Earthquakes
Focus (hypocenter) first location of slip on fault
Epicenter-location on the earths suface above the focus
seismic waves
Body Waves
P waves-compressional primary
S waves-shear secondary
Surface waves slowest
Difference in arrival time of seismic waves determines distance to EQ
seismograph-measures earthquake waves and ground motion
use 3 stations to pinpoint location of EQ
2 ways to measure earthquakes
MAGNITUDE-energy released-either using the Richter scale (old) or the Moment
Magnitude Sale (newer-based on fault area and amount of slip)
INTENSITY-damage done during the earthquake-Mercalli Scale
Effects of earthquakes-ground cracks, landslides, liquifaction, tsunami, fire, flood
Tusnami-seismic sea waves-know where they form (at large undersea earthquakes), and
what type of damage they do-large wall of water, may have many waves that are widely
spaced (up to .5 hours) apart.
How do we distinguish ancient tsunami? sand layers, dropped land (dead trees)