Volcanic Activity

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Mercer Slough Oct. 2017.JPG

A volcano is a vent in the earth’s crust through which lava, rock fragments, gases, and/or ash can be ejected from the earth’s molten core. Washington State is home to five major active volcanoes: Mount Rainier, Mount Baker, Mount St. Helens, Mount Adams, and Glacier Peak. Although Bellevue is not situated directly under or within the path of a volcano, the City may experience hazards such as ashfall and acid rain. City operations may or may not be curtailed by a volcanic eruption because services and infrastructure are interdependent within the region and other towns, cities, and counties may be requiring high levels of assistance.

The impacts to Bellevue depends on the magnitude of the eruption and wind patterns. If the eruption produced significant amounts of ash coupled with prime climatic conditions which could transport the ash to Bellevue, the City’s normal operations could be stymied. Due to the prevailing wind patterns within the region, the ash would probably blow away from Bellevue.

Ash can collapse roofs, destroy engines, endanger utility networks, create hazardous road conditions, and clog water, air, and filtration systems. Ashfall of more than 1 centimeter has the ability to disrupt traffic by closing roads.

Casualties are likely to be minimal compared to the economic impacts. The most deadly hazards such as lahars, flashfloods, landslides and rockflows will not impact Bellevue. Hazards such as ashfall and acid rain may impact Bellevue upon specific climatic conditions. Because geologists can generally detect conditions that precede eruptions, the region may have time to prepare. 

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