Mount St. Helens erupted on May 18, 1980, killing 57 people and causing more than a billion dollars in damage. Ash blanketed the Pacific Northwest and stretched into 11 states and Canada.

WATCH: Man spared by Mount St. Helens says 'part of me died up there'

Carmen R. Andrews shared these incredible photos from the eruption and describes the experience:

"When I was 14 years old, my classmates from Garfield High School and I went on a biology field trip to see the diatomaceous earth outside of Vantage, Washington. We actually heard the eruption as we were packing up to go home but it wasn't loud enough to really register as something big at the time and it was only later that we realized that we actually heard it when the volcano erupted."

Photos: Mount St. Helens ash cloud - yes, they're real

Where were you when the mountain erupted? Share your memories and photos on the KING 5 Facebook page.

Also see: Never-before-published photos of the Mount St. Helens eruption