Discover and read the best of Twitter Threads about #MountStHelens

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At 8:32 am Pacific time, May 18, 1980, it happened.

#MountStHelens exploded, producing the largest landslide ever recorded, sending a tower of rock and ash 19 km into the stratosphere, and killing 57.

I've added the Empire State Building to this image for scale.

A thread:
A shallow earthquake caused the entire northern flank of the volcano to slide. The reduced pressure allowed a huge "cryptodome" of hot, pressurised magma inside the volcano to explode—creating a lateral blast that flattened trees for tens of kilometres.
The eruption blasted fragments of volcanic rock and glass, powered by superheated gases, into a huge column (a Plinian eruption) that reached 19 km into the atmosphere; ash blanketed towns 400 km, and some even landed in the Great Plains, 1,500 km away.
Read 8 tweets
Exactly #40YearsAgo Doug Geisler was asleep atop Manastash Ridge Observatory. An astronomy grad student, he’d just logged his first excellent night at the telescope for his PhD thesis.

He was the only person on the summit, ~90 miles from #MountStHelens...

Around this time #40YearsAgo Doug woke up briefly at Manastash Ridge, convinced he’d heard a low boom or distant rumble.

Tired after a night of observing billion-year-old stars, he went back to sleep.

Years later, he told me he dreamed about the end of the world. #MSH40
(it’s hard to say exactly what he heard - it could have been the initial 26 megaton blast or the deafening secondary explosion from the volcano’s superheated material instantly vaporizing nearby bodies of water into steam)

Anyway, back to sleep for the tired astronomer...
Read 17 tweets

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