# EARTHQUAKES Practice for 6 th grade quiz Ms. Cooper’s class Korematsu Elementary School.

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EARTHQUAKES Practice for 6 th grade quiz Ms. Cooper’s class Korematsu Elementary School

What does the term “plastic” mean when describing the upper mantle?

Able to change shape without breaking

What is a fault?

A place on the Earth’s surface that breaks during an earthquake

Describe “stick-slip motion” and tell what it causes.

When the crust of two plates are stuck on each other. Energy builds up and they suddenly slip causing an earthquake

What kind of energy builds up when the crust of two plates are stuck while the upper mantle keeps moving?

Potential Energy

What is the point below the surface where rock breaks causing an earthquake called?

The Focus

What do we call the point on the Earth’s surface during an earthquake where the seismic waves are the strongest?

The Epicenter

Where do shallow focus earthquakes occur?

In the crust less than 50 km below the surface

Where do deep focus earthquakes occur?

At subduction zones when the plate breaks

What is a “slickensides”?

Exposed rock that has been polished from another mass of rock moving against it

Why is it better to have frequent earthquakes along a transform plate boundary than seldom?

If earthquakes happen frequently, the potential energy can not build up too high and there is less damage.

Why do aftershocks occur?

Because not all of the potential energy is released in a quake

What is an instrument that measures seismic waves called?

A seismograph

How do seismologists locate the epicenter of an earthquake?

The difference between arrival time of P and S waves are measured at THREE seismic stations The distance of the quake from each station is calculated A circle with the radius of that distance is drawn around each station on a map The point where all three circles cross is the epicenter

Which scale rates an earthquake by the size of its seismic waves?

The Richter Scale

Which scale rates the damage suffered by buildings, the ground and people during a quake?

The Mercalli Intensity Scale