EARTH 108 Lecture Notes - Lecture 2: Plate Tectonics
14 Jun 2016
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Lecture outline: where earthquakes occur, plate tectonics in brief, why earthquakes occur, types of earthquakes, are there unexpected earthquakes, earthquakes in michigan. From 7-14th january 2013, there were 279 earthquakes worldwide. 28 of these earthquakes happened in the u. s. At low stress (pressure and force) rock is elastic. At high stress (pressure and force) rock flows like syrup. Very deep in the earth, rock is very hot and under very large stresses. It is solid (at most ~5% melt in places), but it flows like syrup over millions of years. Near the surface rock is colder and harder, and does not flow. The outer layers of earth break up into tectonic plates. The tectonic plates are pushed around on the globe due to flow of rock below. Earthquakes occur along the boundaries where the plates move past each other. Plate boundaries composed of one, or more faults.
