![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi2eH0MY51rjID0kICgCx06rlzH09vhHG2bNmoTTMvCWMNOIEqQjl24FUodTctoXj5ZLg0e93lOyiuJs10yGU-mjPVHKQ52EIv1y-d_cJ-D-lX06z3kX2x41MGYsOJKZcMQFCMlYY5UHqnikVD8PX0MBYA-66apynG13CCdjoVLtkgOzoKAvR6C8xRgdfQn/w426-h640/Photograph%20of%20the%20eruption%20column,%20May%2018,%201980,%20taken%20by%20Austin%20Post.jpg) |
Photograph of the eruption column, May 18, 1980, taken by Austin Post. |
On May 18, 1980, at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens.
The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano. Thirteen-hundred feet (400 meters) of the peak collapsed or blew outwards. As a result, 24 square miles (62 square kilometers) of valley was filled by a debris avalanche, 250 square miles (650 square kilometers) of recreation, timber, and private lands were damaged by a lateral blast, and an estimated 200 million cubic yards (150 million cubic meters) of material was deposited directly by lahars (volcanic mudflows) into the river channels. Fifty-seven people were killed or are still missing.
USGS Photograph taken on May 18, 1980, by Austin Post.
* Mount St. Helens in Skamania County, Washington, United States.