GEL 1 Lecture 17: Earthquake Faults and Damages
Calculating Richter Magnitude
●P-S time gap
○correlates with distance
●amplitude of highest wave recorded
measure of the strength of an earthquake - same value no matter where measured
Triangulating to determine location of epicenter
●for a location closer to epicenter, shorter P-S time gap but higher amplitude closer
distance
●for a location farther, longer P-S time gap but lower amplitude of ground motion
Magnitude 10x amplitude "ground motion", 30x energy released "power"
Normal fault
●moving apart
●tension forces
○divergent boundary
●lithosphere gets thinner
Thrust fault / reverse faults
●compression forces
○convergent boundaries
○squeezing stuff together
●lithosphere gets thicker
Strike-slip fault
●shearing forces
○transverse boundary
●moving side-to-side
80% faults and earthquakes on the Ring of Fire
●shallow-focus earthquakes
○85% occur in upper 20km
○rocks are most brittle at shallow depths
Red Sea mid-ocean ridge
●extension, faulting, shallow-focus earthquakes
●Saudi Arabia used to be connected to Africa
