VOCAB GHC Ch 3: Earthquake Geology and Seismology

Question 1

acceleration

Answer 1

(1) To cause to move faster. (2) The rate of change of motion.

Question 2

aftershock

Answer 2

A smaller earthquake following a mainshock on the same section of a fault. Aftershocks can continue for years following a large mainshock.

Question 3

amplitude

Answer 3

The maximum displacement or height of a wave crest or depth of a trough.

Question 4

base isolation

Answer 4

Protecting buildings from earthquakes ny isolating the base of the building form the shaking ground via rollers, shock absorbers, etc.

Question 5

body waves

Answer 5

Seismic wave that travels through the body of the earth– for example, primary and secondary waves.

Question 6

compression

Answer 6

A state of stress that causes a pushing together or contraction.

Question 7

cross-section

Answer 7

A two-dimensional drawing showing features in the vertical plane, as in a canyon wall or road cut.

Question 8

dip

Answer 8

The angle of inclination measured in degrees from the horizontal.

Question 9

dip-slip fault

Answer 9

Fault where most of the movement is either up or down in response to pushing or pulling.

Question 10

fault

Answer 10

A fracture or belt of fractures where the two sides move past each other.

Question 11

footwall

Answer 11

The underlying side or block of a fault.

Question 12

foreshock

Answer 12

A smaller earthquake that precedes a mainshock on the same section of a fault.

Question 13

facture

Answer 13

A general term for any breaks in rock. Fractures include faults, joints, and cracks.

Question 14

frequency

Answer 14

Number of events in a given time interval. For earthquakes, it is the number of cycles of seismic waves that pass in a second; frequency = 1/period.

Question 15

friction

Answer 15

The resistance to motion of two bodies in contact.

Question 16

granite

Answer 16

A quartz-rich plutonic rock.

Question 17

hangingwall

Answer 17

The overlying side or block of a fault.

Question 18

hertz (Hz)

Answer 18

One hertz equals one cycle per second.

Question 19

hypocenter

Answer 19

The initial portion of a fault that moved to generate an earthquake.Hypocenters are below the ground surface; epicenters are above them on the surface.

Question 20

inertia

Answer 20

The property of matter by which it will remain at rest unless acted on by an external force.

Question 21

joint

Answer 21

A fracture or parting in rock.

Question 22

law of original continutiy

Answer 22

A water-laid sediment body continues laterally in all directions until it thins out do to nondeposition or butts against the edge of the basin of deposition.

Question 23

law of original horizontality

Answer 23

Sediments are deposited in nearly horizontal layers.

Question 24

law of superposition

Answer 24

In a sequence of sedimentary rock layers, the oldest layer is at the base, and ages are progressively younger to the top.

Question 25

left-lateral fault

Answer 25

A strike-slip fault where most of the displacement is toward the left hand of a person straddling the fault.

Question 26

magnitude

Answer 26

An assessment of the size of an an event.

Question 27

mainshock

Answer 27

The largest earthquake in a sequence.

Question 28

map

Answer 28

A two-dimensional representation showing the features in a near-horizontal surface, such as the ground.

Question 29

normal fault

Answer 29

A dip-slip fault in which the upper fault block has moved downward in response to tensional stress.

Question 30

period

Answer 30

The length of time for a complete cycle of seismic waves to pass; equals 1/frequency.

Question 31

permeability

Answer 31

The capacity of a porous material to transmit fluids.

Question 32

primary (P) wave

Answer 32

The first seismic wave to reach a seismometer. Movement is by alternating

Question 33

resonance

Answer 33

The act of resounding, ringing.

Question 34

retrofit

Answer 34

Reinforcement or strengthening of an existing building or other structure.

Question 35

reverse fault

Answer 35

A dip-slip fault where the upper fault block has moved upward in response to compressional stresses.

Question 36

right-lateral fault

Answer 36

A strike-slip fault where most of the displacement is toward the right hand of a person straddling the fault.

Question 37

secondary (S) wave

Answer 37

Second seismic wave to arrive at the seismometer. S waves move only through solid bodies.

Question 38

seism

Answer 38

Earthquake

Question 39

seismic moment

Answer 39

A measure of earthquake size that involves amount of movement on the fault, the shear strength of the rocks, and the area of fault rupture.

Question 40

seismic wave

Answer 40

A general term for all waves generated by earthquakes.

Question 41

seismogram

Answer 41

The record made by a seismograph.

Question 42

seismograph

Answer 42

An instrument that records vibrations of the Earth.

Question 43

seismology

Answer 43

The study of seismic waves generated by earthquakes.

Question 44

seismometer

Answer 44

An instrument that detects Earth motions.

Question 45

shear

Answer 45

The failure of a body where the mass on one side slides past the portion on the other side.

Question 46

stress

Answer 46

External forces acting on masses or along surfaces; forces include shear, tension, and compression.

Question 47

strike

Answer 47

The compass bearing of the trend of a rock layer as viewed in the horizontal plane.

Question 48

strike-slip fault

Answer 48

Fault where most of the movement is horizontal or slide-past in character.

Question 49

surface waves

Answer 49

A class of seismic waves that travel along the surface only-- for example, Love and Rayleigh waves.

Question 50

tension

Answer 50

A state of stress that tends to pull a body apart.

Question 51

transform fault

Answer 51

A strike-slip fault that connects the ends of two offset segments of plate edges, such as spreading centers or subduction zones.

Question 52

wavelength

Answer 52

The distance between two successive wave peaks, or troughs, in seismic waves or ocean waves.