Where was the most recent volcanic eruption in the contiguous states of the USA?
1980 eruption of Mount St. Helens 1980 eruption of Mount St. Helens On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the U.S. state of Washington. The eruption (a VEI 5 event) was the most significant volcanic eruption to occur in the contiguous 48 U.S. states since the much smaller 1915 eruption of Lassen Peak in California. It has often been declared as the most disastrous volcanic eruption in U.S. history. The eruption was preceded by a two-month series of earthquakes and steam-venting episodes, caused by an injection of magma at shallow depth below the
Volcanic history of the Northern Cordilleran Volcanic Province likely formed between nine thousand and a few hundred years ago. At least five volcanoes sent lava down the Iskut and Unuk River valleys and their tributaries. The other three volcanoes were formed when glacial ice existed adjacent to the associated volcanic vents, creating scoria, pillow lava and hyaloclastite breccia. Volcanism in the Iskut River area has created at least ten lava flows and Lava Fork at least three. The most recent eruption of the Iskut-Unuk River Cones at The Volcano (also called Lava Fork volcano) in 1904 is also the most recent volcanic eruption in Canada. Immediately north of