Natural Disasters (Chapter 3)

down

A normal fault occurs when the hanging wall moves ________ relative to the footwall.

True

Earthquake intensity scales such as the Modified Mercalli scale assess the effects on people and buildings.

sudden earth movements along faults

Earthquakes are most commonly caused by ______________.

normal faults

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 __________.

True

For magnitudes above about 6, the bigger earthquake magnitude means that more people in a larger area and for a longer time will experience the intense shaking.

False

Normal faulting occurs when the hanging wall moves upward relative to the footwall.

True

P and S waves do not follow simple paths as they pass through Earth; they speed up, slow down, and change direction, and S waves even disappear when they reach Earth's core.

gases, liquids, and solids

P waves can travel through ________________.

Love and Rayleigh

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

P

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

the longer the delay is between the arrival of the P waves and S waves

The farther away a seismic station is from an earthquake's hypocenter the __________.

True

The largest moment magnitudes measured to date are from earthquakes that occurred in subduction zones.

epicenter

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

False

The point where a fault first ruptures underground is known as the epicenter.

True

The shaking produced by Rayleigh waves causes both vertical and horizontal movement.

False

The time of day an earthquake strikes is not a critical factor affecting loss of life from the event.

True

Transform faults usually link spreading centers or connect spreading centers with subduction zones.

3

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

strike-slip

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

Surface waves

Which of the following wave types travels slowest through rock?

reverse

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

Reverse

________ faults are commonly found at areas of plate convergence where subduction or continental collision occurs.