Chapter 3

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The Richter scale is set up so that for every _______ increase in the amplitude of the recorded seismic wave, the Richter magnitude increases one number, e.g., from 4 to 5.

10-fold

Using the S-P timing method, epicenters can be located using seismograms from a minimum of ______ recording stations.

3

Which of the following is not a divergent margin?

Aleutian Island Arc

When the part of California west of the San Andreas Fault plows into Alaska it will __________.

Become part of Alaska's southern margin

How does a locked zone in a fault typically catch up with a creeping section?

By infrequent but large fault movements

Three basic classes of collisions include all but which of the following?

Continental plate versus mantle plate

The point on Earth's surface directly above the point where the fault first ruptures is called the ____________.

Epicenter

Several recent earthquakes in Washington's Puget Sound region were caused by movement of the subducting ______________ Plate.

Juan de Fuca

Seismic waves that travel only near Earth's surface are of two main types: _________ waves.

Love and Rayleigh

The _____ wave travels fastest and moves in a push-pull fashion of alternating pulses of compression (push) and extension (pull).

P

__________ are the down-dropped areas in the middle of spreading-center domes that are being pulled apart.

Rift Valleys

The New Madrid earthquakes are apparently related to an old buried ____________.

Rift Zone

When most of the movement along a fault is horizontal, the fault is referred to as a __________ fault.

Strike-slip

The intensity of an earthquake is influenced by all but which of the following?

The current air pressure

In the 1989 Loma Prieta quake, the Marina District building collapses were extensive, and numerous destructive fires broke out, due to all but which one of the following?

Widespread looting and arson

At Hebgen Lake in 1959 an earthquake larger than magnitude 7 greatly affected ____________.

Yellowstone National Park

a) How many of the 17 earthquakes listed occurred at subduction zones? b) How many of the 17 earthquakes listed occurred at a Pacific Plate boundary? c) How many of the 17 earthquakes listed occurred in the 21st century?

a) 15 b) 8 c) 6

The Charleston, South Carolina, earthquake of 1886 occurred along a seismic belt that may be related to _________________.

an adjacent oceanic fracture zone on the Atlantic seafloor

In general, during an earthquake you should __________.

drop, cover, and hold on where you currently are

The best time for an earthquake to occur to minimize loss of life is __________.

during the night when most people are home and asleep

Earthquakes in Hawaii are mostly related to ________________.

movement of volcanic magma beneath the ground

Faults on which the dominant forces are extensional are recognized by the separation of the pulled-apart rock layers in a zone of omission; these are __________.

normal faults

Most earthquakes are explainable using __________.

plate-tectonics theory

With compressional forces, the hanging wall moves upward relative to the footwall; this type of fault is referred to as a __________ fault.

reverse

The strike-slip San Andreas Fault in California is a _______ fault more than 1,300 km long.

right-lateral

Earthquakes are most commonly caused by ______________.

sudden earth movements along faults

The greatest earthquakes in the world occur _____________.

where plates collide with each other