Deck 9: Earthquakes and Earthapos;s Interior

Question 1

On March 11, 2011 a 9.0-magnitude earthquake and tsunami struck Japan but caused little damage because of their high seawall and strong building codes.

Answer 1

False

Question 2

The second major seismic belt, accounting for 15% of all earthquakes, is the Mediterranean-Asiatic belt.

Answer 2

True

Question 3

The ____________________ is the liquid structural layer of Earth.

Answer 3

outer core

Question 4

If you could drill from the outer surface of Earth all the way to the center, you would pass first through the crust, then through the ____________________, and finally through the _____________________.

Question 5

Larger earthquakes rupture more rocks than smaller earthquakes and rupture usually occurs along a longer segment of a fault and for a longer duration.

Question 6

The opening of large crevasses that open up and swallow people is a significant source of danger created by earthquakes.

Question 7

The ____________________ or focus of an earthquake is the location within the crust where the energy of an earthquake is released. The ____________________ is the point on Earth's surface directly above the focus.

Question 8

The upper mantle and the crust of Earth together constitute the ____________________.

Question 9

We know that the mantle is not molten because P-waves can travel through it.

Question 10

The number of seismograph records needed to locate the epicenter of an earthquake is ____________________.

Question 11

The theory of elastic rebound was proposed as a result of studies following the ____________________ earthquake in the year ____________________.

Question 12

The ____________________ is a layer of Earth's mantle in which the rocks are close to their melting point and are less elastic.

Question 13

Monitoring changes in the electrical resistance of the ground is a scientifically accepted method used to predict earthquakes.

Question 14

Earthquakes occur because rocks are capable of storing unlimited amounts of energy.

Question 15

____________________ is a property of solids, such as rocks, and means that once they have been deformed by an applied force, they return to their original shape when the force is no longer present.

Question 16

The velocities of P- and S-waves are determined by the two properties of the material they are passing through: ____________________ and ____________________.

Question 17

For every integer increase of magnitude on the Richter Scale, ____________________ times more energy is released by the earthquake.

Question 18

Cold rocks have greater elasticity than do hot rocks.

Question 19

The geothermal gradient is not useful for estimating temperatures at great depth.

Question 20

According to elastic rebound theory, rocks deform and bend. When their internal strength is exceeded they rupture. This energy release is called an earthquake.

Question 21

A very small percentage of all earthquakes occur ____.

A)along the Mediterranean-Asiatic Belt
B)along the Circum-Mediterranean Belt
C)within the interiors of plates and spreading-ridge systems
D)along the west coast of South America
E)along the east coast of East Asia in the Pacific Ocean

Question 22

What factor is least likely to affect earthquake intensity?

A)The distance from the epicenter
B)The depth of the hypocenter
C)The population density
D)The duration of shaking
E)The magnitude of the last recorded earthquake

Question 23

A very strong earthquake recorded in North America was the intraplate quake known as the ____ earthquake.

A)1811 New Madrid
B)1886 Boston
C)1906 San Francisco
D)1964 Anchorage
E)1984 Mount St. Helens

Question 24

The foci of most earthquakes are ____.

A)shallow and intermediate
B)shallow and deep
C)intermediate and deep
D)evenly distributed among shallow, intermediate, and deep
E)not able to be determined with present technology

Question 25

As S- and P-waves travel farther, ____.

A)their intensity increases
B)the surface waves catch up
C)they overtake the surface waves
D)the P-S time interval increases
E)the P-S time interval decreases

Question 26

The two types of body waves are ____and ____ waves.

A)Raleigh; Love
B)focal; distal
C)primary; secondary
D)tensional; extensional
E)compressional; extensional

Question 27

P-waves travel faster than S-waves ____.

A)under all circumstances
B)only when the earthquake is generated in Earth's core
C)when the ground surface is dense and elastic
D)when both waves pass through liquid
E)only when Earth's density increases with depth

Question 28

One possible way to decrease the magnitude of an earthquake is to ____.

A)build more earthquake-proof structures
B)replace rigid soil with soil that will liquefy during an earthquake
C)use drilling equipment to dig into fractured rock and release pressure
D)inject fluid into fractured rocks
E)inject concrete into fractured rocks

Question 29

P-waves and S-waves ____.

A)are two types of surface waves
B)are also called Rayleigh waves
C)are also called Love waves
D)cause the individual particles of the material to move back and forth in a horizontal plane perpendicular to the direction of wave travel
E)are the slowest type of seismic waves

Question 30

Intraplate earthquakes ____.

A)occur because continental crust is moving over plutons
B)occur when there is stress caused by compression
C)are well understood
D)account for 20% of earthquakes
E)are usually stronger than earthquakes in plate boundary areas

Question 31

During an earthquake, seismic waves ____.

A)indicate that the danger has passed
B)indicate that the underlying rocks have no elasticity
C)cause shaking and damage to structures
D)last only a few seconds
E)do not play a roll in liquifaction

Question 32

In January 2010 and March 2011, two major earthquakes occurred in ____ and ____.

A)Haiti; Japan
B)Indonesia; Japan
C)Mexico; Haiti
D)Japan; Mexico
E)Indonesia; Mexico

Question 33

____ caused the most damage during the San Francisco earthquake.

A)Fire
B)A tsunami
C)Ground shaking
D)Ground fissures
E)Landslides

Question 34

The P-wave shadow zone ____.

A)is recorded in Earth's core
B)is an area in which a strong P-wave are recorded by seismographs
C)is an area in which little P-wave energy is recorded by seismographs
D)is not observed during all earthquakes
E)has twice the number of P-waves normally observed

Question 35

If the P-S time intervals are known from at least three seismograph stations, the ____ of any earthquake can be determined.

A)focal depth
B)intensity
C)magnitude
D)probability of a tsunami
E)epicenter

Question 36

The magnitude of an earthquake measures ____.

A)intensity
B)damage
C)the energy released
D)the duration of trembling
E)combined amplitude of all tremors recorded

Question 37

Below the outermost layer of Earth lies the ____, which accounts for more than ____ of Earth's volume.

A)core; 30%
B)core; 50%
C)core; 80%
D)mantle; 50%
E)mantle; 80%

Question 38

A seismic risk map can be used to ____.

A)locate the epicenter of the next earthquake in a particular area
B)locate the focus of the next earthquake in a particular area
C)indicate the likelihood and potential severity of future earthquakes
D)accurately predict the time of the next major earthquake
E)predict earthquakes between 4.0 and 7.0 on the Richter Scale

Question 39

Almost ____ % of earthquakes take place along plate boundaries.

A)100
B)95
C)80
D)55
E)25

Question 40

Most earthquakes occur along the circum-Pacific belt primarily because ____.

A)of the convergence along plate margins
B)of the divergence along plate margins
C)Earth's crust is more rigid in these areas
D)P- and S-waves are stronger in those areas due to the greater density of Earth's crust
E)S-waves travel easily through water

Question 41

Seismic wave is a general term encompassing all waves generated by an earthquake. Discuss the different types of seismic waves.

Question 42

Briefly explain elastic rebound theory.

Question 43

Earth's core ____.

A)is solid
B)is liquid
C)has both liquid and solid components
D)is composed of minerals common at Earth's surface
E)is thought to be composed largely of sulfur

Question 44

Some geologists believe that we could reduce the threat of earthquakes by pumping liquids into locked segments of active faults. What is the theory behind this belief?

Question 45

Trenching across an active fault ____.

A)releases pressure along the fault
B)allows geologists to find evidence of previous earthquakes
C)allows structures to be built to stop faulting activity
D)diminishes the intensity of earthquakes
E)produces secondary faults that reduce pressure on the major fault

Question 46

The temperature increase with depth ____.

A)is called the Moho
B)is called the lithospheric inclination
C)only occurs on continental plates
D)rises more slowly beneath spreading ridges than elsewhere beneath the seafloor
E)rises faster beneath spreading ridges than elsewhere beneath the seafloor

Question 47

The Seattle, Washington area ____.

A)is very likely to have a large earthquake in the foreseeable future
B)is very unlikely to ever have a large earthquake
C)has frequent small earthquakes and so is very unlikely to have a large earthquake
D)has large earthquakes about once every century
E)has never had a large earthquake

Question 48

How do geologists define an earthquake?

Question 49

The lithosphere is made up of the ____.

A)the crust and upper mantle
B)the crust and outer core
C)the crust and the inner core
D)upper mantle and outer core
E)upper mantle and inner core

Question 50

Scientists use seismic tomography to ____.

A)develop a three-dimensional model of Earth's interior
B)determine the location of an earthquake's epicenter
C)predict the timing and intensity of a future earthquake
D)determine the depth of an earthquake
E)decrease the intensity of an impending earthquake

Question 51

Continental crust ____.

A)is much thinner under mountain ranges than it is in the adjacent areas
B)is much thicker than average beneath the Rift Valleys of Africa
C)is usually described as "granitic"
D)consists of gabbro and basalt
E)is thinner than oceanic crust

Question 52

Many things can be done to improve the safety of current structures and of new buildings. List three (3)with a brief explanation.

Question 53

The composition of the mantle is primarily ____.

A)peridotite
B)basalt
C)granite
D)iron
E)gabbro

Question 54

Explain two measures of an earthquake's strength that are commonly used by seismologists.

Question 55

Why do earthquakes of similar size often have such large differences in their destructiveness? Why are they so different in the number of people they kill?

Question 56

In contrast to continental crust, oceanic crust is ____.

A)granitic
B)less dense
C)thicker
D)complex
E)simpler

Question 57

Beneath some valleys in East Africa and in a large area called the Basin and Range Province in the western United States and northern Mexico, the crust ____.

A)appears to be in the initial stages of rifting
B)appears to have undergone numerous earthquakes in the last 1000 years
C)is much thicker than it is in the surrounding areas
D)is composed mostly of basalt
E)is composed of fragments of extinct volcanoes

Question 58

Discuss the geothermal gradient. What is it? What causes it? What are its limitations?