Exam 8: Volcanic Activity

________ eruptions are among the most violent and largest known.

________ are volcanic mudflows.

Viscosity of a magma is controlled by

Lahars are usually produced by saturation of thick volcanic ash.

Hundreds of residents near a dormant volcano at Lake Nyos died when

Tens of thousands of people were killed in the 1991 Pinatubo eruption because of a lack of prediction of the eruption.

________ is the primary human adjustment to volcanic activity.

Why is the geologic history of a volcano important in hazard prediction?

The May 18, 1980, eruption of Mt. St. Helens began with a massive ________.

Viscosity is a primary control on the nature of volcanic activity.

What is the principal difference between craters and calderas?

________ activity beneath a volcano is an indication of moving magma.

The 1991 eruption of Mt. Pinatubo cooled the Earth's climate the following year.

The 1980 eruption of Mt. St. Helens produced large lava flows that filled the nearby river valleys.

Shield volcanoes typically consist of the rock type ________.

A shield volcano is typically andesitic in composition.

The citizens of Heimaey, Iceland, succeeded in stopping a lava flow from blocking their harbor.

Composite volcanoes consist almost completely of lava flows.

Why were the citizens of Heimaey, Iceland, successful in stopping the lava flow that threatened their harbor?

Lava flows are the most dangerous of the primary volcanic hazards.