Mount St Helens

Question 1

Where is Mount St Helens?

Answer 1

Mount St Helens is located in Washington State, USA, south of Seattle in the Cascade Range. It is on a destructive plate boundary.

Question 2

What happened on 20 March 1980?

Answer 2

There was an earthquake under the mountain, caused by the magma beginning to move.

Question 3

What happened on 25 March 1980?

Answer 3

There were 47 earthquakes.

Question 4

What happened on 26 March 1980?

Answer 4

Scientists issued a warning to the local people that they might have to be evacuated.

Question 5

What happened on 3 April 1980?

Answer 5

A bulge appeared on the side of the mountain.

Question 6

What happened on 30 April 1980?

Answer 6

Another warning was given and a 30km danger zone was established.

Question 7

What happened on 18 May 1980?

Answer 7

Mount St Helens erupted.

Question 8

Where did Mount St Helens erupt out of?

Answer 8

The top and the side (top was slightly blocked by solidified lava)

Question 9

How fast did pyroclastic flow move?

Answer 9

300km/hr

Question 10

How far did the pyroclastic flow flatten and burn trees

Answer 10

over 360km²

Question 11

What animals were killed by pyroclastic flow?

Answer 11

7000 animals were killed in the forest and 12 million salmon were killed in a fish farm

Question 12

How many people died?

Answer 12

57 people

Question 13

What did the hot magma do?

Answer 13

It melted the snow at the top of the mountain, which made mudslides.

Question 14

How fast did the mudslides move?

Answer 14

35 metres per second

Question 15

What did the ash do?

Answer 15

The ash made a cloud 24km high in the sky.

Question 16

What were the effects of the ash?

Answer 16

Planes had to be diverted
Made roads unusable
Ruined crops
Ruined machinery
Caused colourful sunsets in Europe for months after eruption

Question 17

How thick was the ash layer?

Answer 17

15cm thick

Question 18

What was the cost of the damage caused by just ash?

Answer 18

$175 million

Question 19

What happened to Mount St Helens after the eruption?

Answer 19

The side had blown out
The top had collapsed
Mount St Helens was 365 metres lower than it used to be

Question 20

How much did the US government give in aid to rebuild industry in the area and compensate people?

Answer 20

$951 million

Question 21

The area is now a tourist attraction. What has this done to the local economy?

Answer 21

It has made the local economy wealthier than it was before the eruption.

Question 22

What effect did the eruption have on the landscape?

Answer 22

The area now has an increased risk of flooding due to new landscape.