Chapter 7 Quiz

All volcanic activity in a failed rift ceases once the rifting fails.

False

At Lake Nyos in 1986, a gas cloud wiped out all nearby plant and animal life.

False

Pyroclastic flows cannot travel down all sides of a volcano simultaneously.

False

What was the orgin 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

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 Pelee, Martinique,

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

Mt. St. Helens and Mt. Shasta

At Mt. St. Helens, about 60 people were killed in 1980, primarily by pyroclastic flows and effects related to lateral blast.

True

The most dangerous volcanoes tend to be in the same general plate-tectonic setting as the largest earthquakes in the world.

True

The plate-tectonic process responsible for volcanoes in the Pacific Northwest region of North America is identical to the cause of the region's great earthquakes - subduction of the Juan de Fuca Plate.

True

Volcanic eruptions can result in the formation of tsunamis.

True

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

ground deformation

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

the subduction of the Juan de Fuca Plate beneath North America