Geologists call Mount St. Helens a composite volcano (or stratovolcano), a term for steep-sided, often symmetrical cones constructed of alternating layers of lava flows, ash, and other volcanic debris. Composite volcanoes tend to erupt explosively and pose considerable danger to nearby life and property.
Is Mt Saint Helens a composite?
Mount St. Helens is an example of a composite or stratovolcano. These are explosive volcanoes that are generally steep-sided, symmetrical cones built up by the accumulation of debris from previous eruptions and consist of alternating layers of lava flows, volcanic ash and cinder.
What type of composition is Mount St. Helens?
Mount St. Helens is a stratovolcano, a steep-sided volcano located in the Pacific Northwest region of the United States in the state of Washington.
What type of rock is Mount St. Helens made of?
Like most other volcanoes in the Cascade Range, Mount St. Helens is a great cone of rubble consisting of lava rock interlayered with ash, pumice and other deposits. The mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted.
What type of landform is Mt St Helens?
stratovolcano
Mount St. Helens is a stratovolcano of the Cascadia volcanic arc well known worldwide for its volcanic collapse and eruption in 1980, which caused considerable destruction and changed the geomorphology of the volcano and of a considerable portion of its surroundings.
What volcano is composite?
Composite volcanoes are tall, symetrically shaped, with steep sides, sometimes rising 10,000 feet high. They are built of alternating layers of lava flows, volcanic ash, and cinders. Famous composite volcanoes include Mount Fuji in Japan, Mount Shasta and Mount Lassen in California, Mount St.
What volcano is a composite type?
stratovolcano
A composite volcano, also known as a stratovolcano is a cone-shaped volcano built from several layers of lava, pumice, ash, and tephra. Due to its viscous lava, a composite volcano tends to form tall peaks rather than rounded cones. Mount Fuji in Japan and Mount Shasta in California are examples of composite volcanoes.
Is Mount St. Helens cinder cone shield or composite?
composite volcano
Geologists call Mount St. Helens a composite volcano (or stratovolcano), a term for steepsided, often symmetrical cones constructed of alternating layers of lava flows, ash, and other volcanic debris.
Is the Mount St. Helens destructive or constructive?
Destructive
Destructive; The lateral blast erupted lava from Mount St. Helens. This further destroyed the mountain and the surrounding forest. Both; Ash and pumice from the plume injured trees and buried plants and crops.
How is Mt. St. Helens formed?
The stratovolcano known as Mount St. Helens or Loowit formed when the Juan de Fuca tectonic plate subducted under the North American one.
What type of rock is basalt?
Basalt is a hard, black volcanic rock. Basalt is the most common rock type in the Earth’s crust. Depending on how it is erupted, basalt can be hard and massive (Figure 1) or crumbly and full of bubbles (Figure 2).
What type of rock is Mount?
Mountains consist of a combination of igneous, metamorphic, or sedimentary rock, depending on how they are formed.
What kind of material is being ejected by the Mount St. Helens volcano?
Helens involved several distinct large disturbances—a huge debris avalanche, an explosive lateral blast out the mountain’s north side, mudflows, hurricane-force winds of hot gases, and ejected volcanic rock and ash (tephra).
Is Mt Rainier a composite volcano?
Mount Rainier is an episodically active composite volcano, also called a stratovolcano. Volcanic activity began between one half and one million years ago, with the most recent eruption cycle ending about 1,000 years ago.
What plates made St Helens?
Mount St. Helens sits on the plate boundary between Juan de Fuca and the North American plates (map above). The boundary is part of the so- called ‘Ring of Fire’ – the string of volcanoes that congregate around the margin of the Pacific Ocean. The plate margin that created Mount St.
Will Mount St. Helens erupt again?
We know that Mount St. Helens is the volcano in the Cascades most likely to erupt again in our lifetimes. It is likely that the types, frequencies, and magnitudes of past activity will be repeated in the future.
What are three composite volcanoes?
Some of the most conspicuous and beautiful mountains in the world are composite volcanoes, including Mount Fuji in Japan, Mount Cotopaxi in Ecuador, Mount Shasta in California, Mount Hood in Oregon, and Mount St. Helens and Mount Rainier in Washington.
How do you know if a volcano is composite?
Composite volcanoes have the following characteristics:
- Acidic lava, which is very viscous (sticky).
- Steep sides as the lava doesn’t flow very far before it solidifies.
- Alternate layers of ash and lava. For this reason, they’re also known as stratovolcanoes .
- Violent eruptions.
- Longer periods between eruptions.
What are the three types of composite volcanoes?
What are the three main volcanoes? There are three main types of volcano – composite or strato, shield and dome. Composite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows.
What eruption forms a composite volcano?
Composite volcanoes form in subduction zones when an oceanic plate subducts beneath a continental plate. The volcanoes often contain more than one type of lava. Andesite is the main type of lava that creates stratovolcanoes. Stratovolcano is another name for composite volcanoes.
What are composite and shield volcanoes?
Composite volcanoes are tall, steep cones that produce explosive eruptions. Shield volcanoes form very large, gently sloped mounds from effusive eruptions. Cinder cones are the smallest volcanoes and result from accumulation of many small fragments of ejected material.