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Chapter 6 - Earthquakes
n/a
37
Geology
Undergraduate 3
11/04/2011

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Term
Define Earthquakes:
Definition
shaking and vibration of the land surface
Term
When rocks break during brittle failure, they release stored up elastic strain energy as _________ and _______ _________.
Definition
Heat, seismic waves
Term
As seismic waves pass through Earth material they ___________ distort it.
Definition
Elastically
Term
The point of initiation of an earthquake within the Earth's crust is called the _____________ or __________.
Definition
Hypocenter, Focus
Term
The point of lying on the Earth's surface vertically above the point of initiation of an earthquake in the Earth's interior is called the:
Definition
Epicenter
Term
Seismic waves travel outward from the site of initial rupture along a fault in a ___________ fashion.
Definition
spherical
Term
Seismic waves are waves of energy produced by fault rupture. They grow _________ the further they are from the site of rupture.
Definition
weaker
Term
What are the names of the two major groups of seismic waves?
Definition
Body and surface
Term
Body waves differ from surface waves in what way?
Definition
Body waves travel through interior while surface waves travel along surface
Term
P-waves travel ____________ than S-waves.
Definition
faster
Term
P-waves are a series of ________ and ___________ in the direction that the wave is moving or poragating.
Definition
Contractions, expansions
Term
P-waves travel through ____________,__________, and _____________.
Definition
Solids, liquids, gases
Term
S-waves differ from P-waves as they produce _________ changes rather than volumetric changes
Definition
shape
Term
Particles are displaced at __________ angles to the direction in which and S-wave propagates.
Definition
right
Term
Liquids and gases can't support a shape change. Can S-waves propagate through such material?
Definition
no.
Term
Surface waves travel along the land surface. In this course we discussed two major varieties of surface waves. What are the names of these two major varieties of surface waves?
Definition
Love and Rayleigh
Term
Rayleigh waves are said to resemble an ___________ wave. One important characteristic of both is that they ____ ______ with depth.
Definition
Ocean, die out :(
Term
Love waves displace particles with a _____________ motion.
Definition
snake-like
Term
What types of seismic wave are most destructive to buildings?
Definition
Surface (love or rayleigh)
Term
What is the interval between P and S waves called?
Definition
S-P interval
Term
What is the minimum number of seismic stations needed to find the epicenter of an earthquake?
Definition
3
Term
What part of a seismogram is used to determine the epicenter?
Definition
the S-P interval
Term
Given two seismic stations, one located at 1000 km and the other at 400 km from the epicenter of an earthquake. Would the S-P interval be larger or smaller at the station located at 1000 km from the epicenter?
Definition
Larger
Term
The Richter magnitude is determined by measuring the height of the peak amplitude on a seismogram derived from a Ward-Anderson seismometer. The size of the peak amplitude must be scaled to what distance from the epicenter?
Definition
100 km
Term
The Richter magnitude scale is:
Definition
Logarithmic
Term
A Richter magnitude of 3 would be how many times larger than a magnitude of 1?
Definition
100! :D
Term
What are the three largest recorded moment magnitudes?
Definition
Chile, 1960
Alaska, 1964
Sumatra, 2004
Term
A great earthquake will have a magnitude between...
Definition
8 or larger
Term
A minor to light earthquake will have a magnitude between...
Definition
3 - 4.9
Term
Strong to moderate earthquakes are common in CA. What is the range of magnitudes for such?
Definition
5 - 6.9
Term
Along what kind of plate boundary would you expect major to great earthquakes to occur?
Definition
convergent boundaries
Term
How many earthquakes on average with magnitudes less than 2.5 occur globally?
Definition
900,000
Term
How often on a global scale do great earthquakes occur?
Definition
Once every 5 - 10 years
Term
The modified Mercalli scale was developed to measure the effect of an earthquake on _________ and ____________.
Definition
People, buildings
Term
The modified Mercallli scale vaires from _____ to ______.
Definition
I, XII
Term
Mercalli scale indices of VI or lower measure the effects of an earthquake on ________.
Definition
People
Term
Mercalli scale indices of VII and higher measure the effects of an earthquake on ________.
Definition
Buildings
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