Earth Sciences 2240F/G Lecture 4: Earth science 4

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 2240F/G
• Professor: Jennifer Mac Rae

Document Summary

4. 2 magnitude: before charles richter created an objective magnitude scale, the strength of earthquakes was measure subjectively: the amount of observed damage ect. Modified mercalli intensity scale: believed that intensity could be determined by properly interpreting the strength of energy waves reaching seismographs. 4. 3 moment magnitude scale: to remedy the non-scalar behavior of large earthquakes the. @ the surface where water from liquefied layers squirts out the ground. Divergent plate boundaries: earthquakes at these locations, therefore, should be numerous, close to surface, and low magnitude. To be effective a prediction must define: location of the event: time expected (within hours rather than weeks or years, magnitude that is probable, only ever been one successful save. Foreshocks: microfractures weaker rock sections produce small releases of energy swarms of tiny earthquakes as the fractures form. Seismic gap: over a long time no motion on a fault but motion has occurred to either side.