GEOLOGY 1 Lecture Notes - Lecture 8: San Andreas Fault, Seismometer, Elastic Energy
Document Summary
The first step in a risk analysis of a natural hazard: understand the hazard. The rigid part of the earth can store elastic energy- when it breaks the elastic energy is released. Earthquakes happen when either a fault forms or there is an episode of movement on a pre-existing fault. Fault: a break/crack in rocks along which there has been appreciable displacement. For a big earthquake fault motion need to be only a meter or so. Strike-slip faults- horizontal motion, look for offset streams. Reverse dip-slip faults- sub-vertical or vertical movement, results in a fault scrap, energy pushes land together. Large earthquakes can be associated with any of the 3 fault types but the biggest are associated with reverse dip slip faults. Rivers are often found to occupy faults/ fault zones (because the broken up rocks can be more easily washed away) We often build major dams on such rivers because the rivers make canyons.
