Details Title: Earthquakes Description: earthquakes final Total Flash Cards: 68 Created: 03/16/2008 15:22:31		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Geology Flashcards
Cards in this set: Term Alaska and Aleutian Islands Definition subduction Denali strike-slip 1964: 9.2 Term Canada Definition Queen Charlotte Fault System Right-lateral strike-slip 1949: 8.1 Term Farallon Plate Definition subducted under West Coast Term Mendocino Triple Junction Definition NA-PAC-Juan de fuca moving North Term NA-PAC-Rivera triple junction Definition off Baja, CA Term Juan de Fuca Plate Definition Subducts near Oregon m9 every 1000 years volcanoes and tsunamis 4 cm/yr of convergence Term San Andreas Fault Segments Definition 1906 San Francisco 1857 Fort Tejon Creeping SEction Southern Segment Big Bend causes N-S compression Term East Bay Definition Calaveras, Hayward, Rodgers Creek Faults Term Eastern California Shear Zone Earthquakes Definition 1972 Owens Valley 1992 Landers 1999 Hector Mine Term California major faults Definition Mendocino, SAF, Hayward, Calaveras, San Jacinto, Elsinore, Garlock, E.CA shear zone (death valley) Term Deadliest EQ in India Definition Bhuj 2001 7.7 b/c poor construction and soil Term success and failure of prediction Definition 1975 Haicheng 1976 Tangshan Term Tsunami Sequence Definition 1. Interseismic elastic deformation 2. Earthquake and elastic rebound of overriding plate 3. tsunami Term Human Factors leading to tsunami devastation Definition Destroy coral reefs destroy coastal mangrove forests remove sand dunes Term Building Quality problems Definition trash in concrete mold salt water for mixing cement increase sand to cement ratio Term skyscrapers do what which leads to damage Definition resonate (damage by long-term motion) Term common building flaws Definition soft story insufficient ties holding vertical steel bars in columns poor reinforcememnt of beam to column joints Term quiescence Definition earthquakes are "due" Term Keilis Borok Definition new methods for earthquake prediction, correctly predicted earthquakes in San Simeon (December 2003) and Japan (September 2003) M6.4 or greater earthquake that his team predicted would hit Southern California between January 5, 2004 and September 5, 2004 never materialized. emerge of patterns activity ->chain order of detection chain -> activity Term to predict an earthquake, you need: Definition rate of earthquakes area of fault change in rate change in spatial distribution maximum distance between earthquakes, relative number of big to little earthquakes Term input for forecasting Definition history (instrumental, historical, geological) fault map current seismic activity geodesy physics Term questions for paleoseismologists Definition is fault active? how often do we get big earthquakes? how regularly spaced in time are quakes? does segment rupture together? Term risk= Definition hazard x vulnerability x value Term waves are reflected at interfaces, which are at: Definition shallow layers in crust mantle core/mantle boundary Term composition of earth Definition crust (30 km continental, 8 km oceanic) lithosphere (200-400 continental, 50-100 oceanic) upper mantle (down to 410) transition zone (410 to 660) lower mantle (660 to Core mantle boundary) Core mantle boundary (2800 feet deep) outer core (2800-5200) inner core (5200 to center) Term seismic tomography Definition shows where seismic waves travel faster/slower Term phase changes mean what to velocity and density? Definition 5% jumps in velocity and density Term stiffness controlled by Definition temperature composition water content crystal structure Term seismic wave velocity= Definition square root of (elastic stiffness/ density) Term slip in quake = Definition fault rate x time between quakes Term average slip rate = Definition offset/ age of feature Term stress = Definition force/area = pressure Term friction = Definition normal force x coefficient of friction (U-type symbol) Term velocity of wave = Definition wavelength x frequency wavelength/ period Term L (distance from earthquake) = Definition Ts-Tp/ (1/Cs- 1/Cp) Term ML/ Richter (local) magnitude = Definition log(A) + C A = largest amplitude C = distance Term Mo (seismic moment) = Definition UDS U rigidity of rock D amount of slip S surface area ruptured Term Mw (moment magnitude) = Definition source size 2/3(log Mo) - 6.0 Term number of earthquakes (N) w/ given magnitude (M) = Definition LogN = a-bM b=1 Term Omori's Law Definition Number of aftershocks per time decreases with time N = c/t or N= No/ (1 + kt) Term Energy in a wave = Definition wave velocity x density of soil x amplitude squared Term Snell's Law Definition Sin Θ1/ V1 = Sin Θ2/ v2 for refracted wave Sin Θ1 = Sin Θ2 and v1 = v2 for reflected wave Term Wegener Definition Continental Drift Term Argand Definition Nappes Term Holmes Definition Convection Term Some Subduction Zones Definition WASaSuJ Washington-Oregon Alutian South America Peru-Chile Sumatra-Java Term Exceptions to earthquakes on plate boundaries Definition Blurring of plate boundary: collision (India- Asia) Failed Rift (New Madrid) Ice loading/ Unloading (hudson bay) hotspots (hawaii) Term Harry Fielding Reid Definition Elastic Rebound Theory Term 2 ways to change friction Definition change normal force change coefficient of friction (lubrication--cracks in rocks) Term Complexities along strike-slip fault Definition pull apart (extention) -> enclosed depression (sac pond: Dead Sea) Compressive jog -> ridge (push up) Term Thrust Fault Characteristics Definition Topographically irregular low dip angle perched terraces deeply incised canyons Term Normal Fault Characteristics Definition Perched Terraces Alluvian Fans Slickenlines (grooves) Term one point on fault plane slips at ___ during quake Definition 1 m/s Term What affects velocity Definition strength of material (high pressure = stronger, high temperature = weaker, weaker = slower) Density (higher density = slower velocity) BUT velocity increases moving downward??????? Type of Wave Term Needed for a seismogram Definition 1. 1 part attached to ground 2. intertial mass isolated from ground (to compare motions) 3. spring to return mass to original position 4. damping mechanism (so it doesn't bounce forever) 5. pivot (hinge) so mass moves in 1 direction 6. sensitive at seismic frequencies Term When you increase magnitude by 1, what happens to amplitude, length of fault, duration of slip, and energy? Definition 10x greater amplitude 3.3x greater lenght of fault, duration of slip 33x greater and energy Term what scales with magnitude? Definition moment, energy, duration, fault length, slip Term Fault Rupture Lengths vs. magnitude Definition 8 = 250-500km 7 = 50-70 6 = 10 5 = 1.5-2 4 = 200-400 m 3 = 30-80 2 = 5-20 Term Reasons for delay of aftershocks Definition static fatigue visco-elastic relaxation diffusion process (pore fluids) Term swarms Definition sequence of earthquakes with no clear main/aftershock relation most common in volcanic areas one of best ways to predict eruptions Term For elastic materials, _____ is proportional to ______ Definition stress is proportional to strain Term Effects/ Lessons From: 1812 EQ Fort Tejon, SF, Long Beach, Kern, Sylmar, Northridge Definition 1812: damaged missions, trees are good source of info Fort Tejon, SF: haven't ruptured since, new building codes after SF, Long beach: improvements in zoning, Kern: thrust fault in CA, sylmar: structures damaged by strength and duration of shaking (dams subject to liquefaction), northridge: blind fault Term Threshold Probability Definition minimum chance that something will happen. Ex: there is at least 30% chance that an event will happen Too high: miss some EQ Too low: generate false alarms Term Kobe Earthquake Definition 1995: 6.9 Costliest Earthquake Term Frame Action Definition connected steel frames resist lateral forces by flexing Term 1906 San Francisco Definition 7.9 largest in CA, most damaging hasn't ruptured since IX on mercalli scale region of destructive intensity extended over 600 km Term CA Earthquake lessons Definition large EQ have large rupture area EQ occur in unexpected areas exposed fault not necessarily indicator of size EQ interact and sometimes progress Term Death Valley Definition formed by conjugate normal faults