CEE 437: Earthquakes and Seismology

• Mechanisms and Locations • Seismic Waves • Magnitude and Distance

• Seismic Risk

• Nov. 3, 2002 Denali Fault, Alaska Quake

Earthquake Mechanisms

• Iso-static Rebound (post-glacial) o Fennoscandia (m=8.4?)

• Volcanic o Mt. St. Helens, Hawaii

• Induced Seismicity o by increased fluid pressure in well-field or reservoir

• Plate Tectonics o Subduction Zones and Plate Collisions o Transform Boundaries o Mid-ocean Ridges and Continental Rifts

Induced seismicity at Rangely, Colorado, 1967

Induced seismicity in India, 1967

Intermediate Depth Teleseismic Earthquake

Gutenburg-Richter law

log N = - b m + log a

where N = number or number/yr m = magnitude b = b value, 0.8 < b < 1.2 a = constant

Energy release of earthquake

log E = 1.5 m +11.4 E ~ 30*m

Modified Mercali Intensity

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