Mount St. Helens 1980 Eruption

On May 18, 1980, Mount St. Helens erupted after 123 years of hibernation.

Magma pushed the north face outward nearly 500 feet. Geologists watched this cryptodome swell for weeks. Geologists prefer their mountains less inflatable.

It briefly passed the speed of sound.

At 8:32 a.m., a magnitude 5.1 earthquake triggered the largest subaerial landslide in recorded history.

Exposed magma exploded laterally at 670 mph. Barry Voight sent his report on May 1.

An eruption column rose 80,000 feet into the atmosphere. Ash fell across 11 U.S. states and several Canadian provinces.

About 57 people died, including volcanologist David A. Johnston. Burlington Northern Railroad owned the summit then. The summit is now publicly owned.

Four decades later, floating log mats still drift on Spirit Lake, changing position with the wind. The trees are slowly becoming petrified.