Geography 2152F/G Lecture 10: 2152-Final
10 Dec 2017
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We want to multiply the tens therefor m3-m5 is 10x10x10. Except for very large earthquakes, the magnitude on the moment magnitude scale is similar to the richter scale. The strongest earthquake to ever occur is m9. 5 in chile in 1960. There are only a few m9+ earthquakes each century. The modified mercalli intensity scale is a qualitative scale based on damage to structures and the affect on people. Earthquakes are most common at or near plate boundaries. Motion at plate boundaries is not usually smooth or constant. Friction along plate boundaries exerts a force (stress) on the rocks, exerting strain or deformation. When the stress exceeds the strength of the rocks, there is a sudden movement along a fault. The movement (or rupture) starts at the focus and propagates in all directions, called seismic waves. Identifying faults is necessary to evaluate the risk of an earthquake in a given area.
