Mt. St. Helens

By: Mrs. Gordon

Location

• Washington, USA

• 96 miles South of Seattle, WA

• 50 miles North of Portland, OR

• Elevation: 8,363 ft

Type of Volcano• Mt. St. Helens is a

stratovolcano (also known as a composite volcano). – Tall, steep sides, cone-

shaped– Alternating layers of ash

and tephra• It is located near a

subduction zone of the west coast of the United States.

Eruptive History• Mt St Helens’ most famous eruption happened on May 18th, 1980 after a

magnitude 5.1 earthquake triggered the largest landslide in recorded history.– 1,314 feet of elevation on the mountain was removed in the blast.– The blast devastated 229 square miles of forest.– The ash plume reached about 80,000 feet in less than 15 minutes spread

across US in 3 days; circled Earth in 15 days.– 57 people were killed.

Positives and Negatives

• + + + It is a world famous tourist attraction and an active scientific volcano laboratory.

• - - - - Many people still live near the volcano, exposing themselves to future danger. Larger, longer lasting eruptions have occurred in the volcano's past and are likely to occur in the future.

Interesting Facts• 21 people were never recovered from the

1980 blast zone.

• Northwest Indians told early explorers about the firey Mount St. Helens. The Indian name for the mountain, Louwala-Clough, means "smoking mountain".

Sources• http://members.virtualtourist.com/m/33c38/da47f/

• http://www.diggersrealm.com/mt/archives/000172.html

• http://www.ngdc.noaa.gov/hazard/stratoguide/helenfact.html

• http://pubs.usgs.gov/fs/2000/fs036-00/

• http://wsm.wsu.edu/s/index.php?id=392

• http://www.olywa.net/radu/valerie/StHelens.html