftAZ Water velocity fts o QAxVelftA2ftsft 3s Powerpoint 0 Materials Transported by Rivers 0 Rivers transport materials along with water 0 Total load consists of Bed load materials that roll slide bounce along bottom Suspended load silt and clay particles that are carried in the water Dissolved load materials carried as chemical solution If one of these decreases Infiltration decrease then runoff increases likelihood of flooding increases 0 Interception decrease then runoff increases likelihood of flooding 0 Surface flow aka runoff overland flow Flooding need more water than the channel can hold 0 Natural process usually get small floods twice every 3 years or so 0 Get more water quickly coming into river channel Cause infiltration decrease 0 Natural 0 Ground already fully saturated 0 Frozen ground 0 Clay soil 0 Hard rock or soil 0 Human o Urbanization building parking lots pavement This creates a quick discharge flash flood Low Flow 95 of the time Mean annual flow 30 of the time Bankfull flow 2 times in 3 years on average Moderate flood every 10 years on average Heavy rainfall on nearsurface bedrock Guadalupe River Texas 0 Rapid overland flow runoff leads to flash flooding multiple times Downstream flood 0 Spring thaw on a northflowing river Red River North Dakota 0 Unusually heavy snowpack provided an unusually large source of meltwater in the spring in 1997 0 Flood water trapped in the US to the south because the northern parts of the river are iced over Impacts RiskCost of single event x Probability So cost RI Asteroids Comets Left over debris from solar system formation Mostly Rockmetal Asteroid Belt Circular orbits High velocity Left over debris from solar system formation Mostly ices Orpt cloud Ellipse orbit Higher velocity 102915 750 PM 102915 750 PM
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'