And then there's the Cascade Volcano arc, many of which I have climbed and can confirm are 'active'. For example, you can see 'bubbling goo' at the Devil's Kitchen near the summit of Mt Hood, and wisps of steam emerging from many of the others. And Mt St Helen's blew up in 1980.
The lahar threat to Seattle from Mt Rainier is particulalry serious, apparently, and there is a similar threat to the Sea to Sky/ Vancouver area from Mt Garibaldi. There is geologic evidence that some of these volcanoes have erupted over a series of years in the past.
From the summit of Mt Douglas in Victoria you have direct line of sight to Mt Baker and Mt Rainier, amongst others. The blast from a big eruption, like Mt St Helens, would hit us pretty full on.
Cascade Volcanoes
The
Cascade Volcanoes (also known as the
Cascade Volcanic Arc or the
Cascade Arc) are a number of
volcanoes in a
volcanic arc in western
North America, extending from southwestern
British Columbia through
Washington and
Oregon to
Northern California, a distance of well over 700 miles (1,100 km). The arc formed due to
subduction along the
Cascadia subduction zone. Although taking its name from the
Cascade Range, this term is a geologic grouping rather than a geographic one, and the Cascade Volcanoes extend north into the
Coast Mountains, past the
Fraser River which is the northward limit of the Cascade Range proper.
Some of the major
cities along the length of the arc include
Portland,
Seattle, and
Vancouver, and the population in the region exceeds 10 million. All could be potentially affected by volcanic activity and great subduction-zone
earthquakes along the arc. Because the population of the
Pacific Northwest is rapidly increasing, the Cascade volcanoes are some of the most dangerous, due to their eruptive history and potential for future eruptions, and because they are underlain by weak, hydrothermally altered volcanic rocks that are susceptible to failure. Consequently,
Mount Rainier is one of the
Decade Volcanoes identified by the
International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being worthy of particular study, due to the danger it poses to
Seattle and
Tacoma. Many large, long-runout landslides originating on Cascade volcanoes have engulfed valleys tens of kilometers from their sources, and some of the areas affected now support large populations.
en.wikipedia.org