On what date did the 1980 eruption of Mount St. Helens, in which "Crater Glacier" was formed, occur?
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 state of Washington, United States. The eruption (a VEI 5 event) was the only significant volcanic eruption to occur in the contiguous 48 U.S. states since the 1915 eruption of Lassen Peak in California. However, it has often been declared as the most disastrous volcanic eruption in United States 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 volcano that created a large bulge and a fracture system on the mountain's north slope.
Lava spine A lava spine is a vertically growing monolith of viscous lava that is slowly forced from a volcanic vent, such as those growing on a lava dome (Bates & Jackson, 1987). It may also be considered a kind of dome called a spiny dome (Fink & Anderson, 2000). In February 1983, the dome activity of Mount St. Helens culminated in a spine that reached a height of about 100 ft before collapsing after two weeks, but another lava spine called the Whaleback never collapsed. A diatreme may also be referred to as a lava spine, such as the example of Mount Pelee in 1902.