Deck 5: Earthquakes Throughout the United States and Canada

Question 1

The large left step in the San Andreas fault in the Los Angeles area causes compressive ruptures along east-west-oriented ________ faults as in the 1971 San Fernando and 1994 Northridge events.

A)normal
B)thrust
C)strike-slip
D)transform

Answer 1

B

Question 2

In the 1989 Loma Prieta quake,the Marina District building collapses were extensive,and numerous destructive fires broke out,due to all but which one of the following?

A)amplified shaking
B)deformation and liquefaction of artificial-fill foundations
C)soft first-story construction that led to building collapses
D)widespread looting and arson

Answer 2

D

Question 3

Today,North America has several small- to medium-sized plates subducting beneath its ____________.

A)eastern margin
B)western margin
C)northern margin
D)southeastern margin
E)margins,all around the North American plate

Answer 3

B

Question 4

How does a locked zone of a large strike-slip fault catch up with a creep zone?

A)by frequent earthquakes around magnitude 4
B)by infrequent and large creep events
C)by frequent and large creep events
D)by frequent but small earthquakes
E)by infrequent but large fault movements (i.e. ,large quakes)

Question 5

In San Francisco's Marina district in 1989,some fill underwent permanent deformation and settling,and some formed slurries as underground water and loose sediment flowed like a fluid in a process known as ______________.

A)solifluction
B)creep
C)liquefaction
D)plasticity
E)asthenocity

Question 6

Another class of active faults is created by southern California pushing into the "Big Bend" of the San Andreas fault.These faults are __________________.

A)mostly east-west-oriented normal faults
B)mostly north-south-oriented thrust faults (reverse faults)
C)mostly east-west-oriented thrust faults (reverse faults)
D)mostly north-south-oriented normal faults

Question 7

Constraining bends in large strike-slip faults commonly "lock up";thus,movements there tend to be _________________.

A)infrequent and large
B)frequent and small
C)infrequent and small
D)tensional and mostly vertical
E)infrequent and large and frequent and small are correct

Question 8

In 1985 in Mexico City,building damages were the greatest and the number of deaths the highest where all but which one of these factors combined and created resonance:

A)The earthquakes sent a tremendous amount of energy in seismic waves in the 1- to 2-second frequency band.
B)The areas underlain by thick,soft clays vibrating at 1- to 2-second frequencies amplified the seismic waves.
C)Single-story buildings with a 1-second resonant period vibrated themselves to pieces.
D)Buildings of 6 to 16 stories vibrated in the 1- to 2-second frequency band.

Question 9

The San Andreas fault's earthquakes in historic time include which of the following?

A)a magnitude 8+ caused by a 225-mi-long rupture in central California in 1857
B)a magnitude 8+ due to a 265-mi-long rupture passing through the San Francisco Bay region in 1906
C)a magnitude 7.1 unleashed by a 25-mi-long rupture near Santa Cruz in 1989
D)All of these are correct.

Question 10

Organic material in sediment layers can be dated by measuring the amount of radioactive ________ present.

A)oxygen
B)hydrogen
C)uranium
D)carbon
E)thorium

Question 11

In the last 5.5 million years,rifting action has torn Baja California and California west of the San Andreas fault (including San Diego,Los Angeles,and Santa Cruz)from the ______________.

A)Pacific plate and piggybacked them onto the Juan de Fuca plate
B)Pacific plate and piggybacked them onto the North American plate
C)North American plate and piggybacked them onto the Juan de Fuca plate
D)North American plate and piggybacked them onto the Pacific plate
E)Nazca Plate and piggybacked them onto the Cocos plate

Question 12

We know that the part of California on the Pacific plate will not break off in a giant earthquake and sink into the Pacific Ocean because ______________________.

A)the Pacific plate is being subducted beneath California instead
B)the San Andreas fault is a thrust fault,not a normal fault
C)of isostasy
D)convective forces
E)oceanic circulation

Question 13

Much of the San Francisco Marina District is built on artificial fill debris from the buildings ruined by the 1906 earthquake.Seismic waves in 1989 were ____________ in this artificial fill.

A)damped (i.e. ,decreased or attenuated)
B)amplified
C)not noticeably affected

Question 14

The largest earthquakes along western North America are due to subduction beneath the continent.They include ________________.

A)the magnitude 9.2 Alaska earthquake in 1964 which was due to subduction of the Pacific plate
B)the magnitude 8.1 Mexico City event in 1985 which was caused by subduction of the Cocos plate
C)the plates subducting beneath Oregon and Washington which generated a magnitude 9 earthquake on 26 January 1700
D)All of these are correct.

Question 15

In 1985,as a result of the Michoacan earthquake many buildings collapsed and killed about 8000 people in Mexico City,even though the city lies 350 miles from the epicenter.This was caused by all but which of the following?

A)resonance between seismic waves
B)soft lake-sediment foundations
C)improperly designed buildings
D)collapse of thousands of single-story frame houses

Question 16

The spreading-center segment at the southern end of California's Salton Sea is marked by all but which of the following?

A)glassy volcanic domes
B)high heat flow
C)boiling mud pots
D)major geothermal energy reservoirs
E)a lack of small earthquakes because magma is too close to the Earth's surface

Question 17

When is the best time for an earthquake to occur in California to minimize loss of life?

A)during rush hour when people are not in buildings
B)during the night,when most people are home and asleep
C)in the middle of the day when people are in school or working
D)it does not matter what time of day it occurs

Question 18

Recent work has shown that the last major earthquake in the Cascadia subduction zone occurred about 9 p.m.on 26 January 1700 and was about magnitude 9.This is known by __________________.

A)analysis of annual growth rings in trees of downed forests along the Oregon-Washington-British Columbia coast showing large rings after 1699
B)Tsunami of 2-m (7-ft)height that hit Japan from midnight to dawn pointing to a 9 p.m.earthquake along the Washington-Oregon coast on 8 December 1699
C)Jesuit missionaries in the Chile and Alaska areas recording a very large quake and accompanying tsunami in their daily logs
D)Tsunami gauge measurements at the Pacific Tsunami Center
E)analysis of annual growth rings in trees of downed forests along the Oregon-Washington-British Columbia coast showing no rings after 1699 and Tsunami of 2-m (7-ft)height that hit Japan from midnight to dawn pointing to a 9 p.m.earthquake along the Washington-Oregon coast on 26 January 1700 are correct

Question 19

Prehistoric earthquakes may be interpreted using faulted pond sediments.The amount of offset of sediment layers from one earthquake is proportional to the ________________.

A)amount of time since the last major earthquake
B)amount of radioactive material in the sediment
C)earthquake magnitude
D)isostatic anomaly

Question 20

When the part of California west of the San Andreas fault plows into Alaska it _______________.

A)will become subducted beneath Alaska's southern margin
B)will become part of Alaska's southern margin
C)will turn into a spreading ridge,changing the direction of movement of the Pacific plate
D)will turn and head westward along Alaska's southern margin

Question 21

Several recent earthquakes in Washington's Puget Sound region were caused by movement of the subducting ______________ plate.

A)Pacific
B)North American
C)Cocos
D)Juan de Fuca
E)Nazca

Question 22

If Alaska and California are ignored,the list of 10 largest U.S.earthquakes shows ____________.

A)only events centered in Washington and Oregon
B)only events centered in Washington,Montana,and Hawaii
C)only events centered in Washington,Oregon,Hawaii,and Nevada
D)8 events centered in western states and 2 events centered in Missouri
E)10 events affecting at least 10 different states

Question 23

The New Madrid earthquakes are apparently related to ______________.

A)an old buried transform fault
B)an old buried rift zone
C)an old buried subduction zone
D)an old buried hazardous waste dump
E)an old buried plume

Question 24

Paleoseismologic analysis of trenches cut across faults and folds in the New Madrid,Missouri,area has led the U.S.Geological Survey to forecast a 90% chance of a magnitude ______ earthquake here within the next 50 years.

A)4 to 5
B)6 to 7
C)8 to 9
D)9+

Question 25

The dominant type of faulting in the Great Basin region is ______________.

A)normal faulting
B)reverse faulting
C)strike slip faulting
D)thrust faulting
E)transform faulting

Question 26

On 9 January 1857,the San Andreas fault segment between Cholame and San Bernardino broke loose at its northwestern end,and the rupture propagated southeastward in the great ________ earthquake with a magnitude of about 8.3.

A)San Francisco
B)Loma Prieta
C)Owens Valley
D)Fort Tejon
E)Hebgen Lake

Question 27

The state (other than Alaska)most likely to have a magnitude 9 or larger earthquake in the next several hundred years is ______________.

A)California
B)Washington
C)Missouri
D)Nevada
E)South Carolina

Question 28

The crustal thickness in the Great Basin is ____________________.

A)thicker than Mid-continental North American crust
B)thinner than Mid-continental North American crust
C)thinner than oceanic crust and thinner than Mid-continental North American crust are correct
D)thicker than oceanic crust and thinner than Mid-continental North American crust are correct
E)thicker than oceanic crust and thicker than Mid-continental North American crust are correct

Question 29

Which state accounts for the greatest percentage of all U.S.earthquakes of magnitude 3.5 and above?

A)California
B)Hawaii
C)Alaska
D)Washington
E)Nevada

Question 30

Which of the following represents evidence for major fault movement on the Seattle fault zone about 1100 years ago?

A)The former shoreline at Restoration Point was uplifted 23 feet above the high-tide line in a single event.
B)Numerous large landslides occurred at this time,including some that carried trees in growth position to the bottom of Lake Washington.
C)Several tsunami deposits have been recognized in the sediment layers of the area.
D)The same date appears in the ages of six major rock avalanches in the Olympic Mountains.
E)All of these are correct.

Question 31

The Great Basin region between the eastern Sierra Nevada in California and the Wasatch Mountains in Utah ______________________ in response to plate tectonic forces.

A)has been compressed in an east-west direction
B)has expanded in an east-west direction
C)has been compressed in a north-south direction
D)has expanded in a north-south direction
E)is now a subduction zone

Question 32

Which of the following states has the highest earthquake risk?

A)Michigan
B)Nebraska
C)Arkansas
D)North Dakota
E)Florida

Question 33

On 3 November 2002,a large earthquake occurred in __________.Because of its similarity to the 1857 Fort Tejon earthquake on the San Andreas fault,this event has been compared to the much-anticipated "Big One" in Southern California.

A)Oregon
B)Mexico
C)Alaska
D)Canada
E)Nevada

Question 34

Which of the following states has the lowest earthquake risk?

A)Arkansas
B)Massachusetts
C)South Carolina
D)Nevada
E)Florida

Question 35

The 17 January 1994 Northridge earthquake in Los Angeles was generated on a _______ thrust fault.

A)slow
B)elliptical
C)upside down
D)trap-door
E)blind

Question 36

California accounts for _______ of all U.S.earthquakes of magnitude 3.5 and above.

A)82%
B)64%
C)57%
D)23%
E)17%

Question 37

At Hebgen Lake in 1959 an earthquake larger than magnitude 7 greatly affected ____________.

A)Yellowstone National Park
B)Olympia National Park
C)Denali National Park
D)Yosemite National Park
E)Grand Canyon National Park

Question 38

Which four states account for 91% of all U.S.earthquakes of magnitude 3.5 and above?

A)California,Alaska,Washington,Oregon
B)California,Alaska,Washington,Hawaii
C)California,Alaska,Hawaii,Nevada
D)California,Hawaii,Washington,Nevada
E)California,Hawaii,Nevada,Idaho

Question 39

The ________ segment of the San Andreas fault is the only one not to have a long rupture in historic time.In prehistory,it has ruptured every 250 years on average,but the last big movement was in 1680.

A)Coachella Valley
B)Loma Prieta
C)Cholame to San Bernardino
D)Landers

Question 40

When compared to California,seismic energy in the eastern U.S.is ______________.

A)transmitted more effectively in the older,more solid rocks
B)transmitted less effectively in the older,more solid rocks
C)transmitted more effectively in the younger,more solid rocks
D)transmitted less effectively in the younger,more solid rocks
E)transmitted less effectively because the earthquakes are smaller

Question 41

The fires from the 1906 San Francisco earthquake did about ten times as much damage as the earthquake itself.

Question 42

The Charleston,South Carolina,earthquake of 1886 occurred along a seismic belt that may be related to _________________.

A)tectonic stresses transmitted across the North American continent from California
B)an ancient subduction zone beneath the Appalachian Mountains
C)an adjacent oceanic fracture zone on the Atlantic seafloor
D)canal building prior to the Civil War
E)remnants of the African plate attached to North America

Question 43

Major southern California faults,such as the Imperial,San Jacinto system,Cerro Prieto,Elsinore,and Laguna Salada,also appear to be part of the San Andreas plate boundary fault system carrying peninsular California to the northwest.

Question 44

The southernmost segment of the San Andreas fault,from San Bernardino to the Salton Sea,is a complex zone that has generated several truly large earthquakes in historic times,but it has no locked zones within it.

Question 45

The creeping movements along some segments of the San Andreas fault are shown by millimeters per year of offset of sidewalks,fences,buildings,and other features.

Question 46

The Imperial Valley is the only part of the United States that sits on an actively closing ocean floor.

Question 47

Recent work has shown that the last major earthquake in the Cascadia subduction zone occurred about 9 p.m.on 26 January 1700 and was about magnitude 9.

Question 48

When magma is on the move at shallow depths _______________.

A)it does so quietly without generating earthquakes
B)it commonly generates a swarm of small earthquakes referred to as delirium tremens
C)it commonly generates a swarm of large earthquakes referred to as delirium tremens
D)it commonly generates a swarm of small earthquakes referred to as harmonic tremors
E)it commonly generates a swarm of large earthquakes referred to as harmonic tremors

Question 49

The San Andreas fault has different behaviors along its length.

Question 50

Earthquakes in Hawaii are mostly related to ________________.

A)subduction along the Pacific plate margin
B)strike-slip faulting along the Hawaiian Islands transform fault
C)lava flows erupting from the volcanic craters
D)movement of volcanic magma beneath the ground
E)the Emperor seamounts colliding

Question 51

The duration of strong ground shaking in the 1964 Alaskan Good Friday earthquake was 3 to 4 minutes.

Question 52

The "creeping" section of the San Andreas fault between San Juan Bautista and Cholame has numerous earthquakes smaller than magnitude 6 that accommodate the plate-tectonic forces before they build to high levels.

Question 53

In the San Francisco Bay Area,during the nineteenth century,earthquakes with magnitudes greater than 6 were much less common than in the 20^th century.

Question 54

Common reasons for building failure in the World Series quake included poor connections of houses to their foundations,buildings made of un-reinforced masonry or brick-facade construction,and two- to-five-story buildings deficient in shear-bearing internal walls and supports.

Question 55

When rock heats and liquefies into a magma its volume _____________.

A)expands,and neighboring brittle rock must fracture and move out of the way
B)decreases and neighboring brittle rock collapses to make up for the loss of volume
C)does not change
D)decreases due to sublimation

Question 56

The Cascadia subduction zone is 750 miles long,and its characteristics of youthful oceanic plate and strong coupling with the overriding plate are similar to situations in southwestern Japan and southern Chile where very large earthquakes have occurred.

Question 57

The biggest earthquake ever recorded instrumentally occurred on 22 May 1960 in southern Chile with a seismic moment magnitude of 9.5.

Question 58

The duration of shaking in 1985 in Mexico City was decreased due to seismic energy being trapped within the soft sediments.

Question 59

Today,the San Francisco section of the San Andreas fault has an excessive number of earthquakes relative to other parts of the San Andreas fault.

Question 60

The 1985 Mexico City earthquake was caused by eastward subduction of a small plate,the Cocos plate,beneath the North American plate.Other small plates are subducting beneath North America at the Cascadia subduction zone.

Question 61

Most of the 131 fatalities from the Good Friday earthquake in Alaska in 1964 were due to fire caused by rupturing of gas lines.

Question 62

Much of Utah's population lives within sight of the scarps of the 230-mile-long Wasatch Front,the zone of reverse and strike-slip faults separating the mountains from the Great Basin.

Question 63

In historic time,Nevada has averaged one earthquake with a magnitude in the 6s per decade and one with a magnitude in the 7s every 27 years.

Question 64

On 28 October 1983,the Lost River fault broke free for a magnitude 7.3 MS event,moving Borah Peak,Idaho's highest point,0.3 m (1 foot)lower.

Question 65

Adjustments related to plate-tectonic activity cause earthquakes from Washington to New Mexico,from Montana to California,and at other points throughout the West.

Question 66

In the last 30 million years,the region between the eastern Sierra Nevada in California and the Wasatch Mountain front in central Utah has contracted in an east-west direction,so Nevada is now half of its former width.

Question 67

The New Madrid,Missouri,1811-1812 earthquakes have never been equaled in the history of the United States for the number of closely spaced,large seisms and for the size of the felt area.

Question 68

Earthquake epicenters east of the Rocky Mountains are in random locations and do not cluster in certain areas.

Question 69

The subducting Juan de Fuca plate is only 10- to 15-million-years old and is warm and buoyant enough to couple with the North American plate as shown by strike-slip faults on the Juan de Fuca plate that also cut the overriding North American plate.

Question 70

As much as 20 percent of the relative motion between the Pacific and North American plates may be accommodated by the extensional stretching of the Basin and Range province,leaving numerous north-south-oriented mountain ranges separated by down-dropped,sediment-filled basins.

Question 71

The 1994 Northridge event was similar to the 1971 San Fernando earthquake in magnitude,number of people killed,and type of faulting.

Question 72

Ocean ridge spreading still occurs offshore of northernmost California,Oregon,Washington,and southern British Columbia,as well as in the Gulf of California.

Question 73

Because many of the thrust faults in the Los Angeles area do not reach the ground surface,their sound waves do not reach the surface with audible strength,so they are called deaf thrusts.

Question 74

In the last 6000 years,a magnitude 6.5 or stronger earthquake has occurred about once every 350 years on one of the Wasatch system faults,but no large earthquakes have been reported along the Wasatch Front faults since the arrival of Brigham Young in 1847.

Question 75

The Owens Valley quake of 1872 is estimated to have had a magnitude of 7.8 to 8,indicating that big earthquakes can and do happen far away from the coastal zone and the San Andreas fault.

Question 76

The zone of dangerous faults in Southern California is much wider than in the San Francisco Bay area,largely because the major plate-bounding fault (the San Andreas)is bent so far to the west that it makes it difficult for the Pacific plate to slide along on its northwestward journey.

Question 77

The Rio Grande rift in New Mexico,Colorado,westernmost Texas,and Mexico is one of the major continental rifts in the world where the continental crust is being heated and stretched from below.

Question 78

Nevada has several gaps in the belt of historic seismicity,suggesting residents in these seismic gaps may be in for some future earthquakes.

Question 79

Historic earthquakes in the Rio Grande rift area have had only small to moderate magnitudes,but the continental lithosphere continues to compress and shorten,thus presenting a real hazard for large earthquakes near settlements including Albuquerque,Socorro,and Las Cruces in New Mexico,El Paso in Texas,and Ciudad Juarez in Mexico.

Question 80

The bounding faults on the eastern side of the Great Basin are mostly down to the east,whereas the bounding faults on the western side (in eastern California and western Nevada)are down to the west.