This is a question about the people below Mt. Rainier.

One thing I wonder about in the case of Mt. Rainier blowing her top is the extent of the lahar flows. I am assuming that it will follow the rivers. And it may depend on how bad it is, and if the eruption and/or the flow is "tilted" in one direction or another.

Looking at a map, the two main rivers (toward populated areas) are the Puyallup, aimed toward Tacoma, and the Nisqually, aimed toward Olympia.

Has anyone run across any info on the likelihood of how far the lahar might travel? Could it make it to the Sound? How fast would it be expected to travel? I understand that they don't really expect lava, due to the multiple glaciers, but the mud and debris would be awful, I would think.

I used to have a marked website for this kind of disaster in this area, but it didn't seem to give much info on what to expect and where to expect it.

I'm not in line with the rivers, but I'd like to know where they would expect the majority of flow. With my luck, I'd probably be on my way south from Seattle.... <img src="/images/graemlins/smirk.gif" alt="" />

Sue

Susan, All that depends on the type of eruption. When Mt. St. Helens erupted in 1980 it blew out the entire north side of the peak along with over a thousand feet of the top. This sent the flow north, down from the mountain. It really didin't matter if you were in a drainage or not, it took out a considerable area north of the mountain. Considering Mt Rainier is about 10 times larger than St. Helens in land mass, a proportional eruption would take out Seattle, the Olympic Peninsula and make Puget sound look like Spirit Lake does today. Let's hope we never see that happen! I have been on both mountains and actually climbed the Forsythe Glacier in 1976 and 79 and you could tell major differences in the mountain from 76 to 79. The Forsythe glacier was where St Helens blew out, next to the "dog's head". I can also tell you in case you haven't experienced it, that Mt Rainier is a very active volcano, near the rim you can see steam rising from fissures and smell the sulfur very strong and that has been that way for a very long time. It is considered much less active than St Helens and not nearly as likely to erupt. The geologists say we used to have a 19 to 20 thousand foot peak here in Arizona, today it is a 12,000 foot cinder covered half bowl. Who knows what Mother Nature is going to do!

The public television station in Seattle has a special on Mt Rainer and it has been shown a number of times here in Oregon. I don't know their station's name but you might check with them. The Oregon station is Oregon Public Broadcasting, OPB. Part of their presentation was outlining the past eruptions and the extent and breath of the lahars. If I remember correctly, they said that thirty minutes was the time estimated between eruption and lahars hitting populated areas.

When Mt St Helens went off, I lost all my rain gutters on my home in Portland, Oregon. The fallout was very heavy and could only be moved so far with high pressure water hoses then you had to resort to machanical means to move it. It is hard to imagine how much energy and force that stuff has when it is flowing especially if it also at elevated temperatures. Now I live slightly east and between Mt Hood and Mt Adams. So I watch the mountains!

There was a presentation about the current state of Mt. St. Helens at today's Communications Academy ( http://www.commacademy.org/ ) One of the handouts was about Mt. Rainier with a map showing potential lahar flows.

The main USGS Cascades site is here:
http://vulcan.wr.usgs.gov/
There are pages about all the major Cascades volcanoes, including hazard reports for each. I don't see the Rainier brochure on the website, but this is the map:
http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Publications/FS065-97/FS065-97_map.pdf

Dave F>

Thank you! The "vulcan" site showed what I wanted to know. It says that I am out of reach of a lahar, but also shows me where I don't want to dawdle around if they're predicting trouble! <img src="/images/graemlins/tongue.gif" alt="" />

Sue

I didn't know what 'lahar' meant.
Nothing in my dictionnaries.
So I went looking on line and found an explanation on this web page.
Some links about Mt Rainier are provided.

looks like some people live dangerously ......

Not to cause worry, but the predictions of danger areas for Mt. St. Helens were very incorrect when it finally blew in 1980 there was far more damage and reach than predicted. Take the time to admire the beauty of those volcanos, never know when they are going to change! I always loved the way Mt. St. Helens looked before the eruption and was saddened by the end result! A beautiful mountain is now a monument to the power of nature and no longer the perfect cone shaped volcano it once was on the horizon! Cheers!

Hey, Frenchy, does that mean you don't want to live directly downhill from an active volcano that has something like 26 glaciers? <img src="/images/graemlins/shocked.gif" alt="" />

I am only 60 miles away from The Mountain as the crow flies, but not in a lahar chute. I suspect that we might get a lot of ash, which would be bad enough, but we wouldn't have to deal with moving concrete!

It would drive me crazy if I lived with Rainier in my back yard.

Sue

..... well... what's 60 miles for the power magnitudes involved in this kind of disasters ?? maybe a big back yard..... you sure could have ashes problems, especially if you're downwind...

Hopefully, I don't leave near vulvanoes, "dead" or alive :
- the nearest dead ones are in the "Massif Central" area, a safe 400 hundred km away ..
- as for the active ones, the "Piton de la Fournaise", on "La R?union" Island, is well west of Madagascar Island.... that's a safer few thousand km from Paris

OTOH, if the Seine river decided to get out of her bed (like a mere century ago), a good third of Paris would be under her waters... <img src="/images/graemlins/confused.gif" alt="" />
and I live at about 150m from the river...
... on the second floor, nevertheless ... it would help a bit .... <img src="/images/graemlins/grin.gif" alt="" />
anyway, I guess a good pair of gum boots are a must for my 72hrs home kit.

Good links defoglesong,

I went to that presentation at the comm academy also.

Lahars and earthquakes are all part of our potential risks living here.