The Mount St. Helens Event happened on May 18, 1980

Location of the event was:
      Cascade Mountains

In the state of Washington
In the Country of USA

The Abstract for Mount St. Helens:
The first sign of activity at Mount St. Helens in the spring of 1980 was a series of small earthquakes that began on March 16. On May 18, 1980, within 15 to 20 seconds of a magnitude 5.1 earthquake at 8:32 am, the largest landslide in recorded history and a lateral volcanic blast removed 1300 feet of the summit. The October 14, 2004 image shows the area of Mount St. Helen’s removed in the 1980 eruption and a new lava dome in the center of the crater