Study Guide for ESCI 1012.docx

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Earth Sciences
ESCI 1012
Joshua Feinberg

Study Guide for ESCI 1012 Wildfires Factors that lead to wildfires: fuel (burning cellulose, ladder fuels, crown fire), weather (dry, windy, climate change), topography (funneling in canyons, accelerate fire, rapid spreading, rapidly upslope) Ladder fuels: low hanging brush and branches that climb up trees Causes of ignition: lightning, prescribed burns, radiation, convection, firebrands or burning embers carried in wind Fighting fires: smokejumpers, bulldozers and firebreaks, water or fire retardant, firefighters and fire lines Long-term effects of wildfires: erosion, hydrocarbon residue, water runoff in hydrophobic soils, flash floods or debris flows, air pollution Mitigation: planting vegetation, shrubs and trees, slopes being seeded, tubes of straw to provide barriers Approaches to managing fires: prescribed burns, advanced evacuation, public policy and zoning requirements, insurance Evacuation: wear wool or cotton, listen to radio, put important things in car, no legal law saying people have to evacuate, do it in advance Public Policy: zoning restrictions, insurance companies, FEMA helping people relocate Earthquakes and Plates Tectonic plates are large plates of the Earth’s crust in the lithosphere that float on the mantle. They move on average 1-12 cm per year. About 30% of the crust is oceanic and the rest is continental. Divergent/normal (Mid Ocean Ridge), Convergent /reverse(Guatemala chain volcanoes) , and Transform/strike-slip (San Andreas Fault) are the 3 plate margins Fault (crack in lithosphere where rocks slide past each other), Magnitude (number on Richter Scale), Intensity (amount of damaged caused), focus (point within earth where energy is stored and released to cause earthquake), epicenter (point directly above focus of earthquake on earth’s surface), slip (relative motion of rock on each side of the fault in respect to the other side), and rupture dimensions Seismic Waves: P waves (fastest, pas through liquid, solid, and gasses, faster than S waves), S waves (up and down motion, slower than P waves, only travel through solids), Raleigh Waves (elliptical motions “rollercoaster effect”), Love Waves (transverse motions that do the most damage) P-S-Raleigh-Love VELOCITY OF WAVES Measuring EQ’s: Richter magnitude (amount of energy released by measuring ground shaking and amplitude of waves), seismic moment (quantity used by earthquakes seismologists to measure size of earthquake based on area of fault rupture, slip and force), intensity (amount of damaged caused), logarithmic nature of scale (for every 1 increase in number of R-scale, multiply by 10) Earthquake effects: liquefaction, landslides, fires, tsunamis, aftershocks Long term prediction (10-30 years), short term (days-months): based of frequency, magnitude, spacial distribution of historical earthquakes, definitive and specific Precursors: change in # of small EQ’S, ground uplift, radiation emission, electrical resistivity, seismic wave velocity, Haicheng, China (predicted from smaller earthquakes, rise in elevation, changes in groundwater level), Parkfield, CA ( predicted quake in 1988-1993, happened in 2004) Early warning systems: Elarms (? Rapidly detects initiation of quake size, issues warning, uses P wave arrivals), detecting a large quake that sends off waves, Floods and Stream Processes Meandering (slow die of curve called point bar, fast part is thalweg, have floodplains and make oxbow lakes), braided (dry areas with coarse sediment, bedload is high, alluvial fans form), bedrock (high gradient, erodes through solid bedrock, have “potholes” from spinning rocks scouring edges) Physical features for paleo-flood analysis: high water marks, cross-sectioned areas, scour marks on rocks, tree scars, slackwater deposits Human impacts on floods: urbanization, fires, logging, overgrazing, mining, bridges Wing Dams (constrict channel width to increase river depth for barge traffic, raise water level and affect recurrence intervals), rip rap (only temporary, put at edges of rivers to keep sediment from washing away) Why dams fail: volume of water released, height of dam, valley topography, distance downstream) Mitigating flood hazards with land use: zoning land on floodplains, insurance Communities and 100 year flood estimates: use them to find out where in city will have most damage, try to prepare, warn people to get flood insurance Flood frequencies and intervals: flood frequency plots, Weibull formula ( we don’t always have 100 years of flood record to make this work, rerouted streams, bridges, dams, etc., all affect these calculations) Flood Insurance: requiring insurance on a floodplain, require it before developing land, require real estate agent to disclose flood information Factors affecting intensity and rate of runoff of flood: proximity to rainfall area, stream order, urbanization, climate Channel changing shape during flood: forms natural levees, oxbow lakes possible from flooding over land and back into river Volcanoes and Volcanic Eruptions 3 types of magma: basaltic (least explosive), andesitic, rhyolitic (most explosive) Viscosity: decreases as temperature increases, dissolved gas content increases, amount of silica decreases Melting temperature: increases with pressure for dry rocks, and melting temperature decreases with pressure for wet rocks SiO₄ tetrahedron: Silica atom surrounded by 4 oxygen, determines amount of viscosity of a magma Volcano types: Basaltic (at mid-ocean ridges, hot spots, divergent plate boundaries), Andesitic (subduction zones, convergent boundaries, wet partial melting of oceanic crust), Rhyolitic (continental crusts, subduction zones, Yellowstone Park, wet partial melting of andesitic rocks) Eruption styles: Gas (H2O+CO2+SO2, Lake Nyos with invisible CO2 clouds, Horseshoe Lake with dead trees around lake), Hawaiian (fire fountains, lava tubes, lava waterfalls, fissure eruptions), Strombolian (pyroclastic eruptions, splatter, bombs), Plinean (ash columns over 50km high, andesitic to rhyolitic, largest, eruptive columns can collapse, huge ash deposit) Kinds of specific volcanoes: Domes (Mt. St. Helens), Calderas (crater cave in, Crater Lake, Oregon), cinder cones (magma released from bottom, Flagstaff, Arizona), Maar (broad crater filled with water by magmatic interaction), shield volcanoes (Hawaii, broad volcanoes, can’t see peak) Volcanic Explosivity Index: gives numbers to volcanoes due to factors such as ejected volume, plume height, eruption type Explosivity vs. time between eruptions: larger eruptions happen less often, smaller eruptions happen more often Monitoring active volcanoes: hydrologic methods, lahar early warning systems, ground deformation, tiltmeters, lasers, GPS, seismicity, gas emissions, COSPEC, satellite observations, INSAR) Prior to eruption: ground deformation, seismicity, gas-release Lateral Blasts and Mt. St. Helens: pressur
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