Unit 4- Natural Disasters Test Study Guide (Chapters 6, 7, and 8)

__________ eruptions are the most violent types of explosive eruptions.

Plinian-type

In August 1986, a gigantic volume of __________ belched forth from Lake Nyos in Cameroon and swept down the adjacent valleys asphyxiating 1,700 people.

carbon dioxide

The presence of water ________ the melting point of rock.

lowers

Tsunami wavelengths can be as great as _________.

780 km

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

90%

Regarding the Fukushima Daiichi nuclear disaster, the Tokyo Electric Power Company (TEPCO) hopes that they will be able to remove the melted nuclear fuel masses in __________.

30-40 years

The viscosity of magma is lowered by __________.

All of these choices are correct. Including: A) increasing temperature B) decreasing crystal content C) decreasing SiO2 content

The typical trend in a rising plume of subduction-zone magma is to increase the ____________.

All of these choices are correct. Including: A) percentage of SiO2 B) viscosity C) explosive potential of the magma by holding in the gases more tightly

Spreading centers are an ideal location for volcanism because ______________.

All of these choices are correct. Including: A) they sit above the high-temperature asthenosphere B) the asthenosphere rock has low percentages of SiO2 C) the oceanic plates pull apart causing hot asthenosphere rock to rise and undergo decompression melting to form magma that continues to rise)

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.

During the 1990s, hundreds of trees were killed at Mammoth Mountain, California, by the diffuse emission of _________ gas.

CO2

The most famous of all volcanoes probably is Vesuvius, and the most famous of its eruptions are those of 79 CE, which buried the cities of ____________?

Pompeii and Herculaneum

____________ in the Aegean Sea underwent an explosive series of eruptions around 1628 BCE that buried the Bronze Age city of Akrotiri on Thera to depths of 70 meters.

Santorini

The great 1964 Alaska earthquake (M 9.2) set off a tsunami that killed 122 people along the state's sparsely populated coastline. This tsunami also killed 12 people in the state of _________.

California

In 1868, the USS Wateree was carried several miles inland by a tsunami along the coast of ______.

Chile

The 2004 _________ Ocean tsunami killed an estimated 245,000 people in 13 countries.

Indian

Most of the 245,000 deaths from the 2004 Indian Ocean tsunami occurred in _______.

Indonesia

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.

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

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

Krakatau

__________ are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows that solidify to form protective caps.

Stratovolcanoes

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

Tsunami events at a coastline __________.

can start with a drawdown or rising of the sea

The Toba eruption 74,000 years ago may have __________.

caused a great reduction in the worldwide human population

A well-formed conical volcano located above an active subduction zone that has not erupted in 12,000 years is __________.

dormant, but will likely erupt again at some point

In 1964, 12 people were killed during a tsunami at Crescent City, California. All of these fatalities were caused by the _______ wave, which was the highest in the series.

fifth

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

friction with the bottom and internal turbulence

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

glacial meltwater pouring into the magma chamber

Several geologic phenomena are being studied as signs of an impending volcanic eruption. These include seismic waves, ______________, and the release of gases.

ground deformation

Tsunami is a Japanese word that means __________ waves.

harbor

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

The Mt. Pinatubo endangered people, animals, and property when its 1991 eruption resulted in __________.

lahars and pyroclastic flows

Most rifting occurs at spreading centers __________.

located below sea level

Tsunami typically have _________ relative to wind-blown waves.

long periods and long wavelengths

Rock may melt by _______________.

lowering the pressure on it raising its temperature increasing its water content

The number of active "hot spots" on Earth over the last 10 million years active is __________.

more than 100

Most Icelandic eruptions are __________.

peaceful fissure eruptions

If basaltic lava reaches the sea or a lake, it cools rapidly into ____________ lava.

pillow

Dome collapse, overspilling crater rim, direct blast, and eruption column collapse are all ways to generate __________.

pyroclastic flows

Modern tsunami warning systems primarily use __________.

sea surface buoys and ocean bottom pressure sensors

The trees that died in the Pacific Northwest after the great earthquake of 1700 were killed by __________.

seawater after faulting dropped the land below sea level

A _________ is an oscillating wave that sloshes back and forth within an enclosed body of water such as a sea, bay, lake, or swimming pool.

seiche

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

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

Some of Earth's most beautiful mountains are ________, including Mt. Kilimanjaro in Tanzania, Mt. Shasta in California, Mt. Rainier in Washington, and Mt. Fuji in Japan

stratovolcanoes

Earthquake-related tsunami are created by sub sea fault movements with pronounced vertical offsets of the seafloor. Such movements occur most commonly along __________________.

subduction zones

What erupts in a geyser?

superheated water and steam

Silicon and oxygen link up to form the silicon-oxygen ______________.

tetrahedron

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

What is the cause of volcanism at Italy's Vesuvius, Stromboli, Vulcano, and Etna?

the subduction of Mediterranean seafloor beneath Europe

Active volcanoes today in Oregon and Washington, including Mt. St. Helens, result from _________________.

the subduction of the Juan de Fuca Plate beneath North America

Most of the people killed by the Mount St. Helens eruption of 1980 __________.

) had gone around barriers meant to keep people out of 'harms' way

The Japanese Tsunami inflicted destruction along the coast and in Sendai, the wave travelled inland __________.

10 km

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

10- to 60- minutes

Mineral growth in magmas at the surface with temperatures around 1,000 to 1,200°C occurs in the following way

A) Iron and magnesium will link up with aluminum and the silicon-oxygen tetrahedron as magma temperature decreases to sequentially form four distinct and discontinuous families of minerals—olivine, pyroxene, amphibole, and biotite mica. B) Calcium will combine with aluminum and the silicon-oxygen tetrahedron to begin forming the plagioclase feldspar family, a continuous and gradational series of minerals.

Why does the magma from some volcanoes flow smoothly and relatively peacefully, while the magma from other volcanoes blasts forth violently and deals death over wide areas?

A) differences in the chemical and mineral makeup of magmas B) variations in the temperature, water and gas content, and viscosity of magmas C) different geographic positions with respect to hot spots and edges of tectonic plates

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

A) great height B) extensive glacial cap C) frequent earthquakes D) active hot-water spring systems, which have weakened the mountain internally

Violent causes of death from volcanic eruptions include _______________.

A) pyroclastic flows B) tsunami C) lahars D) poison gases

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

A) the blast of the volcano B) gravity C) gas escaping from pieces of airborne pyroclastic material, creating a "popcorn" effect

Hawaiian volcanoes unlikely to erupt include _________________.

Diamond Head, Oahu

The most peaceful eruptions are __________ eruptions.

Icelandic type

This volcano erupted in 1883 in the Sunda Strait between Sumatra and Java, exploding with a loudness heard 3,000 miles away, then collapsing into its magma chamber, making a caldera and setting off a tsunami that killed at least 36,000 people.

Krakatoa

During the summer of 1783, the greatest lava eruption of historic times poured forth at _________, accompanied by the release of an enormous volume of gases that enshrouded much of northern Europe in a "dry fog" or blue haze rich in SO2 (one of the visible components of today's urban smog).

Laki, Iceland

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

Lassen Peak and Newberry Volcano

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

On 8 May 1902, a massive eruption of __________ killed 30,000 people in the town of St. Pierre.

Mont Pelée, Martinique,

Crater Lake, Oregon, fills the caldera of ____________ which collapsed about 7,600 years ago

Mt. Mazama

A genuine success story of advance warning before a large eruption occurred in the Philippines in 1991 before the climactic eruption of _________________.

Mt. Pinatubo

In 1985, __________ produced a minor eruption that melted part of a glacier near its summit, sending a lahar down its slopes and killing at least 22,000 people.

Nevado Del Ruiz, Colombia,

On 20 February 1943, a new volcano named __________, a scoria cone, was born when an eruption rose up through a farm field near a village in Mexico.

Paricutin

Volcanic eruptions with which of the following VEIs happen the most often?

VEI of 3

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

VEI of 8

Which of the following statements is true regarding tsunami and volcanoes?

Volcanic eruptions can result in tsunami as they explode, collapse, or send debris into the water.

_________ eruptions are common first phases in the eruptions of volcanoes as they "clear their throats" before emitting larger eruptions.

Vulcanian-type

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

a subduction zone

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

A caldera collapse occurs ________________.

after the magma chamber is mostly empty

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

The captain of a ship tells you that he once experienced a huge tsunami while sailing in the Pacific Ocean several hundred miles from any landmass. You decide that this sounds a little far-fetched because _________.

tsunami are rarely felt in deep water because they have long wavelengths and low heights

The three 'Vs' of volcanology are __________________.

viscosity, volatiles, and 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

In magma, __________ is the most abundant dissolved gas.

water vapor (H2O)

A shield volcano has a great ___________.

width compared to its height

Multiplying 1.25 by the square root of the wavelength results in the velocity of a __________.

wind-blown wave in deep water

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

1m

Most tsunami travel at speeds of _________ miles per hour.

420 to 480

The 1946 April Fool's Day tsunami at Hilo, Hawaii, was caused by an earthquake near ________.

Alaska

The 1964 tsunami that killed 12 people at Crescent City, California, was caused by a major earthquake in _________.

Alaska

Which of the follows statements about tsunami in the deep ocean?

They are always "feeling" the bottom

The deadly 1998 tsunami in Papua New Guinea was caused by ________.

an undersea landslide triggered by an earthquake

The theoretical velocity of a tsunami in the deep ocean is calculated by taking the square root of the product of __________.

the acceleration due to gravity and the depth of the ocean