Chapter 11 Earthquakes And Earthquake Hazards

Front 1

Earthquake

Back 1

Vibration of Earth produced by the rapid release of energy

Front 2

focus (hypocenter)

Back 2

The zone within Earth where rock displacement produces an earthquake

Front 3

epicenter

Back 3

The location on Earth's surface that lies directly above the focus of an earthquake.

Front 4

seismic waves

Back 4

a form of energy that causes the material that transmits them to shake

Front 5

Elastic rebound

Back 5

The sudden release of stored strain in rocks that results in movement along a fault.

Front 6

aftershocks

Back 6

A smaller earthquake that follows the main earthquake.

Front 7

foreshocks

Back 7

Small earthquakes that often precede a major earthquake.

Front 8

Who was first to explain the mechanism by which most earthquakes are generated

Back 8

H F Reid of Johns Hopkins University

Front 9

How are faults, hypocenters and epicenters related

Back 9

They are all caused by earthquakes

Front 10

megathrust fault

Back 10

The plate boundary separating a subducting slab of oceanic lithosphere and the overlying plate.

Front 11

Fault creep

Back 11

Gradual displacement along a fault. Such activity occurs relatively smoothly and with little noticeable seismic activity.

Front 12

What type of fault creates the most destructive earthquakes

Back 12

Megathrust faults

Front 13

fault slip

Back 13

The amount of displacement on the fault surface

Front 14

The study of earthquakes

Back 14

seismology

Front 15

seismographs or seismometers

Back 15

An instrument that records earthquake waves.

Front 16

inertia

Back 16

A property by which objects at rest tend to remain at rest, and objects in motion tend to stay in motion unless either is acted upon by an outside force.

Front 17

A record made by a seismograph. Records 2 types of waves body waves and surface waves

Back 17

seismogram

Front 18

2 types of body waves

Back 18

Primary (p waves) and Secondary (s waves) waves

Front 19

Primary (P) Waves

Back 19

A type of seismic wave that involves alternating compression (push) and expansion (pull) of the material through which it passes. temporarily changes the volume of the material that transmits them

Front 20

Secondary (S) Waves

Back 20

A seismic wave that involves oscillation (movement back and forth) perpendicular to the direction of propagation. Only moves through Solids and temporarily changes the shape of the material that transmits them

Front 21

Seismic waves that travel along the outer layer of Earth.

Back 21

surface waves

Front 22

Which type of seismic wave tend to cause the greatest destruction to buildings?

Back 22

Surface waves

Front 23

Which of the 3 waves creates the greatest amplitude

Back 23

Surface Waves

Front 24

What 2 methods do seismologist use to determine the size of an earthquake?

Back 24

Intensity and magnitude

Front 25

How much more energy does a magnitude 7.0 earthquake release than 6.0 earthquake?

Back 25

32 times more energy

Front 26

Intensity (earthquake)

Back 26

A measure of the degree of earthquake shaking at a given locale, based on the amount of damage.

Front 27

magnitude (earthquake)

Back 27

An estimate of the total amount of energy released during an earth-quake, based on seismic records.

Front 28

modified mercalli intensity scale

Back 28

A 12-point scale developed to evaluate earthquake intensity, based on the amount of damage to various structures.

Front 29

Richter Scale

Back 29

A scale of earthquake magnitude based on the amplitude of the largest seismic wave.

Front 30

moment magnitude

Back 30

A more precise measure of earthquake magnitude than the Richter scale that is derived from the amount of displacement that occurs along a fault zone. *(estimates the total energy reed so it is better for measuring large earthquakes compared to the richter scale)*

Front 31

List four factors that affect the amount of destruction that seismic vibrations cause to human-made structures

Back 31

1) The intensity

2) the duration of the vibrations

3) the nature of the material upon which structures rest

4) the nature of building materials and construction practices of the region

Front 32

List 3 types of destruction associated with earthquakes besides seismic vibrations

Back 32

Landslides, fire, and tsunamis

Front 33

seismic sea wave

Back 33

Tsunami

Front 34

How is a tsunami formed

Back 34

By major undersea earthquakes that lifts large slabs of the seafloor

Front 35

where does the greatest amount of seismic activity occur

Back 35

along convergent plate boundarys

Front 36

Name 2 major concentration of strong earthquakes activity

Back 36

Along megathrust faults and the alpine Himalayan belt

Front 37

precursors

Back 37

Events or t precede a forth coming earthquake and thus may provide warning

Front 38

Are accurate short range earthquakes predictions currently possible using modern seismic instruments

Back 38

No, there are no reliable methods for short-range earthquake predictions.

Front 39

For each increase of 1 on the Richter scale, seismic wave amplitude increases _____ times.

Back 39

10

Front 40

What is the value of long-range earthquake forecasts?

Back 40

They can be used as guides for where to build things such as dams, roads, etc. and help architects who build large structures to know what types of earthquakes the structure will go through.

Front 41

seismic gaps

Back 41

A segment of an active fault zone that has not experienced a major earthquake over a span when most other segments have. Such segments are probable sites for future major earthquakes.

Front 42

The point within Earth from which earthquake wave energy radiates

Back 42

focus

Front 43

On average, how many damaging earthquakes occur each year?

Back 43

1000

Front 44

Most earthquakes are the result of movement along what

Back 44

faults

Front 45

During the 1906 San Francisco earthquake, the Pacific Plate moved 4.7 meters (15 feet) north relative to the North American Plate. Which of the following types of stress was exerted on the rocks during this earthquake?

Back 45

shear stress

Front 46

what event allows rocks on either side of a fault to rebound elastically, causing an earthquake?

Back 46

friction along a fault plane is overcome

Front 47

A __________ is formed when one slab of rock slides on top of another at an angle less than 45°

Back 47

thrust fault

Front 48

A __________ is formed when one slab of rock slides on top of another at an angle greater than 45°

Back 48

reverse fault

Front 49

A ____________ is formed when one slab of rock slides past another laterally

Back 49

strike-slip fault

Front 50

Divergent boundaries are associated with _________ and _____________ faults

Back 50

normal; strike-slip faults

Front 51

These faults are created by compression, which causes one slab of rock to push on top of another. The compressional forces generate friction along the faults.

Back 51

Thrust and reverse faults

Front 52

These faults are created when bodies of rock slide laterally past each other. The only force that generates friction along a strike-slip fault is the pressure of the rocks.

Back 52

strike slip faults

Front 53

These faults are created when one slab of rock pulls apart from another and slides downward with respect to the other slab. Gravity is the force that generates friction along normal faults.

Back 53

Normal faults

Front 54

rank the three different plate boundary types in terms of the severity of the earthquakes they produce. rank from highest to lowest

Back 54

convergent, transform, and divergent

Front 55

Define earthquake intensity.

Back 55

A qualitative measure of the amount of ground shaking at a certain location.

Front 56

A smaller earthquake in Virginia was felt over a larger distance, as compared to a larger earthquake in California. What is a reason this occurred

Back 56

colder crust

Front 57

Richter magnitude (ML) is derived from measuring __________ and __________, and then plotting them on a Richter diagram.

Back 57

S minus P wave time; maximum S wave height

Front 58

Why is moment magnitude (MW) preferred over Richter magnitude (ML)?

Back 58

Moment magnitude measures the total energy released during an earthquake and can adequately measure the energy of large earthquakes

Front 59

What is a tsunami?

Back 59

a series of water waves that travel away from a fault in all directions at high speed

Front 60

Why do ships at sea tend not to notice tsunamis?

Back 60

Tsunamis in deep water have small wave height and long wavelength.

Front 61

Why does the wave height of a tsunami increase as the tsunami enters shallow water?

Back 61

In shallow water, the energy of the tsunami must be contained within a smaller water column

Front 62

What type of plate boundary are most tsunamis associated with?

Back 62

convergent plate boundaries

Front 63

Which ocean is associated with most tsunamis?

Back 63

Atlantic Ocean

Front 64

Will Sumatra experience another tsunami like the destructive one of December 2004?

Back 64

This is likely, because Sumatra is near many ocean trenches

Front 65

Liquefaction will amplify the power of ________.

Back 65

seismic waves

Front 66

What information is needed when determining the distance from the focus of an earthquake to the seismic receiving station?

Back 66

The time interval between the P and S waves