On May 8, 1980, Mount St. Helens erupted. This was after a 5.1 earthquake and it was a big event.
There had been small earthquakes before that and the United States Geology Service warned that the Mount St. Helens volcano could erupt.
The United States Geology Service, USGS, and the Forest Service of the United States Department of Agriculture, fs, usda took pictures before and after the eruption.

Let’s start with the maps.

US maps of the states  by, EPA.  Washington is way up on the left and it is gray.

Cascades mountain range  by, Shannon, Wikipedia Commons

This shows layers of a volcano  by, USGS.

This is a before picture  by, fs, usda.

This is the eruption  by, USGS.

This is the plume  by, Mike Doukas, USGS.

This picture was take before the eruption  by, US Forest Service.

This is the same place after the eruption  by,  fs, usda.