Geology 105 Final Exam Study Guide
Geology 105 Final Exam Study Guide Geol 105-010
Popular in Geological Hazards and Their Human Impact
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This 9 page Study Guide was uploaded by Tonisha Hurd on Thursday May 19, 2016. The Study Guide belongs to Geol 105-010 at University of Delaware taught by Kohut,Edward John in Spring 2016. Since its upload, it has received 79 views. For similar materials see Geological Hazards and Their Human Impact in Geology at University of Delaware.
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Date Created: 05/19/16
Geology 105 Final Exam Study Guide What factors drive weather? Solar Energy Unequal heating of earth’s surface Water Cycle affects weather because of energy and mass movement in atmosphere Air masses, highs and lows, jet stream and fronts. Air Masses and Fronts Regions of similar temperature and humidity (amount of water vapor) Boundaries between air masses are fonts Warm Front Advancing warm air Pushes over colder air Cold Front Advancing cold air Pushes under warming air Highs and Lows High pressure: Air converges aloft, Diverges at surface Winds blow out clockwise in northern hemisphere Fair weather, calm winds gather near center Low Pressure: Air converges near surphase Diverges aloft Winds blow counterclockwise in northern hemisphere Strong winds and precipitation near center Storms Jet Streams Narrow air currents Exist between troposphere and stratosphere Form along boundaries of global cells May form meanders or waves Steer fronts and storms What is a cyclone, differences between tropical and extratropical. Cyclone a low pressure area with closed circulation Tropical storms, hurricanes, typhoons and cyclones Tropical vs Extratropical Tropical (TC) Extratropical (ETC) need warm water to form Can form over land warm core coldcore highest winds at center highest winds over a large area * fronts can steer TCs apart form along fronts storm surge storm surge if over ocean heavy rains rain and/or snow *usually less intense SaffirSimpson scale, what it measures and what it doesn’t. MEASURES HURRICANES STRENGTH 5 Categories of hurricane strength 1 No real damage to building structures. Winds 74 95 MPH 2 Damage to roofing material, door and window. 96 110 MPH 3 Structural damage to small residences. 111 129 MPH 4 Extensive wall failures with roof structure failure. 130 156 MPH 5 Complete infrastructure failure. 157> MPH DOES NOT MEASURE Surge and rainfall not used because they are dependant on factors beside windspeed Storm surge o Rise in sea level due to low pressure and winds o Combo of surge and tide is the storm tide o Highest surge is in the upper right quadrant of the storm o Surge of 2013’s Typhoon Haiyan in Philippines was 56 meters (16.5 20 feet) o Surge from Katrina exceeded 8 meters (25 feet) in places o Surge from 1970’s Bhola cyclone killed ~500,000 in Bangladesh o Globally, storm surge causes 90% of tropical cyclone deaths Relationships between storms and floods, landslides, coastal hazards. COASTAL HAZARDS Waves Result from wind on water’s surface The higher the wave, the more powerful Wave refraction: if wave approaches shore at angle other than 90 degrees will bend or refract This end moves in shallow water much slower than the rest of the wave Longshore Drift Some waves approach coastline parallel causing Longshore current Current along the shore Longshore drift moves sediments along cost Tides Daily change in sea level due to gravitational pull of sun and moon. Highest parts of the tidal cycle during the Spring Tides Full Moon and New Moon. Neap Tides quarter phases of the moon. Happens every month Height and number of cycles per day vary around the globe. o Diurnal: One High Tide and One low tide o Semi diurnal: happening every 12 hours o Mixed semidiurnal: Throughout the day The larger tidal range, the stronger the tidal currents Tidal currents may dominate in an area and be the primary control on erosion and deposition. Timing of tidal cycle critical for determining the storm tide. Rip Currents Where wave energy flows back out to sea Incorrectly called “rip tides” Have nothing to do with the tides Beaches Beaches o Sloping Surface made of loose sediment Sediment could be many things; sand, shells, coral, gravel sized material, rocks, boulders, etc. Most often, the most popular beaches are made of quartz sand o Easily moved by wind and tides o May have seasonal changes Parts of beaches Onshore: Sea cliff: along the seashore there is a line of sand dunes or vegetation Berm: The landward slope Formed by deposition of sediments as waves rush up. Beach Face: Slope seaward begins when beach slopes downward toward ocean Swash zone: where waves rush up and down on the beach face Offshore: Surf zone: Nearshore environment where turbulent water moves toward shore Breaker zone: Area where incoming waves become unstable, peak and break Sandbars (Longshore bar): forms beneath each line of breakers in breaker zone Longshore trough: formed by wave and current action Seasonal Beaches Seasonal Beach Profiles o In the winter, storm waves increase erosion. o Sand washed off beach is stored in bar offshore. Some may be transferred down the coast. o In the summer, smaller waves and tides redeposit sand on the beach. Barrier beaches o Beaches separated from mainland Absorb energy, protect land behind beach o Protect land behind the beach o Change over time Beaches spits o Longshore drift can produce projection of sand into bays and inlets Spit a claw shaped, sandy to gravelly coastal landform at the end of a peninsula. Formed by accretion of beach ridges in direction of longshore drift Headlands and terraces o Steep coastlines (west coast and maine) May be rising o Waves and tides acting on exposed bedrock o Wave cut terraces Uplift keeps bringing bedrock to surface Sediment deposition unable to keep up with erosion Wave refraction focuses energy on headlands Cause sea cliffs to erode landward Energy spread out in bays between headlands Zones of deposition Coastal Mitigation Coastal Hazards Mitigation o Beach Hardening Sea Walls or Rip Rap o Breakwaters/ groins o Beach Nourishment o Retreat Rip Rap/ Beach Hardening o Can actually accelerate erosion in front of sea wall or rip rap Wave energy is not absorbed by sand, rather it is reflected back onto the beach, which causes more erosion. Breakwater: structure built in front of shore, parallel to it. o Groins: a series of structures projecting perpendicular to the shore line Purpose is to arrest/stop the longshore drift o Jetties: structures on one or both sides of an inlet, meant to keep the inlet open. Beach Nourishment o Much like Dan, this is called a “SOFT solution” o Pump sand onto beach from offshore bars o Or bring in sand on trucks In 1982, Ocean City NJ spent 5 million on beach nourishment. New Material eroded away within 2 ½ months. Beach had been nourished 22 times between 1952 and 1995 Aggravation The Problem o Shorelines respond dynamically to coastal waves, tides and currents Erosion and deposition, change over time. o We move to these dynamic places and want them to remain static. We use static strategies to “protect the shore” when in reality we only seek to protect our structures and development. o Result: the “problem” is often aggravated, hazards are shifted elsewhere and/ or worsened. Climate Characteristic weather at a particular place or region during many seasons, years or decades. The ocean conveyor Exchange of warm surface water and cold deep water Multiyear Oscillations Variability within the global climate. Can shift weather patterns for a year, several years or decades. El nino Southern Oscillation: Change in air pressure and sea surface temperatures in the Pacific Can cause dramatic changes in weather patterns Arctic Oscillation: o Change in pressure over the arctic, which affects the jet stream patterns Average Temperatures Daily, monthly, seasonal and yearly temperatures can be reduced to a single average temperatures can be reduced to a single average. o Can be local, regional or global. If Climate is stable, there will be very little change in the average over time. A small shift (0.251 degree C) may then reflect very large local or regional changes. Climate determinates Climate is a metastable system o May have shortterm variability and regular fluctuations, but self corrects But, will switch to a new metastable state if forced Good land thermometer records date back to the mid 1800s o At least for the Northern hemisphere Ocean air and water temps back to early 20th century Satellite measurements since 1900s To go back further, we use “proxies” o Tree Rings Tree growth affected by temperature and precipitation, looking at the rings of the trees gives us an idea of its growth, therefore an idea of the climate. o Fossils Location of past life forms reflect past climate conditions o Ice Cores The Greenland and Antarctic Ice Sheets and mountain glaciers add ice each year. Same deal as the tree rings; amount of snowfall and ice added gives us an idea of what the climate was like millions of years ago. Dust and pollen may be trapped within layers. Bubbles form in the ice, trap the air from millions of years ago. Use the bubbles to measure temperature, air content (CO2, oxygen levels etc.) Solar Forcing Solar output changes over time o Regular 11 year cycles o Much longer, irregular cycles as well. Active sun has more sunspots and releases more energy Orbital Forcing Changes in shape of orbit and tilt of Earth change amount of solar energy received. Follow Known cycles Milankovitch cycles variations in solar radiation reaching Earth due to variations in Earth’s orbit Cycles of glaciation during the past 2 million years driven by Milankovitch cycles Tectonic Forcing Location of landmasses affect: o Ocean circulation o Continental Ice sheets Configuration of continents determined by plate tectonics Cause very gradual changes over tens of millions of years Albedo Measure of reflection o High albedo= high reflection High albedo reflects more solar radiations o Snow and ice o Sulfur dioxide (SO2) and ash from volcanoes o Sulfur dioxide in the stratosphere will block and reflect some incoming solar radiation. o Can cause short term cooling Greenhouse Effect Gases in the atmosphere absorb infrared radiation (heat) o Water o Carbon Dioxiide o Methane Sources of Greenhouse Gases Water o Amount in atmosphere varies with climate Methane o Biological activity, melting permafrost, deep sea methane hydrates Carbon Dioxide o Volcanic activity, wildfires, reduced vegetation, buring of hydrocarbons from crust. Climate Change (Past, Present, and Future) Current Warming If you were born in or after April 1985 (27 or younger), you have never lived through a month that was colder than average. Temperature has been above average since then. Warming since 1850 Extensive studies have ruled out solar forcing, orbital forcing What HAS changed is a dramatic increase of CO2 due to ever increasing burning of fossil fuels since 1850. Increasing CO2 due to burning of fossil fuels o Anthropogenic Forcing CO2 emissions continue to rise worldwide Effects of Warming o Sea Level Rise Volume of oceans increases with water temperatures Melt of ice sheets on land will also contribute Rising at ~3mm/yr, rate increasing since 1990s Rising faster than models have forecast Climate change Remove CO(2) o Carbon Sequestration Reduce CO(2) emissions o Only 2 industrial countries recently reduced emissions: US and Germany. Adapt o Will have to, to some degree but impossible to adapt everywhere to the worst case situations. Ignore or Deny the problem WILDFIRES Conditions Natural o Lightening Human o Accidental o Loss of control of intentional burns o Arson Fire Science Fire is a Chemical reaction o Combustion rapid oxidation with a large release of energy Flames ionized gas or plasma Byproducts Carbon dioxide, other (toxic) gases, unburned particles (soot, ash, charcoal) Fire Types Depend on fuel source o Ground, surface and crown Many fires… Ground Fires Burn in dry organic material in soil Crown Fires Surface fires may climb ladder fuel (small trees and underbrush) to reach crowns of large trees Many woodland fires only burn in underbrush Full grown trees often survive But if tops of trees are involved o Fires spreads faster o Burns hotter o Trees destroyed Firestorm Fire grows large enough to create powerful inflowing winds o Intensity and….can suck people in Fire Triangle Ingredients needed for fire Fuel Oxygen Heat Fire Fighting Allow natural burns in regions where fires are part of ecosystem o Policy today is to let the small ones burn and just keep an eye on them When fires are large or threaten settled areas, attempts are made to control them Removing one or more sides or the tetrahedron Examples: Oakland Fire, California October 1991 $2,687 Billion Cedar Fire, California October 2003 $1.24 Billion Witch fire, California October 2007 $1,142 Billion Old Fire, California October 2003 $1,141 Billion Los Angeles County Fire November 1993 $559 Million FINAL THOUGHTS 5.16 Fundamental Concepts for Understanding Natural Processes as Hazards Hazards can be evaluated scientifically So can the risk Population factors and the response of a society an important part of determining whether there is a disaster or a catastrophe Hazardous events that previously produced disasters are now producing catastrophes o Increased Population o Influence of climate change Consequences of hazards can be minimized Approach to Geological Hazards Identify location of hazard Determine recurrence interval and probability of event Estimate cost of the event and determine risk Make a “forecast” or “prediction” Observe/monitor any precursor activity and provide warning Mitigate. Educate. Mitigate. Educate. Suck a dick. Mitigate. Educate…
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