Mt St Helens Flashcards

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1
Q

When was the eruption

A

18 May 1980

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2
Q

Where is Mt St Helens

A

In the South of the state of Washington

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3
Q

How many deaths

A

57

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4
Q

Height before eruption

A

9,677 feet

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5
Q

Height after eruption

A

8,363 feet

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6
Q

When did the volcano go dormant

A

1850

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7
Q

What economic activity was the most prevalent on the volcano

A

Logging

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8
Q

When did the volcano become slowly active

A

January 1980

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9
Q

What showed the growing pressure in the volcano

A

Bulge growing on North side due to magma rising from a fault

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10
Q

What was the impact of this growing threat on scientists and tourists

A

Scientists became highly concerned yet tourists were attracted

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11
Q

When was a state of emergency declared and why

A

3 April 1980

To keep the tourists away from the volcano

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12
Q

Who was allowed in the Red Zone

A

Law enforcement and scientists

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13
Q

Who was allowed in the wider Blue Zone

A

Loggers

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14
Q

Why was there anger around the danger zones

A

Some wanted stronger action (loggers wanting security and safety when working)

Some wanted less harsh restrictions (wanting to return home)

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15
Q

Magnitude of earthquake that triggered the eruption

A

5.1

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16
Q

What did the earthquake cause

A

Entire north side of the volcano slipped in the largest landslide in recorded history

17
Q

How fast did the landslide travel

A

155mph

18
Q

VEI

A

5

19
Q

How much sulphur dioxide was released

A

1.5 million tonnes

20
Q

Category

A

Plinian

21
Q

Why was the affected area so much larger than predicted

A

The eruption was a lateral blast, so covered a huge amount of land to the north, rather than the predicted small area around the whole volcano

22
Q

How much land did the pyroclastic flow destroy

A

600km²

23
Q

How far away were some trees burned

A

Over 30km

24
Q

What did airborne ash particles cause

A

Lightning, which triggered many forest fires

25
Q

How high were the ash clouds

A

23km

26
Q

Impacts of ash in the air

A

Pollution of water supplies
Killing livestock
Restricting air traffic

27
Q

What did ash settling on glaciers cause

A

It liquefied them, causing jökulhaups to destroy property and many bridges

28
Q

What happened with the jökulhaups?

A

They travelled 27km into the Columbia River
3,000,000m³ of material was transported
They blocked many rivers and damaged aquatic habitats

29
Q

What was destroyed

A

200 homes
47 bridges
185 miles of road
15 miles of railway
Many forests

30
Q

Recovery within a year

A

Many of the bridges and roads rebuilt
900,000 tonnes of ash removed from roads
Routes into other areas reestablished
Logging restarted

31
Q

What happened in 1980 - 1986

A

Numerous smaller eruptions

32
Q

What happened in the early 2000s

A

Lots of activity, with eruptions of steam and ash, as well as new lava domes forming in the crater of the volcano

33
Q

How did scientists use the event

A

To research how plants and animals could recover after a disaster such as this