Chapter 10 (GEOL107)

Sand volcanoes and sand blows are surface expressions of... A. landslides. B. tsunamis. C. liquefaction. D. fault displacement. E. firestorms.

C. liquefaction.

Identify the true statement. Choose one: A. Seismic waves become smaller in amplitude with increasing distance from the epicenter. B. Earthquake intensity is based on ground motion recorded by a seismograph; magnitude is based on the amount of damage produced. C. Contour lines representing Richter values are used to delimit zones of earthquake intensity; the greater the quake, the higher the intensity values and the wider the zones. D. Earthquakes never have hypocenters (foci) deeper than about 100 km (60 miles).

A. Seismic waves become smaller in amplitude with increasing distance from the epicenter.

Long-term earthquake predictions Choose one: A. are based on the recurrence interval and the identification of seismic zones. B. are based on the study of earthquake swarms. C. involve looking for changes in emissions of gases such as helium and/or radon. D. are unreliable and do not provide useful information.

A. are based on the recurrence interval and the identification of seismic zones.

The Richter scale Choose one: A. is today termed a local magnitude (ML) reading. B. measures the amplitude of the largest P-wave deflection on a seismogram. C. works well for very large earthquakes. D. measures the size of an earthquake in terms of the damage it does (its intensity).

A. is today termed a local magnitude (ML) reading.

A tsunami Choose one: A. may be just a broad, gentle swelling out at sea but grows as it approaches the shore. B. is a special kind of tidal wave caused by the gravitational attraction of the Sun, not the Moon. C. can get big, but never bigger than 30 feet high. D. is dangerous near its source but dies out within about 200 miles.

A. may be just a broad, gentle swelling out at sea but grows as it approaches the shore.

Identify the true statement. Choose one: A. Low-frequency waves lose energy more rapidly than do high-frequency waves. B. In the 1985 Mexico City earthquake, high-frequency waves weakened with distance, but unconsolidated sediments beneath the city amplified low-frequency waves. C. The variety of different wave frequencies (the frequency content) of an earthquake remains the same with distance from the hypocenter. D. Resonance occurs when waves of different frequency interfere, causing a decrease in seismic energy.

B. In the 1985 Mexico City earthquake, high-frequency waves weakened with distance, but unconsolidated sediments beneath the city amplified low-frequency waves.

Seismometers Choose one: A. measure vertical (up-and-down) ground motion but cannot measure horizontal (back-and-forth) motion. B. can "feel" (or record) large earthquakes that happen on the opposite side of the world. C. begin recording when the ground shakes and surface waves arrive. D. are only sensitive enough to record ground movements down to about 1 mm.

B. can "feel" (or record) large earthquakes that happen on the opposite side of the world.

Which term describes the current theory of earthquake formation? Choose one: A. InSAR B. elastic rebound C. foreshocks D. aftershocks

B. elastic rebound

Which of the following earthquake phenomena is the LEAST likely to actually injure or kill humans? Choose one: A. landslides and avalanches B. ground shaking C. sediment liquefaction D. tsunami

B. ground shaking

The average time between successive earthquake events along a given fault is called a... A. recurrence interval. B. seismic gap. C. seismic zone. D. S-P time. E. moment magnitude.

B. seismic gap.

The tsunami event of December 26, 2004, Choose one: A. could have resulted in an even greater death toll, but for the timely warnings issued immediately after the earthquake. B. was first noticed as a withdrawal of the sea along the beach front. C. consisted of only local, near-field tsunamis that affected the island of Sumatra. D. involved a magnitude 5.3 earthquake that lasted only 2 minutes.

B. was first noticed as a withdrawal of the sea along the beach front.

Examining sedimentary bedding in a geologic study reveals that disrupted layers formed 260, 820, 1,200, 2,100, and 2,300 years ago. What is the recurrence interval of the earthquakes that caused the disruption? Choose one: A. 200 years B. 560 years C. 510 years D. 380 years

C. 510 years

Identify the true statement. Choose one: A. The ML earthquake magnitude scale (Richter) can accurately define extremely large earthquakes. B. Thrust faults result from stretching the Earth's crust; normal faults, from squeezing and shortening it. C. All earthquake magnitude scales are logarithmic, which means that a difference of one unit in magnitude reading represents a 10-fold difference in ground motion. D. Local magnitude (ML) rating is the number now used for the official (archival) record.

C. All earthquake magnitude scales are logarithmic, which means that a difference of one unit in magnitude reading represents a 10-fold difference in ground motion.

Identify the true statement. Choose one: A. Shallow-focus quakes do less damage than deep-focus quakes. B. S-waves are compressional body waves; P-waves are shear body waves. C. R- and L-waves are surface seismic waves. D. Surface waves are the first to show up on a seismogram recording of a quake.

C. R- and L-waves are surface seismic waves.

Identify the statement that is true about the 2010 Haiti earthquake. Choose one: A. Faulting occurred along a divergent-plate boundary between the Caribbean and North American plates. B. The earthquake generated a tsunami that was responsible for the majority of the lives lost. C. The likelihood of an earthquake was great because stress had been building on the fault for over 200 years. D. Shaking was amplified as waves passed from weak sediments into harder bedrock.

C. The likelihood of an earthquake was great because stress had been building on the fault for over 200 years.

Fault creep Choose one: A. may happen because fault planes coated in clay often create amplified shock waves. B. is likely to occur in regions where rock is strong and brittle. C. is movement along a fault without an accompanying earthquake. D. quickly releases built-up stress in short bursts.

C. is movement along a fault without an accompanying earthquake.

Earthquake prediction is not highly reliable, but geologists do know that Choose one: A. recurrence intervals can provide accurate short-term predictions. B. earthquakes will never happen in seismic gaps. C. more earthquakes happen along plate boundaries than at intraplate locations. D. foreshocks always precede large, devastating earthquakes.

C. more earthquakes happen along plate boundaries than at intraplate locations.

Earthquakes in California are Choose one: A. always above magnitude 7.5, because the San Andreas is such a large fault. B. the result of reverse faulting along the San Andreas fault. C. shallow and occur in the upper 15 to 20 km of crust, even though the San Andreas fault cuts through the crust to deeper depths. D. the result of widening along the San Andreas fault, which will eventually cause western California to sink into the ocean.

C. shallow and occur in the upper 15 to 20 km of crust, even though the San Andreas fault cuts through the crust to deeper depths.

What is one of the differences between body waves and surface waves? Choose one: A. Surface waves are described as compressional or tensional. B. Surface waves travel much more quickly than body waves. C. Body waves are usually far more destructive. D. Body waves are described as compressional or shear.

D. Body waves are described as compressional or shear.

Which of the following statements is true? Choose one: A. S-waves travel twice as fast as P-waves. B. P, S, L, and R are all body waves that pass through the Earth's interior. C. The hypocenter (focus) is the point on the Earth's surface directly above the epicenter. D. Governments support the worldwide seismic network because it can detect nuclear bomb tests.

D. Governments support the worldwide seismic network because it can detect nuclear bomb tests.

Identify the statement that is true about tsunami events. Choose one: A. The velocity of a tsunami wave increases when the wave moves from open ocean into shallower water. B. Tsunami waves that affect the local area around an earthquake's epicenter are called far-field tsunamis. C. The wavelengths of tsunami waves are often shorter than those for wind-driven waves. D. Tsunamis may be generated by underwater earthquakes, eruptions of island volcanoes, or submarine landslides.

D. Tsunamis may be generated by underwater earthquakes, eruptions of island volcanoes, or submarine landslides.

A Wadati-Benioff zone is Choose one: A. a series of strike-slip faults along a transform boundary. B. an area in a divergent boundary where new lithosphere forms. C. an area where continents collide following the subduction of the lithosphere. D. a band of earthquakes along subducting lithosphere in a convergent boundary.

D. a band of earthquakes along subducting lithosphere in a convergent boundary.

The locations of major earthquakes and volcanic eruptions Choose one: A. are usually toward the centers of tectonic plates. B. always mark places where plates are converging, never where they're diverging. C. are not similar to each other. D. are usually along plate boundaries.

D. are usually along plate boundaries.

Liquefaction Choose one: A. is the sudden increase in strength of some soils that happens because of earthquake shaking. B. does not affect clay-rich sediment, because clays stick together by cohesion. C. caused the greatest amount of damage in the San Francisco earthquake of 1908. D. can cause wet, silty or sandy sediment to turn into an unstable slurry.

D. can cause wet, silty or sandy sediment to turn into an unstable slurry.

What kind of fault is least likely to produce a tsunami? A. normal fault B. reverse fault C. thrust fault D. strike-slip fault

D. strike-slip fault

Which of the following is a good technique for building earthquake-resistant structures? Choose one: A. using tile roofing rather than sheet metal B. making buildings wider at the top than at the base C. using concrete-block rather than wood-frame construction D. wrapping bridge supports with steel cables

D. wrapping bridge supports with steel cables