Natty D Test 3 Earthquakes

Front 1

What are earthquakes?

Back 1

Earthquakes are a shaking and vibration of the land surface.

Front 2

When rocks break during brittle failure, they release stored up elastic strain energy as
__________ and _____________

Back 2

Heat and Seismic waves

Front 3

As seismic waves pass through Earth material they ____________________

Back 3

elastically distort it

Front 4

Once a seismic wave has passed through Earth material what does it do?

Back 4

It returns to its initial shape

Front 5

The point of initiation of an earthquake within the Earth’s crust is called the

Back 5

Hypocenter or focus

Front 6

The point lying on the Earth’s surface vertically above the point of initiation of an earthquake in the Earth’s interior is called the

Back 6

Epicenter

Front 7

Seismic waves travel outward from the site of initial rupture along a fault in a

Back 7

spherical fashion.

Front 8

Seismic waves are waves of energy produced by fault rupture. They grow ______________________ the further they are from the site of rupture.

Back 8

Weaker

Front 9

What are the names of the two major groups of seismic waves?

Back 9

Body and Surface waves

Front 10

Body waves differ from surface waves in what way?

Back 10

Body waves travel through the Earth’s interior while surface waves travel along the surface of the Earth

Front 11

P‐waves travel ____________________ than S‐waves

Back 11

faster

Front 12

. P‐waves are a series of ________________________________ and ________________ in the direction that the wave is moving or poragating.

Back 12

Contractions, expansions

Front 13

P‐waves travel through ______________, __________________, and ____________.

Back 13

Solids, liquids, gases

Front 14

S‐waves differ from P‐waves as they produce _______________ changes rather than volumetric changes.

Back 14

shape

Front 15

Particles are displaced at ____________ angles to the direction in which an S‐wave propagates.

Back 15

Right

Front 16

Liquids and gases can’t support a shape change.  Can S‐waves propagate through such material?

Back 16

No

Front 17

Surface waves travel along the land surface.  In this course we discussed two major varieties of surface waves.  What are the names of these two major varieties of surface waves?

Back 17

Raliegh and Love

Front 18

Rayleigh waves are said to resemble an _______________ wave.  One important characteristic
of both ocean and Rayleigh waves is that they ______ ______ with depth.

Back 18

ocean... die out

Front 19

Love waves displace particles with a __________________ motion in a plane parallel to the surface of the Earth.

Back 19

Snake‐like

Front 20

What types of seismic wave are most destructive to buildings?

Back 20

Surface Waves (love and rayleigh)

Front 21

Which waves come first?

Back 21

P waves, then S waves

Front 22

What is the interval between P and S waves?

Back 22

S-P Interval

Front 23

What is the minimum number of seismic stations needed to find the epicenter of an earthquake?

Back 23

3

Front 24

What part of seismogram is used to determine the epicenter?

Back 24

The S-P Interval

Front 25

Given two seismic stations, one located at 1000 km and the other at 400 km from the epicenter of an earthquake.  Would the S‐P interval be larger or smaller at the station located 1000 km
from the epicenter?

Back 25

Larger

Front 26

The Richter magnitude is determined by measuring the height of the peak amplitude on a seismogram derived from a Ward‐Anderson seismometer.  The size of the peak amplitude must be scaled to what distance from the epicenter?

Back 26

100km

Front 27

The Richter magnitude scale is

Back 27

logarithmic

Front 28

A Richter magnitude of 3 would be how many times larger than a magnitude 1 earthquake?

Back 28

100 times

Front 29

There is a 32‐fold increase in energy in going from one Richter unit to the next.  What is the energy difference in going from a magnitude 1 to a magnitude 3 earthquake?

Back 29

32 x 32 = 1024

Front 30

What does the equation Mo = µSd represent?

Back 30

The moment of an earthquake

Front 31

In the equation Mo = µSd, what are the parameters µ, S, and d?

Back 31

µ = the shear strength of the faulted rock, S = the area of the fault surface that ruptured,
d=the average displacement across the fault.

Front 32

What does the term Mw in the following equation represent Mw = (2/3)log10(Mo)-10.7?

Back 32

Momentum magnitude

Front 33

Select from the following list the three largest recorded moment magnitudes.

Back 33

Chile, 1960, Alaska, 1964, Sumatra, 2004

Front 34

A great earthquake will have a magnitude between

Back 34

8 or larger

Front 35

Minor to light earthquakes will have a magnitude between

Back 35

3 - 4.9

Front 36

Strong to moderate earthquakes are common in California.  What is the range of magnitudes for
such earthquakes?

Back 36

5 - 6.9

Front 37

Along what kind of plate boundary would you expect major to great earthquakes to occur?

Back 37

Convergent Boundaries

Front 38

How many earthquakes, on average, with magnitudes less than 2.5 occur globally ?

Back 38

900,000

Front 39

How often on a global scale do great earthquakes occur?  Once every

Back 39

5-10 years

Front 40

The modified Mercalli scale was developed to measure the effect of an earthquake on
________________ and _________________.

Back 40

people and buildings

Front 41

The modified Mercalli scale varies from ________ to ________.

Back 41

I, XII

Front 42

Mercalli scale indices of VI or lower measure the effects of an earthquake on

Back 42

People

Front 43

Mercalli scale indices of VII and higher measure the effects of an earthquake on

Back 43

Buildings