Chapter 10 Earthquakes

If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is steep (closer to vertical than horizontal). a. reverse b. thrust c. strike slip d. normal

Which earthquake intensity scale assesses the effects of an earthquake on humans and human-made structures? a. Mercalli scale b. Richter scale c. seismic-moment magnitude scale

The greatest earthquake ever recorded by seismographs occurred in 1960 in Chile and measured ____________ on the seismic-moment magnitude scale. a. 9.0 b. 10.0 c. 10.5 d. 9.5

Which of these areas of the United States would you expect to have the highest occurance of seismic activity? a. Southeast b. West c. Central d. Northeast

Faulting and earthquakes are examples of ____________. a. ductile behavior b. brittle behavior

Which earthquake severity scale measures the amplitude of deflection of a seismograph pen, standardized to an idealized distance of 100 km between epicenter and seismograph? a. Mercalli scale b. seismic-moment magnitude scale c. Richter scale

A primary force opposing motion on all faults is ____________. a. gravity b. Van der Waal's force c. magnetic attraction among iron-rich minerals d. friction

Body waves include ____________. a. both S- and P-waves b. P-waves only c. both L- and R-waves d. both surface and interior waves

Virtually all of the deaths attributed to major earthquakes have resulted from the collapse of buildings. a. false b. true

According to the moment magnitude scale (Mw)—a magnitude 8 earthquake would be 1,000 times greater than a magnitude ____________ earthquake. a. 9 b. 4 c. 5 d. 7

Which earthquake severity scale varies from locality to locality for a single earthquake? a. Richter scale b. seismic-moment magnitude scale c. Mercalli scale

The intersection between a fault plane and the ground surface is called the ____________. a. plunge b. seismic interface c. fault trace d. dip line

Which earthquake severity scale takes vibration caused only by the S-waves into account when estimating the size of an earthquake? a. seismic-moment magnitude scale b. Mercalli scale c. Richter scale

What geological setting(s) would you expect to produce seismic activity? a. Rift valley b. Basin c. Collisional mountain belt d. All of the above are correct

Medium- and deep-focus earthquakes occur along ____________. a. convergent-plate boundaries only b. divergent-plate boundaries only c. transform-plate boundaries only d. All of the above are correct.

On December 26, 2004, a magnitude 9 earthquake generated a tsunami that devastated coastlines on the ____________. a. Atlantic Ocean b. Indian Ocean c. Arctic Ocean d. Pacific Ocean

The quantity of offset that occurs along a fault is termed ____________. a. the fault gauge b. displacement c. accumulation d. fault gouge

Long-term prediction of earthquake behavior ____________. a. is based on past earthquake activity b. works on the principle that zones of past seismicity will be active in the future c. includes the notion of seismic gaps—places where an earthquake is "overdue" d. All of the above are correct.

All discovered faults are likely to experience earthquakes in the next few hundred years. a. false b. true

A surface along which rock on opposed sides is offset by earthquake-induced slip is called a ____________. a. joint b. fold c. wall d. fault

Earthquakes that occur in a band called a ____________ can be used to track the motion of subducted oceanic lithosphere. a. Wegener belt b. seismic gap c. Wadati-Benioff zone

How can damage and injury be minimized in areas prone to seismic activity? a. earthquake zoning b. engineering controls c. warning systems d. All of the above are correct

Earthquake waves that pass through the interior of Earth are termed ____________. a. body waves b. interior waves c. R-waves d. surface waves

A coiled spring would be useful in illustrating a ____________ wave. a. surface b. compressional c. shear d. body

An earthquake occurs with an epicenter in the town of New Madrid, Missouri, in the interior of the North American Plate. Where might the hypocenter of this earthquake plausibly be found? a. 20 km beneath New Madrid b. 10 km south of New Madrid c. in New Madrid ("hypocenter" and "epicenter" mean precisely the same thing) d. 200 km beneath New Madrid

If a fault is nearly vertical in orientation and the two walls of rock on opposite sides slide past one another horizontally, the fault is termed ____________. a. thrust b. normal c. strike slip d. reverse

Which type of fault does NOT, by definition, have a fault trace? a. normal fault b. reverse fault c. blind fault d. None of the above are correct; all faults have recognizable traces

Seismic retrofitting is the process of __________. a. strengthening existing buildings and structures b. mapping areas prone to earthquakes c. predicting earthquakes d. releasing energy

At any point along the surface of an oblique (nonvertical) fault, the ____________. a. footwall lies to the left of the hanging wall b. hanging wall lies to the left of the footwall c. footwall lies vertically above the hanging wall d. hanging wall lies vertically above the footwall

How many seismic stations are necessary to find the epicenter of an earthquake? a. one b. four c. three d. two

Aftershocks following a major earthquake ____________. a. may continue for days after the initial earthquake b. are mostly much smaller than the original earthquake c. may occur on the same fault as the original earthquake, or a different fault d. All of the above are correct

Vertical motion seismographs record earthquakes through the production of a squiggly diagram called a ____________. a. wave sheet b. seismogram c. camera lucida d. pictogram

Which earthquake severity scale takes into account the type of rock that has been fractured? Select one: a. seismic-moment magnitude scale b. Mercalli scale c. Richter scale

Which type of earthquake has the highest velocity? a. L-wave b. R-wave c. P-wave d. S-wave

The point within Earth where an earthquake takes place is termed the ____________. a. epicenter b. vertex c. eye of the fault d. hypocenter (focus)

Generally, which type of earthquake waves travel fastest? a. body waves b. interior waves c. R-waves d. surface waves

Faults that have moved recently or are likely to move in the future are referred to as ____________. a. active b. reverse c. normal d. passive

Earthquakes are likely to occur along ____________. a. transform-plate boundaries only b. divergent-plate boundaries only c. All of the above are correct. d. convergent-plate boundaries only

If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is shallow (much closer to horizontal than vertical). a. normal b. reverse c. thrust d. strike slip

A tsunami is ____________. a. an earthquake-generated sea wave that can sometimes destroy coastal cities thousands of kilometers from its source b. a sloshing of water back and forth within a lake or bay c. the tendency of wet, clay-rich soils to behave like a liquid during an earthquake d. the amount of change in elevation of local sea level caused by a surging wave

Surface waves ____________. a. are the first waves to arrive at a seismograph station after an earthquake b. produce most of the damage to buildings during earthquakes c. travel more rapidly than body waves d. are the first waves initially produced in an earthquake

All else being equal, an earthquake that strikes in the eastern United States would produce shaking that would be felt ____________ than one that occurred in the western United States. a. over a lesser distance b. over the same distance c. over a greater distance

The point on Earth's surface directly above the point where an earthquake occurs is termed the ____________. a. epicenter b. eye of the fault c. hypocenter (focus) d. vertex

Periods of intermittent sliding on a fault as a result of the release of stress during episodes of displacement, followed by stress buildup to the point that the fault is reactivated is termed ____________. a. stick-slip behavior b. chaotic faulting c. reverse faulting d. thrust faulting

Sandy substrate is susceptible to ____________ during an earthquake. a. liquifaction b. displacement c. collapse d. faulting

Movement on a fault may occur without generating earthquakes. a. false b. true

Earthquakes are a result of ____________. a. mantle upwelling b. a sudden change in atmospheric pressure c. lithosphere-plate movement d. erosion

Short-term predictions of earthquake behavior ____________. a. are primarily based on the behavior patterns of farm animals b. have been largely unreliable c. are correct approximately 50% of the time d. have saved millions of lives in the past decade alone

If, during an earthquake, a footwall slides upward relative to a hanging wall, the fault is termed ____________. a. reverse b. normal c. thrust d. strike slip

Geologists who specifically study earthquakes are called ____________. a. speleologists b. paleontologists c. vulcanologists d. seismologists