Posted on 07/10/2025 7:34:06 PM PDT by SunkenCiv
Seismologists are closely monitoring Mount Rainier after a swarm of earthquakes struck the Pacific Northwest’s tallest volcano this week. The U.S. Geological Survey (USGS) reports that hundreds of small quakes have occurred since the swarm began, making it the largest such event at the mountain since 2009.
Wes Thelen, a seismologist with the Cascades Volcano Observatory, told FOX 13 Seattle that the quakes began as a concentrated group of seismic events happening in quick succession...
"We had an increase in activity in seismic activity up to about 26 events an hour, which is a pretty good event rate for a quiet volcano," explained Thelen. "Since then, it's tailed off."
He added that while the swarm has calmed slightly, the activity could intensify again.
"We don’t necessarily have a crystal ball to understand what is happening under there," he said...
As of Wednesday morning, seismic instruments had recorded a magnitude 2.3 earthquake among the latest in the sequence. Thelen said the swarm is believed to be caused by hot fluids moving through pre-existing faults beneath the volcano...
Though Rainier last erupted roughly 1,000 years ago, Thelen noted that the volcano is not unusually active when viewed on a longer timescale.
(Excerpt) Read more at fox13seattle.com ...
Thank the Lord. I thought this was the end.
Sure glad I didn’t quit my job.
Holyscroller was a Freeper, and she wrote 4 books on Mt Rainier. (She passed in 2020). Whereas they say Mt Rainier had no “lava flows” they are correct, but Mt Rainier has had a lot of pyroclastic flows, which could be more dangerous than lava. A pyroclastic flow is when superheated steam interacts with dirt to create boiling mud. Evidence suggests that multiple times Rainier has sent this boiling mud down, with walls of it up to 60 feet deep, traveling at 60 mph, and making it as far as Puget Sound at Tacoma. Pyroclastic mud is more dangerous than lava, because it reaches speeds that lava cannot even begin to approach, and flows much further than lava can (evidence of up to 60 miles).
My friends daughter did.
Or a bus plunge in Guatemala last February killed 51. Not as spectacular as Mount St. Helens, though.
We visited in ‘23, and agree that it is a beautiful place. We stayed a couple of nights @ Paradise Lodge. To me, what is appealing about Rainier is that the mountain has no other peaks around to distract from it. It’s very prominent.
Haha, I spent a week in Seattle a few years back. Flew in and out of SeaTac, went up in the Space Needle, Gig Harbor, Bainbridge Island, etc...all the sites... um, in a constant misty rain. Didn’t see Mt. Ranier once. Thought my last chance was going to be flying south and east out of the airport, had a window seat on the right side of the plane where Ranier would be as the plane banked eastward before the mountain and then... hit the cloud ceiling about 1000 feet in the air and didn’t see the ground until we were over the Rockies
I knew what a pyroclastic flow was (the Indian paint pot in Yellowstone being of such a material), but was unaware of the particulars re Mt. Rainier. Thank you!
Great....just great. Will be at Civil Air Patrol NCSA with my kids, 14 and 12 in two weeks for two weeks.
Also a threat from a Mt. Rainier eruption are lahars (massive mudslides). These will be triggered upon eruption by the melting of the massive snow pack on Rainier that instantaneously becomes billions of gallons of water that will destabilize mountainsides and mix with dirt creating huge mudslides traveling at the speed of freight trains. Communities at the foot of the mountain could be hit within an hour of the eruption by lahars that scour the ground and leave nothing in their wake. Historically, some of these lahars from Mt. Rainier eruptions have reached the Puget Sound.
A worst case scenario of a major eruption of Mt. Rainier could make the 1980 eruption of Mt. St. Helens look like a grade school science project in comparison.
I flew up from Santa Barbara. Saw the Southern Cascades. St Helens blew me away. Half the mountain is still gone! Driving up to Ranier is awesome. So gigantic over the surrounding terrain.
I went in June. I was tramping around in the snow in my shorts. The air was so crisp. I’d love to take my family.
Lahar and Pyroclastic Flow are synonyms
As I understand it, the are not the same. Similar but with differences. A pyroclastic flow is volcanic debris propelled by gases while a lahar is volcanic debris propelled by water. A pyroclastic flow is primarily composed of super-heated volcanic ash emitted at the eruption while a lahar is basically a mudslide comprised of ash, dirt, and water which begins to be created at the eruption but whose effects come later after the eruption. Pyroclastic flows kill through scorching or by toxic gases. Lahars kill by crushing those unable to get away from the cement-like slurry.
“they” not the in the first line.
My understanding is that the term pyroclastic refers to the mud. The mud is created by superheated gases (not necessarily ash) that is expelled in the eruption, which near instantaneously melts the snow and ice on the mountain that it comes in contact with, and mixes it with dirt as well as rock, trees, boulders and anything else in the eruption area. This becomes a very hot, viscous mud on an unstable hillside with the force of the blast propelling it.
Yes, there are gasses and high heat initially (and quite frankly, if the gasses and heat did not get you, the blast would), but the fine line you are differentiating is between the initial stage at eruption and the end stage (maybe 60 miles away) of the exact same flow of mud. Of course the heat will be lower downstream, and many of the heavier solids (boulders) will settle before making it to the end.
Lahars may crush, but they kill by consuming everything in their path. Around Mt Rainier, there are many examples of forests with nothing but dead treetops. The trees were not crushed, they survived the mud flowing around them, but died because unlike water, the mud never recedes and their roots are now 50-100 feet below the surface. A person caught in a lahar or pyroclastic flow (again, I hold they are the same thing) would be in a situation akin to trying to swim out of a very fast moving river of quicksand.
Note, as when St Helens erupted, you do see rivers overflowing their banks and carrying entire forests downstream ... but those are NOT Lahars. Those are caused by lakes being emptied and some melting of snow/ice and of course rain. The recent floods in TX were certainly not lahars, they were flooded rivers. I would challenge you to find a Lahar that did not start as a pyroclastic flow.
Final note. If you look up the term “Lahar”, it is a violent mud/debris flow composed of a slurry of pyroclastic material, rocky debris, and water.
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