Large rock avalanche on Mt. Rainier caught on camera

I know. The entire west face of the mountain is ‘geologically rotten’. So much acidic gas has seeped up from below that the rock under the ice is the geologic equivalent of soft cheese. The only thing that holds Rainier together is the sheer weight of the ice on top. One geologist has suggested that if a really good quake ever hit the right spot beneath the mountain, a good chunk of the west face would slide off and down the valleys.

The Green, White, Puyallup, and Nisqually rivers are fed off Rainier. ALL those valleys are populated, with the Puyallup River having the greatest population density.

It’s said that if a big lahar were to happen, the entire downtown area of Puyallup would be buried in anywhere from 10-30 feet of mud and debris. Other smaller towns like Orting, Sumner, and Carbonado would be erased from the map.

If the lahar warning sirens ever really went off, the population would have anywhere from 20-30 minutes to get to higher ground. Considering how traffic normally moves around here...I shudder to think what it would look like.

You’ve restated, quite clearly, all the things my geologist ex-wife told me about Mt. Rainier. I just hope it doesn’t happen soon.

On another note, that California-made Vitamin R is quite tasty !

I don’t know if you believe in things like prophecies — I know many don’t — but I have heard one that said that there was going to be, at some time in the future, a major eruption with some volcano here in the US

That's not a prophecy, that's a a statement of fact without particular meaning.

It's like saying that "at some time in the future, a major tornado with some storm here in the US."

First, the relatively small rocks you refer to ... some of those would be the size of your car. This mountain is 14,410 feet high, and the picture is probably being taken from around the 7,000 ft level.

I cant be sure exactly where they are, but my guess is that this was actually part of the Ingraham Glacier calving over the rock face that separates it from the Cowlitz Glacier. As the tons of ice cascades down the rock face, (which I think is mostly volcanic lava at that point, not the harder Granite you find lower), it easily smashes it to pieces. The avalanche has mass, speed and trajectory behind it, and when it gets to another rock field (which is mostly debris from previous slides, it simply pushes it much the same way a shop broom pushes dirt around. The white cloud is mostly ice.

Rocks on volcanoes fragments easily. Even if it is a relatively hard rock like granite, it is exposed to millennia of weathering where water gets into tiny cracks, freezes (expands) then when it thaws the crack is bigger so more water can get in for the next cycle. Basically, the same reason that potholes form on roads.

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