Mount St Helens 1980

Question 1

What caused Mount St Helens and when?

Answer 1

20th March 1980 with earthquakes

Question 2

Location of Mount St Helens

Answer 2

Cascades mountain range in Washington State, USA

Question 3

Plate boundary that forms Mount St Helens

Answer 3

Juan de Fuca plate subducting under North American plate (destructive)

Question 4

When was the Mount St Helens eruption?

Answer 4

18th May 1980

Question 5

What time was the Mount St Helens eruption?

Answer 5

8:32am

Question 6

What magnitude was the earthquake that set the Mount St Helens eruption off?

Answer 6

5.4 magnitude

Question 7

What sort of blast was it (Mount St Helens)?

Answer 7

Lateral blast (North side)

Question 8

How much of Mount St Helens disintegrated?

Answer 8

1,200 ft

Question 9

How high was the column of hot ash from Mount St Helens

Answer 9

10 miles

Question 10

How high was the column of hot ash from Mount St Helens

Answer 10

10 miles

Question 11

How far did the mudflows and lahars spread from Mount St Helens?

Answer 11

30 miles from the volcano

Question 12

Primary effects of Mount St Helens (5)

Answer 12

• Planes diverted
• Roads unusable
• Crops destroyed
• Ash fell in Portland
• Electricity cut

Question 13

How many people died from Mount St Helens

Answer 13

57

Question 14

How many salmon killed in the fish farm?

Answer 14

12 million

Question 15

How much was the total damage from Mount St Helens?

Answer 15

$175 million

Question 16

How many animals were killed in the forests?

Answer 16

7,000

Question 17

How much of Spirit Lake is still covered by logs now?

Answer 17

One third

Question 18

How fast were the lahars travelling from Mount St Helens

Answer 18

35 m/s

Question 19

Secondary effects of Mount St Helens (4)

Answer 19

• More tourists - better economy
• Area’s more prone to flooding
• More wild flowers - rejuvenating, ash is a good fertiliser
• Lots of new life from fertile soil, lots of animals

Question 20

How many people died from Mount St Helens (primary effect)

Answer 20

57

Question 21

How many salmon killed in the fish farm? (primary effect)

Answer 21

12 million

Question 22

How much was the total damage from Mount St Helens? (primary effect)

Answer 22

$175 million

Question 23

How many animals were killed in the forests? (primary effect)

Answer 23

7,000

Question 24

How much of Spirit Lake is still covered by logs now? (primary effect)

Answer 24

One third

Question 25

How fast were the lahars travelling? (primary effect)

Answer 25

35 m/s

Question 26

Short term responses of Mount St Helens (5)

Answer 26

• Get out of the area
• Search and Rescue
• Find shelter
• Give out masks for the ash
• Clear ash from roads

Question 27

Long term responses of Mount St Helens (3)

Answer 27

• Rebuilding bridges and buildings
• Clearing drains to prevent flooding
• Re-planting trees

Question 28

When was it declared a national monument? (long term response)

Answer 28

1982

Question 29

How many trees were flattened? (primary effect)

Answer 29

12 miles

Question 30

How deep was Spirit Lake filled with trees

Answer 30

60m