University:
Amherst College
Course:
GEOL 111 | Planet Earth: Introduction to Geology
Academic year:

2022
Views:

350

Pages:

25
Author:

Nathaly Davidson

1906 San Francisco earthquake 664 deaths in the Bay area 28,188 buildings destroyed Stanford University $400 million (1906 dollars) lost known until the 1960’s as the1906 fire 1964 Anchorage, AK earthquake largest earthquake and tsunami until 2004 Magnitude 9.0 earthquake 2:46 PM March 11, 2011 370 km NE of Tokyo, focal depth ~25 km ~ 80 km E of Honshu All earthquakes caused by slippage along a fault Continuous movement Elastic energy builds up gradually Eventually enough strain energy is stored elastic rebound Finally… the fault slips Earthquakes occur along plate boundaries Earthquake FOCUS along plate boundary Generates SEISMIC WAVES that travel through Earth Seismic waves recorded by seismograph 1989 SF earthquake recorded in Finland 10 min particles move in direction of wave propagation Body wave: can travel THROUGH Earth particles move perpendicular to direction of wave propagation Body wave: can travel THROUGH Earth particles move in retrograde ellipses Surface wave: must travel AROUND Earth particles move along surface perpendicular to direction of wave propagation Surface wave: must travel AROUND Earth Seismogram: seismic waves of 1989 World Series earthquake recorded in Finland P-waves always arrive first followed by s-waves surface waves always come later 3-d seismogram shows direction of ground motion K: compressibility µ: shear modulus ρ: density Seismic velocity related to density and elastic properties: compressibility and shear modulus P waves are always faster than S waves velocity decrease: downward refraction faster slower velocity decrease: downward refraction faster mantle core slower velocity decrease: downward refraction faster mantle core slower

1906 San Francisco Earthquake

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