17 terms

Ch. 10 Earthquakes

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Where do the deepest earthquakes occur?
SUBDUCTION boundaries
Name 3 parts of a seismograph:
bell drum pen (PEN does not move)
What's the minimum # of seismograph stations needed to pinpoint an epicenter?
3
What can 1 seismograph station determine by itself?
Earthquake distance from THAT station and magnitude
What data helps scientists locate a seismic gap?
foci of previous earthquakes along fault
Richter Scale measures:
magnitude (strength) of earthquake
What is the difference between a Richter 4 and Richter 6 earthquake (in terms of energy)?
Richter 6 is (31x31) times stronger than Richter 4
Where does Mohorovicic discontinuity occur?
Between the crust and mantle
What causes most major earthquakes?
Strain that builds up along faults (boundaries) that is then released when plates shift
P Waves
Primary (first); fastest; travel through any substance (dirt, air, liquid, rock)
S Waves
secondary; slower than P-Waves; cannot travel through liquid/gas; cause rocks to move at RIGHT ANGLES to the wave direction
Surface waves
travel on Earth's surface;slower than P or S waves
What is the shadow zone?
wide belt on opposite side of Earth than the earthquake; no waves travel here
What is separated at TRANSITION ZONE?
upper mantle from denser lower mantle
Aftershocks:
can have more than 1000/day; decrease in frequency over time
New Madrid, Missouri
1 of the most seismically active places in the world! No boundaries are here either -- how odd!
What happens when a tsunami approaches shallow water?
Speed slows down but height increases!