How did mount st Helens become a volcano?

Answer 1

Mount St. Helens was created by the interactions of the North American plate and the Juan de Fuca plate. The Juan de Fuca plate is an oceanic plate, made of material which is denser than continental plates, such as the North American plate. The Juan de Fuca plate and the North American plate are currently moving towards each other, and Juan de Fuca plate is going underneath the North American plate because it is denser. This allows for magma to come to the surface, and it creates a volcano.

Answer 2

Mount Saint Helens, like all of the volcanoes in the Cascades mountain range, is a subduction zone volcano. Its supply of lava results from the Pacific plate being forced down under the North American plate. The resulting friction melts rock and forces it upward through cracks, feeding the volcanoes. Because the sediment on the Pacific plate is saturated with water from the ocean, lots of water is incorporated into the melted rock, which results in steam explosions during eruptions of these volcanoes.

Answer 3

Mount St Helens did not a become a lava dome; a lava dome grew in the summit crater. It was the result of the volcano slowly erupting highly viscous dacite lava with a low gas content.

Answer 4

No. Although Mount St Helens has a lava dome in it, the volcano itself is a stratovolcano.