While Hawaii and Alaska are the two states most often associated with volcanic eruptions, 11 of the 18 very highest threat volcanoes on U.S. soil are located in the Western United States - 4 in Washington, 4 in Oregon & 3 in California. (note: Yellowstone is ranked 21st).
In addition, 39 volcanoes are listed as posing a `high threat', and 49 are ranked as a `moderate' threat. These are not predictions of which volcanoes are apt to blow next, as explained below:
The updated national volcanic threat assessment presented here is not a forecast or indication of which volcanoes are most likely to erupt next. Rather, it is an indicator of the potential severity of impacts that may result from future eruptions at any given volcano. As such, the assessment can be used to help guide and prioritize volcano research, hazard assessment, emergency planning and preparation, and monitoring efforts by Federal, state, and local government.
We've discussed eruptive hazards before - both internationally (see here, here, and here), and domestically (see Washington State: Volcano Awareness Month). While earthquake damage is generally localized, volcanic eruptions (and tsunamis) can affect property and populations thousands of miles away.
- In 2010 airline traffic in Europe was disrupted by the eruption of Iceland's Eyjafjallajökull volcano (see study The vulnerability of the European air traffic network to spatial hazards), halting many flights for nearly a week.
- When Mount Pinatubo erupted in the Philippines in 1991, within a year its aerosol cloud had dispersed around the globe, resulting in `an overall cooling of perhaps as large as -0.4°C over large parts of the Earth in 1992-93’ (see USGS The Atmospheric Impact of the 1991 Mount Pinatubo Eruption).
- In 1783 the Craters of Laki in Iceland erupted and over the next 8 months spewed clouds of clouds of deadly hydrofluoric acid & Sulphur Dioxide, killing over half of Iceland’s livestock and roughly 25% of their human population. These noxious clouds drifted over Europe, and resulted in widespread crop failures and thousands of deaths from direct exposure to these fumes (see 2012 UK: Civil Threat Risk Assessment)
All of which means you don't have to live in the shadow of one of these slumbering giants to be impacted by an eruption.
The 40 page 2018 update to the U.S. Geological Survey national volcanic threat assessment and summary are available at this USGS link.
The Pacific Northwest is particularly ripe for a large seismic event, tsunami, and/or volcanic eruption. A topic we've explored previously in:
OSU: Pragmatic Action - Not Fatalism - In Order To Survive The `Big One’
NPM13: The USGS West Coast Tsunami Scenario Report
Today I'd also like to call your attention to a recent (August 2018) TEDxPortland talk, presented by Steven Eberlein, on Why we do not prepare for earthquakes.
While the advice and information presented in this entertaining 10-minute talk should be of value to everyone, if you live anywhere near the Pacific Northwest, it should be at the very top of your viewing list.