ERTH 2415 Lecture Notes - Lecture 1: Cascadia Subduction Zone, East African Rift, North American Plate
10 Oct 2016
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Document Summary
Earthquakes do not occur at random locations. Relation between tectonic environment, deformation forces and earthquake characteristics. Divergent zone: dominant deformation force: tension, stress is released in frequent, strong and shallow earthquakes. Centering: lithosphere centers over a hot region at depth. Doming: increase in heat causes the earth"s lithosphere to bulge up into a dome. Spreading: new ocean floor is formed in pulled apart area. Rifting stage: rifting started 25 million years ago, 3 zones of tension meet at the afar triple junction (red sea, gulf of aden, east african rift system) Some rifts do not fully develop into new oceans: stop at stage 3 (never fully open as oceans, zones of weakness in the crust, but they are not active anymore, create zones of weakness in the crust. Convergent zone: region where 2 tectonic plate collide, dominant deformation force: compression. Looking more closely: plates under different stresses at different depths.
