(GEO) Natural Disasters - Exam 2

Which of the following states has the lowest earthquake risk?

Florida

In 1959, the water stored behind Hegben Lake Dam in Montana began to slosh violently back and forth in a series of oscillating waves. These seiches were caused by __________________.

a sudden drop of the lake bottom during an earthquake

Slow flowing, more viscous basaltic lava commonly has a rough, blocky texture called ________.

aa

Viscous magmas are stored as a mostly solid, crystalline mush. It can be activated by which of the following?

an injection of new, hot magma and fracturing by fault movements that connect to isolated magma bodies and reduce the pressure

Tsunami that reach the shallow water slow down due to __________.

friction with the bottom and internal turbulence

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

has expanded in an east-west direction

The best course of action to take if you suspect a tsunami is headed your way is to __________.

head to higher ground and stay there

Tsunami are created by big "splashes" made in the deep ocean by all but which of the following?

hurricanes

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 25% chance of a magnitude ____________ earthquake here within the next 50 years .

6-7

About _________ of volcanism is associated with the edges of tectonic plates.

90%

Mt. Rainier, Washington, is number one on the danger list of many U.S. volcanologists because of its __________.

All of these choices are correct.

Rock may melt by _______________.

All of these choices are correct.

Spreading centers are an ideal location for volcanism because ______________.

All of these choices are correct.

The energy behind the 1902 pyroclastic flow that destroyed St. Pierre came from _________________.

All of these choices are correct.

Violent causes of death from volcanic eruptions include _______________.

All of these choices are correct.

Why are low latitudes the most dangerous latitudes to have a large volcanic eruption occur?

Ash and gases from low-latitude eruptions are spread around Earth to the greatest degree.

Seafloor spreading generates __________ magma.

Basaltic

The formation of a giant continental caldera includes all but which of the following?

Basaltic eruptions begin forming circular fractures surrounding the bulge.

The ________ Rift is the rift below the New Madrid region and is responsible for the seismic activity in the area.

Reelfoot

Spreading centers have relatively peaceful eruptions of magma because the __________.

SiO2-poor magma is at high temperatures.

What was the origin of the gas that killed 1,700 people in Cameroon in 1996?

It leaked upward from basaltic magma underlying a lake.

In 1883, __________ exploded and the resulting tsunami killed 36,000 people on Java and Sumatra.

Krakatau

The volcanic explosivity index (VEI) measures size of volcanic eruptions on a scale of 0 to 8. Between 1500 and 1980, one VEI 7 eruption occurred. This was ______________.

Tambora in 1815

The vulcanian eruption of Eyajafjallajokull in southern Iceland in 2010 resulted from __________.

glacial meltwater pouring into the magma chamber

Tsunami typically have _________ relative to wind-blown waves.

long periods and long wavelengths

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

more effectively in the older, more solid rocks

The dominant type of faulting in the Great Basin region is

normal faulting

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 ___________________.

of isostasy

The New Madrid earthquakes are apparently related to an old buried ____________.

rift zone

Detailed mapping of the ocean bottom around the Hawaiian Islands revealed a previously unrecognized tsunami source. What did geologists discover on the seafloor in this area?

slumps and debris avalanches formed by volcanic flank collapse

When magma is on the move at shallow depths it commonly generates a swarm of _____________.

small earthquakes referred to as harmonic tremors

A mantle hot spot has generated a long-lived plume beneath Yellowstone National Park, and the North American continent is moving __________ above it about 2 to 4 cm/yr.

southwestward

The 2004 Indian Ocean tsunami was generated by a magnitude 9.2 earthquake along __________ off the shore of Sumatra.

subduction zone

Prior to the 2004 event, the last major 1883 tsunami in the Indian Ocean struck in 1883 and killed about 36,000 people. This tsunami was caused by _________________.

the collapse of Indonesia's Krakatoa Volcano

The crustal thickness in the Great Basin is than mid - continental North American crust .

thicker than oceanic crust and thinner

Tsunami are typically about _________ high in the open ocean, and 6 to 15 m high on reaching shallow water.

1 m

Tsunami arrive as a series of several waves separated by periods typically in the _________ range.

10-60 minute

The most peaceful eruptions are __________ eruptions.

Icelandic type

The largest historic tsunami wave run-up ever recorded was caused by a massive rockfall into the water at ________________.

Lituya Bay, Alaska

In the United States, there was great concern in the early 1980s when earthquakes were frequent, including harmonic tremor, and four magnitude 6 earthquakes caused damage near __________.

Long Valley Caldera in California

The two most active Cascade Range volcanoes over the past 4,000 years are _______________.

Mt. St. Helens and Mt. Shasta

__________ eruptions are the most violent types of explosive eruptions.

Plinian-type

What is the volcanic explosivity index (VEI) of a Yellowstone super-eruption?

VEI of 8

The three 'Vs' of volcanology are __________________.

viscosity, volatiles, volume

Geologists have shown that the east coast of the United States faces a serious tsunami threat from ________.

volcanic flank collapse in the Canary Islands

Which of the following factors is the reason for the increase in Oklahoma earthquakes over the past 3 years?

wastewater disposal

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

western margin

A shield volcano has a great ___________.

width compared to its height

The great 1960 Chile earthquake (M 9.5) unleashed a tsunami that killed over 1,000 Chileans. These waves also killed 61 people in Hilo, Hawaii, 14 hours after the earthquake, and another 185 people in ________, 22.5 hours after the earthquake.

Japan

Pyroclastic debris is __________.

chucks of magma and rocks blown into the air by gas in a volcanic eruption