Week 8
Earthquakes and the Earth's Interior
Week 8
Earthquakes and the Earth's Interior
Introduction
Earthquakes represent one of the most frightening and spectacular geologic phenomenon with which we have contact. Earthquakes release energy equal to more than 100 atomic bind of the type dropped at Hiroshima in 1945.
Earthquakes occur as a result of the buildup of stress in the crust until failure occurs, the rock fractures, and energy is released as a result of the failure.
Original state
Stress build-up and deformation
Failure and release of energy
Earthquakes release energy in the form of waves that are recorded by instruments called seismographs.
Earthquakes release two major types of waves, P waves and S waves.
P-Waves are waves in which the particle movement is in the same direction as the movement of the waves.
S Waves are waves in which the particle movement is perpendicular tot he movement direction of the waves.
Seismographs and waves. P waves travel faster than S waves as can be shown below.
Seismic wave arrivals can be used to determine the location of an earthquake, if we look at the data from three seismographs for the same earthquake.
Try your luck at locating an earthquake based on three seismic records.
Stress states and faults
Compression
Extension/tension
Shear
Tsunamis
Earthquake damage is mostly due to the movement caused by the seismic waves and related shaking effects. Another potentially catastrophic occurrence is the tsunami. Click the link below to learn more.