Mt. St. Helens Eruption Flashcard

Front

What was the most destructive event on the morning of May 18, 1980, during the Mt. St. Helens eruption?

Back

The directed blast.

Front

What was the rate of northward movement of the bulge on Mt. St. Helens prior to the eruption?

Back

6 feet a day.

Front

What did USGS scientists learn about explosive eruptions from the Mt. St. Helens event?

Back

They learned how to anticipate them, study hot fresh deposits, and mitigate their consequences.

Front

What insights did subsequent eruptions of Mt. St. Helens provide to scientists?

Back

They helped scientists learn how to mitigate the consequences of eruptions, predict eruptions accurately, and understand how volcanoes work.

Front

How quickly did the directed blast from Mt. St. Helens destroy an area of 230 square miles?

Back

In 9 minutes.

Front

Define 'pyroclastic flow' in the context of volcanic eruptions.

Back

A fast-moving current of hot gas and volcanic matter that flows down the slopes of a volcano.

Front

What is a 'directed blast' in volcanic terms?

Back

A lateral explosion that occurs when volcanic pressure is released, sending ash and debris in a specific direction.

Front

Explain the significance of the bulge on Mt. St. Helens before the eruption.

Back

The bulge indicated magma accumulation beneath the surface, signaling potential volcanic activity.

Front

What role did the USGS play during the Mt. St. Helens eruption?

Back

The USGS monitored the volcano and provided critical information on eruption predictions and safety measures.

Front

What is the importance of studying hot fresh deposits after a volcanic eruption?

Back

It helps scientists understand the eruption dynamics and the materials ejected during the event.