GEOL 106 Lecture Notes - Lecture 10: Mercalli Intensity Scale, Seismogram, Epicenter

• School: Queen's University
• Department: Geological Sciences and Geological Engineering
• Course: GEOL 106
• Professor: David Alan Hanes

Document Summary

P-waves travel faster than s-waves: p-waves = primary waves, s-waves secondary waves. To measure earthquake focus we use travel times the time b/w the p-wave and the s-wave arrival at your seismometer. Minimum number of seismic stations to locate focus of an earthquake = 3. Note: if we only had one type of nosy wave, we couldn"t use seismometers to determine distance, and we thus wouldn"t be able to find focus/epicenter of earthquakes. But first: seismic can x-ray the inside of the earth. Centre of the earth = 6,600 km and earthquakes only happen about 700km deep into the earth (i. e the outer 10% of the earth) And 90% of the earthquakes are are at depthless than 100m. Intensity: mercalli scale (based on observed damage: subjective, varies with distance from epicentre. In hazard city you will be working on a level 9 (on the mercalli scale) Maximum amplitude of ground shaking determines the richter magnitude.