Mount St. Helen: During 1980 eruption

Photo: Harry Glicken/U.S. Geological Survey

More than three and a half decades later, the 1980 eruption of Mount St. Helens remains the United State's deadliest and most economically devastating volcanic event.

In addition to causing more than $1 billion in damages, the eruption killed 57 people, including David A. Johnston (below at right), a 30-year-old volcanologist working for the United State Geological Survey.

David Johnston looking through a correlation spectrometerJohnston, who was monitoring the mountain from an outpost 6 miles away, witnessed the 5.1-magnitude earthquake that caused the collapse of the volcano's north slope. The resulting landslide remains the largest in recorded history. Before Johnston was swept away by the subsequent lateral blast, he sent out one last radio transmission: "Vancouver! Vancouver! This is it!"

In the few months prior to the big event, scientists like Johnston had observed earthquake swarms, phreatic eruptions, the development of a cryptodome and other major geological changes. Since this was the first recorded volcanic activity on the mountain since its last eruption in the 1850s, scientists, photographers and other curious observers flocked to the mountain every day to watch the fascinating changes.

Gary Rosenquist, a photographer who was camped out just 11 miles away from the blast zone, was situated just far enough away to safely witness and document the violent eruption. As seen in the video below, Rosenquist's images — taken in rapid succession over a span of just less than a minute — show the fascinating sequence in which the initial debris avalanche gave way to dense lateral blast clouds:

The area surrounding Mount St. Helens is still in the process of recovering from this fateful day, but thanks the resiliency and ever-changing nature of our planet, it's already well on its way.

While it's not quite the forest it once was yet, take a look at how this volcanic monument has transformed over the years, from 1980 to today:

May 17, 1980 — one day before the eruption

Mount St. Helen: Before 1980 eruption

Photo: Harry Glicken/U.S. Geological Survey

Captured just hours before the eruption, this serene image was taken at the site of Johnston's observation camp, where he later died. The spot was later named "Johnston's Ridge" in his memory, and it is now the site of an observatory.

Sept. 10, 1980 — 4 months after the eruption

Mount St. Helen: Immediately after the 1980 eruption

Photo: Harry Glicken/U.S. Geological Survey

Plumes of smoke emerge from the horseshoe-shaped crater of a drastically altered Mount St. Helens.

Mount St. Helens, today

Mount St. Helen today

Photo: tusharkoley/Shutterstock

For many years, the land surrounding the volcano remained a seemingly barren wasteland, but before long, inklings of greenery began making its way back into the picture.

Continue below to see more examples of how new plant growth is manifesting on this volcanic landscape:

Mount St. Helen: New growth

Photo: Bridget Calip/Shutterstock

New green growth emerges from the ruins of dead snags destroyed by the eruption.

Mount St. Helen: Tree stump

Photo: Bill Perry/Shutterstock

Wildflowers and green shrubs frame an ashen tree stump.

Mount St. Helen: Winding road

Photo: Christopher Boswell/Shutterstock

A winding road snakes around the recoverining slopes around Mount St. Helens.

Mount St. Helen: Foxglove

Photo: tusharkoley/Shutterstock

Foxgloves bloom on a grassy slope as Mount St. Helens looms in the distance.

Mount St. Helen: Spirit Lake in 2012

Photo: Stephan Schulz

Dead tree trunks float on the surface of Spirit Lake near Mount St. Helens.

Mount St. Helen: Wildflowers

Photo: Ronald Sherwood/Shutterstock

Wildflowers thrive near the blast zone of Mount St. Helens.

Mount St. Helen: Dead trees

Photo: Christopher Boswell/Shutterstock

Snags tower above a road running through the blast zone of Mount St. Helens.

Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.