The familiar snow-clad peaks of the Cascade selection are part of a 1,300 kilometres (800 mi) chain the volcanoes, which extends from northern California to southerly British Columbia. The volcanoes room the an outcome of the slow-moving slide of dense oceanic crust as it sink beneath phibìc America (subduction), i m sorry releases water and melts overlying rock. This wealthy volcanic zone consists of the famous landmark volcanoes and approximately 2,900 other well-known volcanic attributes ranging indigenous small cinder cones to an extensive shield volcanoes.

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Eruptions in the Cascade selection during the previous 4000 years. GIP 63 (Public domain.)

Cascade volcanoes have erupted in the recent past and also will erupt again.

The time between eruptions is usually measured in years or centuries, so eruptions space not a component of our day-to-day experience. However, current eruptions at Mount St. Helens vividly demonstrate the power and also impacts that Cascade volcanoes can unleash as soon as they perform erupt.

During the past 4,000 years, periods of eruptive activity at miscellaneous Cascade volcanoes have lasted because that a couple of to tens of years per century. Locate the volcano closest come you by visiting the map on our home page. Seven Cascade volcanoes have actually erupted because the beginning of the eighteenth century. Few of those eruptions would have caused substantial property damage, financial disruption, and loss that life if they had arisen today without warning:

Population growth method increase in risk.

As populace increases in the Pacific Northwest, locations near the volcanoes space becoming occurred and more people and property room at risk. The principal dangers to world in the Pacific Northwest room from lahars and ash fall. Lahars(volcanic mudflows) can ruin buildings and infrastructure. Eruptions that include volcanic ash deserve to be especially dangerous because that aircraft, also at long distances from the volcano, due to the fact that volcanic ash have the right to clog and also shut under their engines. To find out more, read about volcanic dangers on this website.

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National volcanic threat assessment identifies dangers to inhabited areas.

Volcanic danger is the combination of risks (the danger or devastating natural phenomena created by a volcano) and exposure (the people and property at hazard from the volcanic phenomena). Based ~ above eruption background and street to population centers, a 2018 volcanic threat assessment designated nine volcanoes in Washington and also Oregon with a "high" or "very high" rating. Really High Threat: Crater Lake, Glacier Peak, mountain Baker, mount Hood, mount Rainier, mount St. Helens, Newberry, three Sisters. HIGH: mountain Adams. 

Download the 2018 upgrade to the U.S. Geology Survey nationwide volcanic risk assessment.