ESCI 3

A hot spot track forms because:

Plates remain stationary while the mantle plume moves

A tectonic plate moves over a relatively stationary mantle plume

Mantle plumes move along plate boundaries

Volcanic arcs migrate due to subduction processes

B

In a typical hot spot track (e.g., Hawaiian Islands), how does the age of volcanoes change along the chain?

Youngest volcanoes are farthest from the hot spot

Youngest volcanoes are closest to the hot spot

All volcanoes are about the same age

Oldest volcanoes are closest to the hot spot

B

Which of the following statements concerning GPS is FALSE?

It is available for worldwide civilian use.

About 24 GPS satellites are orbiting Earth.

It is maintained by the United Nations Security Council.

It is an abbreviation for the Global Positioning System.

C

How fast are tectonic plates moving?

One hundredth of an inch per year

A few inches per year

A few feet per year

Tens of feet per year

B

Which of the following statements concerning different plate boundaries is FALSE?

Divergent plate boundaries are considered not hazardous as long as they are in the ocean basins.

Transform boundaries always form in ocean basins.

A convergent boundary where an oceanic plate sinks into the mantle is a subduction zone.

A convergent boundary between two continental plates is often a collision zone. 

B

Which of the following is NOT a divergent boundary.

Mid-Atlantic Ridge

East African Rift Valley

Mariana Trench

East Pacific Rise

C

Which of the following statements concerning rock deformation is FALSE?

Strain refers to force applied on rock.

Tensional stress causes stretching and compressional stress causes shortening.

Elastic deformation is reversible/recoverable.

Brittle failure of rocks is responsible for earthquake generation.

A

What is meant by elastic rebound in the context of earthquakes?

The permanent sinking of land after an earthquake

The gradual bending of rocks over millions of years

The movement of magma toward the surface

The sudden release of accumulated elastic strain, causing rocks to snap back to a less deformed state

D

Based on the right-hand rule, if the strike of a fault is north (0º), the fault dips in which direction? 

N

E

S

W

East

Which of the following statements concerning normal faults is FALSE?

The hanging wall drops relative to the footwall.

They occur under tensile stress.

Many faults in the Basin and Range are normal faults.

Convergent plate boundaries host mostly normal faults.

D

Which of the following statements concerning reverse faults is FALSE?

They occur under compressional stress.

Those with small dip angles (<20 degrees) are called thrust faults.

The San Andreas fault is a reverse fault.

Convergent plate boundaries host many reverse faults.

C

What is a left-lateral strike-slip fault?

a nearly vertical fracture where the block of crust on the opposite side moves to the left relative to the observer. It is a horizontal motion fault, often resulting from tectonic pressure

Stick-slip faults do not generate earthquakes.

False

An epicenter is where the fault first slips.

False

Which of the following statements concerning tectonic environments that host earthquakes is FALSE?

In subduction zones, earthquakes can occur along the plate boundary and in the overlying and subducting plates.

Megathrust earthquakes occur in the subducting tectonic plate.

Subduction zones tend to host the largest earthquakes.

Earthquakes also occur in continent-continent collision zones along convergent plate boundaries.

B

Which of the following earthquakes was the largest magnitude earthquake ever recorded by seismic instruments?

2004 Sumatra earthquake

2011 Japan earthquake

1960 Chile earthquake

1964 Alaska earthquake

C

Which of the following is a common characteristic of intraslab earthquakes?

They occur only at shallow depths (<10 km)

They can occur at intermediate to deep depths within the subducting slab

They are typically associated with volcanic eruptions

They only occur along the Earth’s surface

B

Blind faults refer to faults that do not extend to the surface.

True

The displacement along the San Andreas Fault is primarily vertical.

False

Why were the 1811 and 1812 New Madrid earthquakes felt as far away as Boston?

They occurred at a plate boundary

The earthquakes were shallow oceanic events

They triggered volcanic eruptions

Seismic waves travel efficiently through the older, colder continental crust

D

Which of the following statements concerning seismic waves is FALSE?

P waves can pass through liquids, but S-waves cannot.

Particle motion of P waves consists of alternating compression and dilation.

S waves travel faster than P waves.

Both P and S waves are body waves.

C

Which seismic wave type produces particle motion that is purely horizontal and perpendicular to the direction of propagation?

P wave

S wave

Love wave

Rayleigh wave

C

Which of the following statements concerning seismic waves is FALSE?

Love waves travel faster than Rayleigh waves.

The particle motion of Rayleigh waves is elliptical.

Both Love and Rayleigh waves travel along the surface of Earth.

The amplitude of both Love and Rayleigh waves increases with depth.

D

A simple seismometer consists of a mass loosely coupled to the ground. When seismic waves pass, the ground moves but the mass tends to remain nearly stationary due to inertia. What does the instrument actually record?

The weight of the mass

The motion of the ground relative to the mass

The gravitational force acting on the mass

The velocity of seismic waves through the Earth

B

A seismic station records a P–S arrival time difference of 40 seconds. Another station records a difference of 20 seconds. Which station is farther from the earthquake?

The station with 20 seconds

The station with 40 seconds

Both are equally distant

Cannot be determined

B

Which of the following statements concerning earthquake magnitude scales based on the peak amplitude of a particular wave is FALSE?

Magnitude scales based on amplitudes tend to overestimate the magnitude of large earthquakes.

Different scales can give different magnitudes for the same earthquake.

The Richter magnitude scale is based on the maximum amplitude of all seismic waves recorded for a given event.

The body-wave magnitude scale is based on the maximum amplitude of P waves.

A

Compared to the ground displacement (amplitude) of a magnitude 4 earthquake, that of a magnitude 6 earthquake is

2 times greater

20 times greater

100  times greater

200 times greater

C

The maximum size (magnitude) of an earthquake is

unlimited because it depends on seismic moment

unknown because of a relatively short history (about 120 years) of earthquake monitoring

about magnitude 10, being limited by the size of the planet

about magnitude 12 based on extensive studies of megathrust earthquakes in subduction zones 

C

One unit increase in seismic moment magnitude is equivalent to an increase in seismic energy by

1

2

10

32

D

Which of the following statements concerning earthquake intensity is FALSE?

The scale used to measure earthquake intensity is called the Mercalli Scale.

The earthquake intensity scale reflects the size of the earthquake.

For earthquakes of similar sizes, those that occur in the eastern U.S. tend to cause damage over a larger area than those occur in the western U.S.

Earthquake intensity depends on the distance to the hypocenter.

B

Reinforced buildings tend to suffer greater damage than unreinforced buildings during an earthquake.

False

Which type of ground would experience the largest intensities during an earthquake?

Granite bedrock  

Sandstone bedrock

Soft sediments

Intensities are independent of the type of ground

C

Earthquakes can cause lateral spreading of Earth’s crust along faults, leaving deep gaps in the crust.

False

Which of the following statements concerning the effect of seismic waves on buildings is FALSE?

P waves usually cause very little damage.

Shearing motion caused by S waves tends to cause significant damage.

Up and down motion caused by Love waves tends to cause the most significant damage.

Surface waves tend to produce larger ground shaking than body waves.

C

Which of the following building designs is ineffective in reducing the possibility of earthquake’s damage to a building?

Diagonal bracing

Ground-floor garages

Base isolation

Tuned mass dampers

B

When the ground shaking occurs at higher frequencies than the natural vibration frequencies of buildings, the buildings oscillate at larger amplitudes.

False

Foreshocks always occur prior to a mainshock and are therefore useful for earthquake prediction.

False

Which of the following statements concerning earthquake prediction and forecasting is FALSE?

Forecast is a statement of probability and requires many observations to be validated.

Validation of a prediction requires a single observation.

Announcing earthquake forecasts tends to cause more hysterical public reaction than announcing predictions.

Announcing earthquake forecast encounters less accountability issues than announcing predictions.

C

Which of the following statements concerning the most recent megathrust earthquake in the Cascadia subduction zone is FALSE?

It generated a large tsunami that traveled across the Pacific Ocean.

It caused subsidence of the coastal area.

An earthquake of this magnitude occurs about every 100 years on average in Cascadia.

It resulted in formation of turbidites

C

Current earthquake early warning systems are based on which of the following concepts?

The detection of foreshocks before the main earthquake

The detection of P waves that arrive before stronger S and surface waves

The detection of a sudden change in ground motion using GPS

The detection of a sudden drop in P wave velocity

B

Which factor most directly determines the initial amplitude of a tsunami generated by an earthquake in the open ocean?

Volume of water displaced

Water depth above the earthquake rupture

Earthquake magnitude

Vertical fault displacement

D

On average, 100-m-high waves are generated by a megathrust earthquake every 20 years in the Pacific.

False

Volcanoes on Canary Islands can pose a significant tsunami threat to the Atlantic coast because large tsunami of several hundred meters high can be generated by

submarine explosions

pyroclastic flow caused by volcanic eruption

flank collapse

earthquakes

C

The average wavelength of tsunami waves is  

360 m

3.6 km

36 km

360 km

D

Tsunami waves do not “feel the bottom” in the open ocean.

False

How does tsunami wave speed change as it approaches the shore?

It decreases because water depth becomes shallower

It increases because wave energy is concentrated

It remains constant regardless of depth

It first increases and then decreases near the shore

A

The depth or height of flood/tsunami water measured from the ground at a given location is

Run-up height

Tsunami amplitude

Inundation depth

Ground height

C

The first tsunami wave that arrives to the shore tends to be the largest.

False

Which of the following measures would be least effective in reducing tsunami damage?

Orienting buildings parallel to the shoreline

Planting well-rooted vegetation

Constructing reinforced concrete walls

Elevating buildings on open foundations

A

Which of the following statements concerning tsunami-warning systems is FALSE?

Tsunami is detected by ocean bottom pressure sensors that monitor changes in ocean surface height.

Tsunami warning systems work great for near-field tsunamis but not for far-field tsunamis.

Once tsunami is detected, the arrival time of tsunami waves at various locations are quickly calculated.

Tsunami data collected in the open ocean are transmitted to warning centers via buoys floating at the ocean surface and Satellites.

B

Which mountain is the world’s tallest (measured from its base)?

Mt. Everest

Ojos del Salado

Mauna Kea

Kilauea

C

Which of the following statements concerning minerals and rocks is FALSE?

All minerals are naturally occurring.

All rocks are made of one or more minerals.

Minerals with the same chemical compositions share the same crystal structure.

The most common minerals in the Earth’s crust are silicate minerals.

C

Diamond is much stronger than graphite because their compositions are different. 

False

The building block of silicate minerals, silica tetrahedron, consists of silicon atoms and

Carbon atoms

Iron atoms

Oxygen atoms

Aluminum atoms

C

Rocks that form from lava flows are classified as

Pyroclastic material

Extrusive igneous rocks

Intrusive igneous rocks

Metamorphic rocks

B

Which of the following igneous rocks has the highest silica content and lightest in color (i.e., felsic)?

Rhyolite

Andesite

Basalt

Gabbro

A

Which of the following changes in the physical condition of rocks would promote melting of the rocks?

Decrease in temperature

Increase in pressure

Fracturing

Addition of water

D

Melting of the mantle produces which type of magmas?

Felsic

Rhyolitic

Andesitic

Basaltic

D

Decrease in silica content causes the viscosity of magma to increase.

False

Which combination best explains why some volcanic eruptions are explosive?

Low viscosity and abundant dissolved gas lead to pressure buildup

High viscosity and abundant dissolved gas lead to pressure buildup

Low viscosity and low gas content lead to pressure buildup

High viscosity and low gas content lead to pressure buildup

B

The type of magma that is generated at hot spots is

Ultramafic

Mafic

Intermediate

Felsic

B

What is the main mechanism of magma generation in subduction zones?

Increase in temperature

Decompression melting

Flux melting

Compression melting

C

Which of the following eruptive products is unlikely to form on Mt. Kilauea on the Big Island of Hawaii?

Pahoehoe

Pumice

Aa

Lava tube

B

Which of the following statements concerning pyroclastic material is FALSE?

Pyroclastic material are fragments of volcanic rocks.

Pyroclastic material forms during explosive eruptions.

Air-fall pyroclastic deposits are generally called tephra.

Pyroclastic flows occur when pyroclastic material is mixed with water.

D

Which of the following statements concerning stratovolcanoes is FALSE?

They have a steep-sided cone shape.

They are typically smaller than cinder cones.

The slope consists primarily of layers of pyroclastic material and lava flows.

They are common in subduction zones.

B

Shield volcanoes are formed commonly by eruption of rhyolitic lava.

False

Cinder cones are typically the product of which type of magma?

Ultramafic

Mafic

Intermediate

Felsic

B

Which of the following descriptions best describes calderas?

Crater formed by collapse of a lava dome and subsequent landslides.

Crater formed by explosive volcanic eruptions.

Crater formed by magmatic interaction with water.

Crater formed by the collapse of a volcano into a partially emptied magma chamber.

D

Phreatic eruption refers to eruption of steam and lava as a result of interaction between magma and water.

False

Vulcanian eruptions generate eruptive columns that are taller than Strombolian eruptions. 

True

Which of the following eruption types is the most explosive?

Strombolian

Vulcanian

Plinian

Hawaiian

C

Which of the following most likely leads to a Pelean eruption?

Collapse of a lava dome

Rapid cooling of lava at the surface

Eruption of low-viscosity magma

Release of volcanic gases without eruption

A

Which of the following is NOT a key mechanism for triggering pyroclastic flows?

Collapse of tall eruptive columns

Caldera formation

Bulge landslides

Dome collapse 

B

Which of the following volcanic hazards is the most widespread and frequent

Ash fall

Pyroclastic flow

Lava flow

Volcanic gases

A

Which of the following processes most commonly generates a lahar?

Collapse of a volcanic eruption column

Mixing of volcanic ash and debris with water

Dome collapse

Release of volcanic gases from magma

B

What three factors are used to determine a volcanic eruption’s ranking on the Volcanic Explosivity Index (VEI)?

Volume of ejected material, eruptive column height, eruption type

Volume of ejected material, size of accompanying earthquakes, duration of eruption

Size of the volcano prior to eruption, duration of eruption, distance to nearest city

Volume of ash column, farthest distance of most distal ejecta, heat of eruption

A

Which of the following statements concerning the size, frequency, and duration of volcanic eruptions is FALSE?

Small eruptions are common, but large eruptions are rare.

Most eruptions only last for a few days.

Many eruptions take more than 1 day to reach the explosive stage.

It’s harder to predict the end of an eruption than the start.

B

The tilt of the flank of volcanoes typically increases as magma ascends to the surface.

True

Which of the following instrument is used for lahar early warning systems?

Acoustic flow monitors

Correlation spectrometers

GPS

Tiltmeters 

A