# Earthquakes 2022

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Seismograph

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35 Terms

Seismograph

A device that records ground movements caused by seismic waves as they move through Earth.

Seismologist

A scientist who studies earthquakes.

On a seismograph the suspended mass...

stays at rest while the frame and drum move with the earth.

earthquake magnitude

measure of ground shaking during and earthquake, which depends of distance from epicenter and the geological material.

earthquake intensity

Measure of damage from an earthquake.

S waves (secondary waves)

Seismic waves that shake the ground at right angles compared to the direction of motion. Also, will end when they strike the earth's outer core as it is a liquid.

P waves (Primary waves)

Are body waves that travel through the interior of the Earth. Shake the ground in the same direction as the wave is travelling. Can travel through solids and liquids. The fastest seismic wave type.

Modified Mercalli Scale

Scale that rates earthquake intensity

Richter scale

Scale that measures energy released by a quake

stress

Forces per unit area acting on a material or layers of rock.

fault

Fracture in rock along which movement occurs

tsunami

Wave generated by vertical motions of the seafloor

seismic gap

Section of an active fault that has not experienced a significant earthquake for a long time

surface wave

Seismic wave that causes the ground to move in two directions

How many seismic stations are necessary to find the epicenter of an earthquake?

At least 3.

The fact that a significant earthquake has not occurred within a seismic gap indicates that an earthquake is more likely to occur in the near future.

True

Movement occurs along fractures in rocks when

stress overcomes the strength of the rocks involved

The stress which causes a material to twist is known as

shear

The stress which causes a material to pull apart is known as

tension

P-waves and S-waves are also known as

body waves

Epicenter

Point on Earth's surface directly above an earthquake's focus. Location of the most intense damage. Location of the highest magnitude of shaking.

Focus

The point of failure where the waves originate.

Seismic Gap

A location where a city is located over a fault but has not experienced an earthquake in a long time.

San Andreas Fault

Strike Slip Fault

Reverse Fault

formed from compression. Found in mountains.

seismic belts (seismic zones)(Ring of Fire)

The relatively narrow strips of crust on Earth under which most earthquakes occur

locations of seismic belts are determined by

plotting earthquake epicenters

Deaths associated with earthquakes in sloping areas can result from

landslides, avalanches

Seismic waves change speed and direction when they encounter different materials.

True

P-waves travel through Earth's mantle.

True

Surface waves will arrive first at any location.

False

As you travel farther from the epicenter of an earthquake...

seismic waves are spread farther apart.

moment magnitude scale

A numerical scale of earthquake magnitude that takes into account the size of the fault rupture

The scale that uses roman numerals.

Mercalli Scale

As the distance from a quake's epicenter increases...

intensity and magnitude decrease.