The west coast of the U.S. is not only characterized by earthquakes and related myths, but also by volcanoes and also these natural phenomena became incorporated in supernatural stories.
Many mountains of the Cascade Range were feared by local tribes. The Canadian artist Paul Kane (1810-1871), who visited Mount St. Helens, wanted to climb the mountain, but was unable to find any guide willing to show him an access to the area, as
"this mountain has never been visited by either whites or Indians; the latter assert that it is inhabited by a race of beings of a different species, who are cannibals, and whom they hold in great dread."
Other stories recorded by ethnologists tell of strange encounters, as "sometimes people would hear three whistles, and soon stones would begin to hit their lodges. Then they knew that the giants were coming."
Also Spirit Lake was named after an old tradition involving evil beings - according to this myth the salmons found in the lake are cursed people - and therefore a place to be avoided.
Maybe these legends involving areas not to be visited or settled were influenced by the observed devastating effects of ancient volcanic eruptions.
The Klamath People of Oregon tell the tale of the battle of Chief of Above World - called Skell- with Chief of Below World - called Llao. For many days their fight raged over the land, the two adversaries' hurled rocks and flames at each other and soon darkness covered the land. To better see his enemy Llao decided to climb on the highest mountain he could find - the ancient volcano Mount Mazama - but as soon as he reached the peak the mountain collapsed with terrible thunder, burying him alive. The surviving rim of Mount Mazama is today better known as Crater Lake.
An eruption in 1800 at Mount St. Helens, known by the locals as Tah-one-lat-clah, the Fire-Mountain, caused great concern, the Spokane Indians of eastern Washington thought that "the world was falling to pieces" and the Kalispel of northern Idaho, who remember a rain of "cinders and fire", believed "that the sun had burnt up, and that there was an end of all things."
According to one legend once Mount Baker, known previously as Komo Kulshan, got so mad that a big piece fell off and slid way down the mountain, causing a big fire and a loud thunder.
Mount Rainier, or Tacobud, also one day take a breath so deep that she burst her blood vessels and rivers of blood (lava?) flowed down her sides. Additionally the volcano was inhabited by a terrible, flood causing monster, which however was finally defeated by a party of mighty warriors.
Mount Hood, or Wyeast, was also a mountain haunted by evil spirits who "became so angry that they threw out fire and smoke and streams of hot rocks.." and caused "rivers of liquid rock [that] ran toward the sea, killing all growing things and forcing the Indians to move far away". Unfortunately at the time a great chief, sacrifying his life during an epic battle with the demons, was only capable to entrap them, so it is still possible that one day they will return and Mount Hood erupt again.
Fig.1. Cascades eruptions during the past 4.000 years, compiled by the U.S.G.S. (it is believed that the use of low-resolution images qualifies as fair use under United States copyright law).
Even if some stories resemble the description of an eruption followed by lava and pyroclastic flows and ash clouds, caution must be adopted to ascribe every myth to a specific and real eruption. Many volcanoes erupted thousands of years ago (like Mount Baker, 6.000 years, Mount Rainier, 2.000 years or Mount Mazama, 6.000 years) and it is hard to imagine that oral traditions were passed unmodified trough so many generations and changing cultures in such vast periods of time.
However it is still possible that some legends were really inspired by relatively recent eruption, like Mount Hood or Mount St. Helens, and that these myths were subsequently adopted to other, maybe similar looking, mountains.
CASHMAN, K.V. & CRONIN, S.J. (2008): Welcoming a monster to the world: Myths, oral tradition, and modern societal response to volcanic disasters. Journal of Volcanology and Geothermal Research 176: 407-418
VITALIANO, D.B. (2007): Geomythology: geological origins of myths and legends. In Piccardi, L. & Masse, W.B: (eds): Myth and Geology. Geological Society, London, Special Publications, 273: 1-7