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.
What type of volcano is Mt 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. Sitting about 97 miles south of Seattle and 52 miles northeast of Portland, Oregon, Mt.
What type of volcano is Mt St Helens and why did it form?
Mount St. Helens is primarily an explosive dacite volcano with a complex magmatic system. The volcano was formed during four eruptive stages beginning about 275,000 years ago and has been the most active volcano in the Cascade Range during the Holocene.
Is Mt St Helens a shield volcano?
Mount St. The two volcanoes are also different shapes: Kilauea is a gently sloping shield volcano, unlike Mount St. Helens, which is a steep-sided stratovolcano, also known as a composite volcano. This allows for different types of eruptions, with shield volcanoes being much less violent.
What type of volcano is Mount St. Helens quizlet?
St. Helens was a stratovolcano, after all) which corresponded to layers and striations found in the crater of the volcano.
Is Mt St Helens divergent or convergent?
Mt. St. Helens is a volcano in Washington, near the Oregon border, in the Cascade Range. The Cascade Volcanoes, which stretch all from British Columbia through Northern California, are stratovolcanoes that have formed inland from a convergent plate boundary, where ocean crust is subducting below the continent.
What type of volcano is Mt St Helens shield or composite?
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. Composite volcanoes tend to erupt explosively and pose considerable danger to nearby life and property.
Is Mt St Helens composite cinder cone volcano?
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.
Did Mt St Helens have lava?
Lava flows from Mount St. Helens typically affect areas within 6 mi (10 km) of the vent. However, two basalt flows erupted about 1,700 years ago extended about 10 mi (16 km) from the summit; one of them contains the Ape Cave lava tube. Lava flows typically follow stream drainages and spread out in areas of low relief.
How did Mt Saint Helens form?
Mt St Helens is a major stratovolcano in the Cascades Range, all of which have formed as a result of the ongoing subduction of the Juan de Fuca tectonic plate beneath the western coast of North America. Prior to 1980, Mt St Helens was a classical cone-shaped volcano, and a well-visited site on the tourist trail.
Which of the following are types of volcanoes?
Geologists generally group volcanoes into four main kinds–cinder cones, composite volcanoes, shield volcanoes, and lava domes.
When did Mt St Helens erupt quizlet?
A set of Questions and answers for the Mount St Helens volcanic eruption on May 18th 1980.
How does an eruption of Mount St Helens differ from an eruption of Kilauea quizlet?
The eruption of Mount St. Helens (5/18/1980) was a violent, explosive event where the volcano blew out the north flank, spreading ash and rock debris up to 18 km around. The typical eruption of Kilauea, by contrast, is gradual with lava slowing pouring out from its vents and has been active since 1983.
What are composite volcanoes made of quizlet?
~Composite volcanoes are made up of alternating layers of lava and ash (other volcanoes just consist of lava). CRATER~the viscous (sticky) magma traps hot gases within. A rock plug may be left from previous eruptions.