Two-thirds of a cubic mile of rock and ice thunders down the mountain at 150 miles per hour.
And then the mountain explodes.
With the pressure lid removed, superheated magma and gas erupt sideways—not up, but horizontally—in a lateral blast no one had fully anticipated.
A pyroclastic density current—a hellish hurricane of rock, ash, and gas at 680°F—screams northward at 300 miles per hour. Faster than a commercial jet.
Straight toward David Johnston.
He has seconds. Maybe fifteen.
He grabs the radio. His training takes over. His voice is calm, urgent, clear:
"Vancouver! Vancouver! This is it!"
Then the mountain hits him.
The blast wave strikes Coldwater II with the force of multiple nuclear bombs. Trees snap like toothpicks. Boulders the size of trucks are flung miles through the air. The landscape is scoured to bedrock.
David Johnston, his trailer, his equipment—everything—simply ceases to exist.
Fifteen seconds after his final transmission, the observation post is gone. Obliterated. His body was never found. The eruption erased him from the Earth.

48°52.6′S 123°23.6′W