Geology 104 - Test 2 Study Guide

Energy is stored in rocks adjacent to the site of a future earthquake as

Elastic strain

Alluvial soils that comprise floodplains are poor soils for agricultural purposes.

FALSE

Because they occur within plate interiors, seismologists can make estimates and short term predictions of the size, location, and recurrence intervals of intraplate earthquakes with incredible certainty.

FALSE

Deep-focus earthquakes are usually the most destructive because the seismic shaking is amplified as the waves approach the surface.

FALSE

Engineers will consider building only on slopes with a factor of safety less than 1.

FALSE

Given their great speed, it is impossible to warn of a tsunami before it strikes land.

FALSE

One of the best ways to prevent landslides is with warning systems.

FALSE

The 2004 Indonesian/Indian Ocean tsunami came as a complete surprise to scientists working in the area.

FALSE

The San Andreas Fault is highly likely to generate tsunamis.

FALSE

The terms "subsidence" and "flow" are used interchangeably to describe a particular type of landslide.

FALSE

Most earthquakes that occur are intraplate earthquakes.

False

Compared to interplate EQ, it is ___ to locate faults at the surface in intraplate areas because ___

Harder, they are typically buried by sediment

The Mercalli Scale is a scale from ________.

I to XII that rates the structural damage due to an earthquake

The 2004 Indian Ocean tsunami originated off the coast of the island of Sumatra, which is part of the country of ________.

Indonesia

The 1700 AD tsunami generated by a large earthquake on the Cascadia subduction zone in the Pacific Northwest was dated most precisely using

Japanese tsunami records

The time intervals between major intraplate EQ is ___ (longer or shorter) than typical intervals between major interplate EQ.

LONGER

________ refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking.

Liquefaction

Tsunamis are generated by

NOT: earthquake waves shaking the ocean floor

Oxford, MS would be most likely to feel shaking associated with the next "big one" occurring in the ___ fault zone.

New Madrid

Earthquakes in Hawaii are caused by activity along which type of plate boundary?

None, Associated with Volcanos

The Wasatch Fault is a ___ fault that runs along the western edge of the Wasatch Mountain Range. A great earthquake along this fault could significantly impact the populated area of ___.

Normal, Salt Lake City

A fault is called an ________ fault if it has experienced movement in the last 10,000 years.

Potentially active

There is potential for a great quake along the Cascadia Subduction zone, with possible damage affecting northern California, Oregon, Washington, Vancouver, and Victoria. This zone is an area of thrust faulting, a type of ___ faulting commonly found at a ___ plate boundary.

Reverse, convergent

Large intraplate EQ occurred in the US in the 1800s centered in ___.

SC and MO

Rocks found in the plate interiors tend to be ___ than those near plate boundaries and typically transmit seismic energy greater distances from the epicenter than rocks near plate boundaries.

Stronger, colder, denser, older

Downstream floods typically cover a large area and are produced when long-lasting storms saturate soils and increase runoff into streams and rivers.

TRUE

Earthquakes are the only source of tsunamis.

TRUE

Earthquakes result from the sudden release of elastic strain energy previously stored in rocks surrounding a zone of fault movement.

TRUE

If discharge is held constant, decreasing the size (cross-sectional area) of a river channel would result in an increased flow velocity.

TRUE

It is safer to be on the open ocean than in the harbor when a tsunami arrives.

TRUE

Mudflows typically occur in saturated materials.

TRUE

On earthquake distribution maps, the boundaries of the Earth's tectonic plates are shown as zones of high seismic activity.

TRUE

Some large earthquakes are preceded by smaller magnitude foreshocks.

TRUE

Subsidence of overlying materials may be caused by collapse of "pillars" in a location where the "room and pillar" system of mining has formerly been used.

TRUE

The Cascadia subduction zone in the Pacific Northwest is a location at which tsunamis are generated.

TRUE

The geographic distribution of liquefaction features, such as sand blows, of the same age can be used to estimate the epicenter and magnitude of the prehistoric earthquake that created the features.

TRUE

Tsunamis can cause damage thousands of miles from their source.

TRUE

Which one of the following statements concerning foci and epicenters is correct?

The epicenter is at the surface directly above the focus where the earthquake initiates.

In the United States, earthquakes occurring west of the Rocky Mountains are interplate earthquakes.

True

Intraplate earthquakes occur

Within plate interiors

________ is the maximum possible damage designation on the Modified Mercalli scale.

XII

Caves form in rocks when slightly ________ groundwater dissolves certain soluble rocks.

acidic

An ________ fan is a fan-shaped deposit that forms when a stream flows from a steep mountain channel onto a flat plain.

alluvial

The ________ is directly related to the Richter earthquake-magnitude rating.

amplitude of the recorded seismic waves

p-waves

are fastest

A lahar is a mudflow created when loose volcanic ________ becomes saturated with water. Lahars can be very damaging and are a serious secondary effect of volcanic activity.

ash

The region drained by a single river or river system is called a drainage ________, or watershed.

basin

A ________ channel pattern tends to be wide and shallow, with numerous gravel bars, and may occur in areas with steeper slopes.

braided

A ________ forms where a river flows into the ocean or another larger water body.

channel

Paracutin in central Mexico is an example of a ________ ________, or a small volcano that can form relatively quickly from primarily explosive activity.

cinder cone

Andesite, which forms from magmas with intermediate silica content, is a rock commonly created by ________ volcanoes.

composite

Mt. St. Helens is an example of a ________ volcano.

composite

The cone shape of ________ volcanoes is a result of the combination of lava flows and explosive activity that forms them.

composite

________ volcanoes are also known as stratovolcanoes.

composite

________ volcanoes are the type of volcano responsible for the most death and destruction.

composite

The time of year can impact slope stability, since the depth to the water ________ changes seasonally.

content

The "Ring of Fire" occurs along subduction zones, which are associated with ________ plate boundaries.

convergent

Very slow, gradual displacement along a fault that is not accompanied by felt earthquakes is called tectonic ________.

creep

Slumps (aka rotational slides) differ from translational slides in that soil or rock slides down a ________ slip plane.

curved

Once a large tsunami is generated, it is least noticeable in (deep or shallow) ________ water.

deep

One of the best ways to decrease landslide potential on a slope is to control ________.

drainage

The catastrophic 2004 tsunami was generated by a(n)

earthquake

Moving magma and volcanic fluids may trigger ________, which are often the earliest warning of impending volcanic eruptions.

earthquakes

________ in Thailand are at least one type of animal that appear to have sensed the impending 2004 tsunami.

elephants

The ________ is the point on the surface directly above the site of initial earthquake rupture.

epicenter

The primary human adjustment to volcanic activity is ________.

evacuation

A fracture or fracture system along which rocks have been displaced is called a ________.

fault

In upper parts of drainage basins, intense rainfall over a relatively small area may cause a ________ flood, which can be quite severe locally.

flash

________ is the natural process of overbank flow.

flooding

The flat surface adjacent to a river channel is called a ________.

floodplain

The term viscosity may be defined as a substance's resistance to ________.

flow

Lava with a low silica content and, therefore, a low viscosity, will more likely behave in which of the following ways?

flow down the sides of a volcano

The ________ is the site of initial rupturing associated with an earthquake.

focus

Old Faithful is a ________ located at Yellowstone National Park that periodically shoots steam and hot water into the air at Earth's surface.

geyser

A river's slope, also called its ________, is the vertical drop in elevation over a horizontal distance that it flows.

gradient

Japan, Mexico, the Phillipines, and Indonesia have many active volcanoes and are countries with a ________ (high or low) population density.

high

In some volcanic areas, groundwater is heated when it comes in contact with hot rock, and it may discharge at the surface as a ________ ________.

hot spring

How did the population of Heimaey, Iceland reduce damage from advancing lava flows of Mt. Helgafell toward their island?

hydraulic cooling

In what region did a major tsunami strike in late 2004?

indian ocean

Volcanic debris flows and mudflows are commonly referred to as ________.

lahars

The 1998 tsunami in Papua New Guinea was generated by a submarine ________.

landslide

The shaking associated with a large earthquake in the New Madrid Fault zone would be felt over a much ___ (larger or smaller) area than the shaking caused by a similar magnitude earthquake occurring in California.

larger

An explosion of gas and ash from the side of a volcano is called a ________ blast.

lateral

Magma that reaches Earth's surface through volcanic activity is called ________.

lava

Caves and sinkholes commonly form in ________, which is a sedimentary rock composed of the mineral calcite.

limestone

Pahoehoe is faster moving than aa, because it has a ________ (lower or higher) viscosity.

lower

A common name for molten rock is ________.

magma

A ________ river channel has many bends that migrate back and forth across the floodplain.

meandering

Tsunamis can be detected on the path through the open ocean by

measurement of changes in pressure exerted on the sea bottom by the water column

Overpumping of groundwater in an area may be referred to as "groundwater ________."

mining

The ________ magnitude scale is a measure of the energy released by an earthquake. It does not directly measure the extent of building damage.

moment

A strike-slip fault involves horizontal displacement and is described as either left-lateral or right-lateral. A dip-slip fault involves vertical displacement and is either a reverse fault or a ________ fault.

normal

Why was building damage so extensive in the 1985 Mexico City quake?

not built on solid ground

Which of the following is not a way that humans have been known to induce earthquakes?

oversized trampolines in backyards

An abandoned meandering river channel that has filled with water is called an ________ lake.

oxbow

________ have the highest velocities.

p-waves

The "Ring of Fire" is an area with many volcanoes that surrounds the ________ Ocean.

pacific

Which of the following has the lowest viscosity?

pepsi

The inside of a meander loop where sediment is deposited is called a ________ bar, and the outside of a bend where erosion occurs is called the cutbank

point

Ash flows, also called nuee ardentes or ________ flows, are large volumes of incredibly hot, very fast-moving material that can incinterate everything in their path.

pyroclastic

The common rock type produced by volcanic domes, from viscous magma with relatively high silica content, is called _________.

rhyolite

Which of the following foundation materials is most stable during earthquake shaking?

rock

The ratio of resisting forces to driving forces acting on a slope is referred to as its factor of ________.

safety

The instrument used to record earthquake vibrations is called a ________.

seismograph

An earthquake scientist is called a ________.

seismologist

Basalt is the type of rock that forms from the low silica, low viscosity lava emitted from ________ volcanoes.

shield

The Hawaiian Islands are examples of ________ volcanoes.

shield

Which type of volcano is most associated with subduction zones?

shield

A ________ is a circular area of subsidence into a subterranean void.

sinkhole

A ________ plane is a geologic surface of weakness (such as fractures, weak layers, bedding, or foliation planes) along which slope failure may occur.

slip

The long-term rate of movement along a fault is known as its ________ rate.

slip-rate

S waves travel through _____ and P waves can travel through _____ and _____.

solids; liquids, solids

The height of the water in a river at a particular time is called the ________.

stage

Mining of salt and coal, excessive groundwater pumping, and natural groundwater action have been known to cause to land ________.

subsidence

The ________ is a direct measure of the distance from a seismic receiving station to the focus of a distant earthquake.

time interval between the first P and S- wave arrivals

A tsunami warning system includes seismometers, surface buoys equipped with a bottom sensor (known as a ________), and communication systems.

tsunameter

A seismic sea wave induced by an earthquake is called a _________.

tsunami

Lava and pyroclastic debris erupt at Earth's surface through circular conduits or elongated fissures called volcanic ________

vents

Similar to the way your pancake syrup will be "more runny" when you warm it in the microwave, the ________ of magma is lower when temperatures are higher.

viscosity

The giant tsunami that struck Indonesia in 1883 was caused by a(n)

volcanic eruption

While there may be an increase in resisting forces as roots hold material in place, vegetation may also contribute to driving forces due by adding additional ________ to the slope.

weight

Volcanic hazards in the U.S. exist primarily along the ________ coast.

west

Which is not considered a possible localized cause of intraplate earthquakes?

Changes in tides

Seismic gaps are ________.

Areas along active fault zones or within regions that are likely to produce large earthquakes but have not caused on recently; unusually quiet zones along known active faults

Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with magnitude 5.5?

3000

The earthquake risk in Alaska is due to a tectonic setting most similar to which of these?

Cascadia subduction zone