Presentation on theme: "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."— Presentation transcript:
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 18 th, 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".