ERTH 2415 Lecture Notes - Lecture 4: East African Rift, Plate Tectonics, Triple Junction
11 Jul 2017
School
Department
Course
Professor
Document Summary
To understand the relation between tectonic environments and earthquake characteristics. Magnitude- the amount of energy released during an earthquake. No earthquake below 700 km: material in plastic mesosphere not rigid enough to break abruptly. Divergent zone: dominant deformation force- tension, stress is released in frequent, strong and shallow earthquakes. Formation of new oceanic lithosphere: centering- lithosphere centers over a hot region at depth, doming- increase in heat causes the earth"s lithosphere to bulge up into a dome, rifting- area is pulled-apart by tension. The central area sags: spreading- new oceanic lithosphere is formed in pulled-apart area. Example of a young divergent zone east african rift system. Failed rifts: some divergent zones do not become fully-developed spreading centres with oceanic floors, stop at stage 3 rifting", create zones of weakness in the crust. Convergent zone: region where two tectonic plates collide, dominant deformation force- compression, shallow, intermediate and deep earthquakes. Immense amount of energy is stored then suddenly released.
