Chapter 6a: Earthquakes Review Questions

The two types of seismic surface waves are

L waves and R waves

Today, seismologists describe earthquakes using the ____________ scale.

Moment magnitude

Which of the major subdivisions of Earth's interior is thought to be liquid?

Outer core

The two types of seismic body waves are

P waves and S waves

The greatest frequency of large earthquakes occurs along a relatively narrow zone around the edge of the Pacific Ocean known as the

Ring of Fire

Which type of body wave can be transmitted through solids but not fluids?

S waves

Most of the destruction produced by earthquakes is associated with ______ waves.

Surface

An earthquake is the vibration of Earth produced by the rapid release of energy.

True

P waves can travel through solids, liquids, and gases.

True

S waves can only travel through a solid medium.

True

The continental crust is much thicker than the oceanic crust.

True

The distance between a seismological recording station and the earthquake source is determined from arrival times of P and S waves.

True

The epicenter of an earthquake is located on Earth's surface directly above the focus.

True

The oceanic crust has a composition similar to the rock basalt.

True

Travel-time graphs are used to determine the distances to earthquakes.

True

The Moho is a boundary that separates the mantle and crust.

True (Mohorovicic Discontinuity)

The energy released by an earthquake is a measurement referred to as

amplitude

The very viscous layer of the Earth located directly below the lithosphere is the

asthenosphere

The thinnest layer of Earth is the

crust

List the four major subdivisions of Earth's interior.

crust, mantle, outer core, inner core

The mechanism by which rocks store and eventually release energy to produce an earthquake is called

elastic rebound

An earthquake is the vibration of the Earth produced by the rapid release of

energy

The principle of a seismograph is based on the ______of a suspended mass.

inertia

Earth's inner core is thought to consist predominantly of ________ and ____________

iron & nickel

The two types of motion of surface waves are

lateral and ripple

The Earth's outer core is composed of

liquid

The boundary between the crust and the mantle is the

lithosphere

The rigid layer of Earth that consists of the crust and uppermost mantle is called the

lithosphere

Earthquakes frequently are associated with large fractures in the Earth called

tectonic plates

Tsunamis are produced by ______________ on the ocean floor.

underwater earthquakes at plate boundaries

An increase of one unit of magnitude on the Richter scale means that the release of energy will be _____ times greater.

10

The method by which seismographs are used to determine the magnitude of an earthquake was developed by

Charles Richter

The position on the Earth's surface directly above the earthquake source is called the

Epicenter

All of the major earthquakes in the United States have occurred in coastal regions.

False

Seismographs can only detect earthquakes within 500 miles of the instrument.

False

The energy released during an earthquake can be detected for at most a few minutes.

False

Tsunamis travel through solids, liquids, and gases

False

When an earthquake occurs, energy radiates in all directions from its source. The source of the earthquake is also referred to as the center of inertia.

False --Epicenter

S waves are the same as surface waves.

False → an S wave is a type of body wave

The lithosphere is a plastic layer located in the mantle.

False → asthenosphere

Most of our knowledge about Earth's interior comes from deep-sea drilling.

False → from seismic waves caused by earthquakes, explosions, bombs, etc.

An increase of one on the moment magnitude scale corresponds to an increase of about ten in energy.

False → increase of about 32 in energy

Earth's inner core is thought to consist predominantly of two elements: oxygen and nitrogen.

False → iron and nickel

The moment magnitude of an earthquake measures the time of the earthquake.

False → measures total energy of all waves of earthquake

Earth's outer core is solid; the inner core behaves as a liquid.

False → outer core is liquid and inner core is solid

Overall, P type seismic wave is the most destructive.

False → surface waves

In most earthquakes, P waves are the most destructive

False → surface waves are the most destructive

When examining a typical seismic record, we find surface waves arriving before body waves.

False → surface waves arrive last

The greatest frequency of earthquake activity occurs in a relatively narrow belt surrounding the Atlantic Ocean.

False → surrounding the Pacific Ocean

The source of an earthquake is known as the

Focus

The mineral composition of the oceanic crust is similar to the rock

basalt

P-type seismic waves cause rock to move with a

push-pull motion

The change in direction of a seismic wave is referred to as

refraction

The instrument used to record the vibrations generated by earthquakes is called a(n)

seismograph

The part of the earth on the opposite side of the earthquake that does not experience S waves is known as a

shadow zone

S type seismic waves have a

shake motion