Earthquakes

About __ earthquakes occur each year.

75

What do scientists call an area along a fault where no earthquake activity has occurred for a long time?

A seismic gap

What kind of structure is least likely to be damaged in a major earthquake?

Reinforced steel-frame building

based on the amplitude of the largest seismic wave recorded on a seismogram

Richter scale

what two types of measurement do scientists use to describe the size of earthquakes?

Richter scale and Momentum magnitude

_ waves shake particles at right angles to their direction of travel.

S

The ___ _______ is one of the most studied fault systems in the world.

San Andreas

What is fault creep?

a slow gradual movement

the vibration of Earth produced by the rapid reduction of energy

earthquake

The _______ _______ hypothesis states that when rocks are deformed, they bend and then break, releasing stored energy.

elastic rebound

the location on the surface directly above the focus

epicenter

True or False? Most earthquakes generate tsunamis.

false

True or False? On a seismogram, the greater the interval is between the arival of the first P wave and the first S wave, the greater the distance to the earthquake source.

false

True or False? Scientists are able to make accurate long-term predictions based on their understanding of how earthquakes occur.

false

True or False? You can use travel-time graphs from two seismographs to find the exact location of an earthquake epicenter.

false

a large fracture in Earth's mantle and crust

fault

the point within Earth where the earthquake starts

focus

measure of the amount of earthquake shaking at a location based on damage

intensity

During an earthquake, violent shaking can cause soil and rock on slopes to move, resulting in __________.

landslides

List three factors that affect the degree of damage that occurs to structures as a result of earthquakes.

landslides, ground subsidence, and fires

measure of the size of seismic waves or amount of energy released at the earthquake source

magnitude

What measure do scientists today use for earthquakes?

momentum magnitude

derived from the amount of displacement that occurs along a fault zone

momentum magnitude scale

energy that radiates in all direction from the earthquake origin

seismic wave

The sinking of the ground caused by earthquake vibrations is called ground __________.

subsidence

True or False? It was not until the 1906 San Francisco earthquake was studied that the actual cause of earthquakes was understood.

true

True or False? Methods used to make short-range earthquake predictions have not been successful.

true

True or False? Most earthquakes occur along existing fault lines.

true