Anniversary of Mt St Helens
On May 18, 1980, a second earthquake, of magnitude 5.1, triggered a massive collapse of the north face of the mountain. It was the largest known debris avalanche in recorded history. The magma in St. Helens burst forth into a large-scale pyroclastic flow that flattened vegetation and buildings over 230 square miles (600 km2).
Yeah, I remember that well! I hadn’t remembered the details, though.
The eruption killed 57 people, nearly 7,000 big game animals (deer, elk, and bear), and an estimated 12 million fish from a hatchery. It destroyed or extensively damaged over 200 homes, 185 miles (298 km) of highway and 15 miles (24 km) of railways.
83-year-old Harry R. Truman, who had lived near the mountain for 54 years, became famous when he decided not to evacuate before the impending eruption, despite repeated pleas by local authorities. His body was never found after the eruption.
Another victim of the eruption was 30-year-old volcanologist David A. Johnston, who was stationed on the nearby Coldwater Ridge. Moments before his position was hit by the pyroclastic flow, Johnston radioed his famous last words: “Vancouver! Vancouver! This is it!” Johnston’s body was never found.
I remember the images of the ash piling up, and the devastation around the volcano.
Here’s a video of today’s important ongoing volcanic event: one of the Kilauea eruptions
Around 2,000 people have evacuated the surrounding area. Lava leaking from the fissures has destroyed at least 26 homes and 10 other structures, according to the Associated Press.
Pretty alarming. Good luck to everyone near the Hawaiian volcanoes!
Here’s a post from The Washington Post about the Yellowstone supervolcano:
Yellowstone is capable of eruptions thousands of times more violent than the Mount St. Helens eruption of 1980. The northern Rockies would be buried in multiple feet of ash. Ash would rain on almost everyone in the United States. It’d be a bad day.
Yeesh. It certainly would.
Intellectual humility is called for here: No one can say with great confidence how much magma it takes to trigger a caldera-forming eruption.
There’s the most important sentence in the article. What the past few years have shown us for sure — drawing on astronomical discoveries as well as terrestrial — is that we don’t understand as much about planetary science as we thought.
This eruption isn’t what I would pick if I wanted to write a post-apocalyptic novel — partly because it’s been done. Mike Mullen did it in his Ashfall trilogy (has anybody read that? I wonder if I should try it?). And Harry Turtledove did it in his imaginatively titled Supervolcano Eruption. (I’m not likely to try that one as I don’t really like Turtledove’s writing.)
Anyway, I’d rather use a major earthquake along the Cascadia fault.
No shortage of geological disasters that are not only possible, but certain to happen eventually …
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