GEO 1111 Lecture Notes - Lecture 8: Basalt, Continental Crust, Outer Core

• School: University of Ottawa
• Department: Geology
• Course: GEO 1111
• Professor: Donald Cummings

Document Summary

Seismic waves generated by earthquakes could be measured by using sensitive pendulums (seismometers) Logarithmic scale : each whole number represents a 10 fold increase in ground motion (corresponds to 32 fold increase in released energy) Largest : 160 valdivia in chile, 9. 5 on richter scale, 1019 j energy released ( 2 billion tons tnt) Spread in arrival time b/w p and s waves increases with distance from epicenter. Used to ascertain distance b/w seismometer and epicenter. P-waves travel about twice as fast as s-waves. Two things use to determine the magnitude of the earthquake. Amplitude of largest seismic wave (max amplitude) recorded & Distance of the seismometer to the epicenter (determined from p-s interval) Distances at each station determined from p-s time interval. Earth"s density > rocks from crust"s density must be denser material in the earth"s interior. Layered model of the earth - proposed by emil wiechert (1896) (low density mantle, high density core)