The May 22, 1915, explosive eruption of Lassen Peak, California, blasted rock fragments and pumice high into the air and rained fine volcanic ash as far away as Winnemucca, Nevada, 200 miles to the east. In this photograph taken from near the town of Red Bluff, 40 miles west of the volcano, the huge column of volcanic ash and gas produced by the eruption rises to a height of more than 30,000 feet. (Photograph taken by R.E. Stinson; courtesy of the National Park Service.)We cannot seperate Hawaii from volcanoes. All Hawaiian islands were formed from volcanic activities initiated at undersea magma sources called hotspots. The islands still have several active volcanoes. California has also several active volcanoes. Long before the recent activity of Mount St. Helens, a series of spectacular eruptions from Lassen Peak between 1914 and 1917 demonstrated the explosive potential of Cascade volcanoes. Small phreatic explosions began on May 30, 1914, and were followed during the next 12 months by more than 150 explosions that sent clouds of ash as high as 3 kilometers above the peak. The activity changed character in May 1915, when a lava flow was observed in the summit crater. A deep red glow from the hot lava was visible at night 34 kilometers away. On May 19, an avalanche of hot rocks from the lava spilled onto snow and triggered a lahar that extended more than 15 kilometers from the volcano. We cannot 100 percent ensure the possibility of volcanoes in California.
Source: http://pubs.usgs.gov/gip/volcus/ustext.html
img -> pubs.usgs.gov/fs/1998/fs173-98/
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