Chapter 16

Question 1

What is an Earthquake?

Answer 1

A trembling or shaking of the ground caused by the sudden release of energy stored in the rocks beneath the earth’s surface.

Question 2

WHat is a focus when it comes to an earth quake?

Answer 2

The point within the earth where seismic waves first originate.

Question 3

What is an epicenter?

Answer 3

The point on earth’s surface directly above the focus of an earthquake.

Question 4

What are body waves?

Answer 4

Seismic waves that travel through earths interior.

Question 5

What is a p Wave?

Answer 5

A compressional wave in which rock vibrates parallel to the direction of wave propagation. Think of the slinky analogy.

Question 6

What is an s Wave or a secondary wave?

Answer 6

A seismic wave propagated by a shearing motion, which causes rock to vibrate perpendicular to the direction of wave propagation. THink of the rope analogy not the slinky.

Question 7

What are Love Waves?

Answer 7

they are an as wave but they move side to side rather than up and down.

Question 8

What is a Rayleigh Wave?

Answer 8

A type of surface seismic wave that behaves like a rolling ocean wave adn causes the ground to move in an elliptical path.

Question 9

What is a seismometer?

Answer 9

An instrument used to measure seismic waves.

Question 10

What is a travel-time curve.

Answer 10

A plot of seismic wave arrival times against distance.

Question 11

What is an earthquakes intensity?

Answer 11

A measure of an earthquakes size by its effect on people and buildings.

Question 12

What is the modified Mercalli scale?

Answer 12

Scale expressing intensities of earthquakes in roman numbers ranging from I to XII

Question 13

What is the Richter Scale?

Answer 13

A numerical scale of earthquake magnitudes.

Question 14

What is a seismograph?

Answer 14

The recording device for a seismometer.

Question 15

WHat is a seismogram?

Answer 15

The paper record of earth vibrations.

Question 16

What is the Moment Magnitude?

Answer 16

An earthquake magnitude calculated from the strength of the rock, surface area of the fault rupture, and the amount of rock displacement along the fault.

Question 17

What is liquifaction?

Answer 17

When water saturated soil or sediment turns from a solid to a liquid as a result of earthquake shaking.

Question 18

What is a Foreshock?

Answer 18

Small quakes that precede a main shock.

Question 19

What is a Tsunami?

Answer 19

Huge ocean wave produced by displacement of sea floor; also called seismic sea wave.

Question 20

What is a Benioff Zone?

Answer 20

Distinct earthquake zone that begins at an oceanic trench and slopes landward and downward into earth at an angle of about 30 to 60 degrees.

Question 21

What types of earthquakes occur at divergent plate boundaries?

Answer 21

Shallow and low magnitude.

Question 22

were are transform faults found?

Answer 22

On the ocean floor.

Question 23

What is a precursor

Answer 23

A slight change in the rock next to a fault before the rock breaks or moves due to an earthquake.

Question 24

What are microseisms?

Answer 24

Small tremors caused by small cracks opening within rock. Usually these are precursors to earthquakes.

Question 25

What is Paleoseismology?

Answer 25

digging a trench across the fault zone to examine sedimentary layers that have been offset and discovering the recurrence period of that fault.

Question 26

What are seismic gaps?

Answer 26

A gap where earthquakes have not accrued for a long time.