Three Sisters Volcano

Volcano Characteristics

• Type of volcano : Stratovolcano
• Formed by different types of magma
• North sister - Andesitic, Basalt
• Middle and South Sister - Rhyolite, Dacite, and andesite
• Viscosity : Lava will form dome, or flow of laval (10km).

Volcano Vents

• Lie between dense and broad areas.
• Mafic vents that are scattered around.
• Three peaks : North, South, and Middle Sister.

History of Eruptions

• Location : Oregon, U.S.
• Volcano is currently not active, but a swelling started to form beginning of 1997.
• Past eruptions : small and single eruptions with low shield and small strato cones.

Past eruptions of Three Sisters Volcano

Past eruption of Three Sisters continued...

Features produced in eruptions

• Lahar : past explosive eruptions created lahars, which traveled tens of km away.
• Pyroclastic flow : Two ways with three sister volcano - collapse of tephra flume, or collapse of steep flow lava
• Due to the pyroclastic flow it resulted in basaltic and basaltic andesite to flow. This also resulted in tephra deposits (13 m). Some were even found in northern California.

Human Impacts

• Located near central Oregon with an increasing population, which can be hazardous towards the growing population.
• People who live near Three Sisters volcano live their lives regularly. Unlike Japan, they do not conduct drills. It is due the volcano being inactive for several years, and there are no signs of it being active in the near future.

Picture of the map where Three Sisters Volcano can be found.

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Reducing Volcanic Eruptions

• Scientists observe ground movements, earthquakes, remote satellite, and volcanic gas.
• Cameras are setup on the south, middle and the north sister to see if there are differences each day. They also use things such as earthquake and lahars detectors, and they use thermal imaging, which is used from the cameras.

Topographic of Three Sisters

Works Cited