What Can Idaho Learn from the Mudslide in Oso, WASHINGTON?

[ScottStielow]

When i was stationed in Everett WA in the Navy back in 1998-2000. The Wife and i use to take Drives up through Oso. Loved the beauty of the area. Oso was on my short list of retriement locations. Prayers have been sent all week, to all the families involved in the mudslide in Oso.
Scott

PS. An added bit of information. Back in 1999. There was a mention of possible mud slides in the furture in the area around Oso.

[Old Monkey]

Originally Posted by banjomike

I'm no expert, but I've read some stuff about our geology.
The last ice age's height was about 20,000 years ago, and it was different than the earlier ones. There was still a hugely thick mantle of ice that covered most of Canada when it happened, but in our area, the ice sheet, called the Cordillera mantle, lay only in N. Idaho. The mountains all formed massive glaciers during this period, and some of the glaciers merged into the huge ice mantle.

Idaho was higher than it's neighboring states of Montana and Washington. The huge Cordillera mantle extended in a big lobe inside Washington from Canada to halfway down to Mt. St. Helen's. As this mantle receded, it left mountainous piles of loose rocks and other debris at it's leading edge. Eventually, trees and grasses stabilized these mountains, and their weight compressed them into more solid masses, but none are solid rock as the Rockies are. Most of the upper Cascade range is like this.

Those mountains essentially have no solid core holding them up. So when there is heavy moisture, they can cut loose as slide.

As the glaciers slowly melted, they formed Lake C d'Alene and the others but mostly didn't have glaciers that merged into the ice mantle. But just over on the Montana side, the mantle extended down as far as the Flathead Lake/Kalispell area, and many mountain glaciers merged into the mantle there. They created Lake Missoula, which flooded several times and washed most of interior Washington down to the Pacific, and later, created the Columbia Gorge.

Further south east, along the northern slope of the Rockies, only mountain glaciation occurred, and so only the mountainous areas had glaciers. The rest of southern Idaho, which is higher than the north, escaped the last ice age, but the mountain glaciers left areas at their bases with unstable soil full of rocks.

Idaho escaped most of the ice mantle, but we still lie on top of a couple of big fault lines, and one has a hot spot like Hawaii- the Yellowstone Park area is where the hot spot is now, but around the same time as the last ice age, it burned it's way upward from Nevada/California and crossed Idaho in what is now the Arco desert. The hot spot is like a cutting torch working it's way through thick steel plate; small in area but very intense. It's slowly working it's way north east.

The Island Park area was once an enormous volcano that was about 9,000 feet higher than the Snake River plain. It was so large that when it blew, there were many major eruptions at once, causing it to fall into itself and creating a caldera- a volcano that lost over half of it's height. The rest went airborne and formed the volcanic soil that grows the best potatoes in the nation. Yellowstone Lake lies at the bottom of another caldera that is much larger but not as high.

MSR- Hwy. 26, the one that follows the Snake River canyon into Jackson Hole, is prone to rock slides, not mud slides. That area had mountain glaciers that chewed away solid rock, but those glaciers never moved a big bunch of dirt and loose rocky soil ahead of them as what happened in Washington. Some areas are more prone to mudslides, but we would have to get heavy coastal rainfall for many years to start them sliding. It's more likely an earthquake would be a trigger.

The slide ares along that road are well mapped and well known. The worst have steel fences to prevent errant boulders from landing on the roadway, but one big boulder can wipe out any fence. Much of the canyon is what's called 'rotten rock'- that's rock that has endured a lot of cracking due to ice expansion and contraction during winter. This can cause little rocks to peel off and fall, or part of a mountain to come loose and fall at any time.

Nature can move things very fast. Our problem as humans is: if it hasn't happened yesterday, we all think every big natural event happened ages ago. All one usually has to do is look up. If a nearby ridge looks like something came loose and slid down, there's a good chance it will slide again.

Cogent explanation! Thank you for taking the time to post. I used to live in SE Washington and have been to ID many times.

[Mtn. States Resident]

Unfortunately, a few of us in the Idaho Falls area learned late last week that the son of a Bonneville High School teacher was among those still not located or recovered. Students and faculty/ staff of BHS are collecting donations to go directly to Snohomish County families. There has not been a link created for this yet.

The story has been on our local news for many broadcasts but I think no one wants to do the wrong thing. I have no idea if the teacher is in ID or WA currently.

If someone has more recent news, a link etc.please post it. Thanks.

[Mtn. States Resident]

Originally Posted by pw72

A lot of this unstable land in Western Washington is built on glacial deposits. In fact, the entire geography of Puget Sound and the formations of the land are the result of a glacial age not that old. (I think within the past 10,000 years, though somebody could correct me). Idaho's geography, with the possible exception of the panhandle, is not the same. However, there was a major slide that shut down a highway in 2011 in far Western Wyoming not far from Jackson. So the jury is out. I would invite experts to weigh in here.

PW-

You called it!

Jackson issues evacuation advisory | Latest News - Home

[Mtn. States Resident]

No longer an Advisory. As of 07:30 p.m. tonight, part of Jackson under Mandatory Evacuation.
Jackson issues evacuation order | Latest News - Home

MSR

[banjomike]

There are lots of moraine rock piles in and around Jackson Hole with very little holding them together.
There are some hillside in Ketchum that could slide if they became wet enough.

[Mtn. States Resident]

Originally Posted by Mtn. States Resident

Unfortunately, a few of us in the Idaho Falls area learned late last week that the son of a Bonneville High School teacher was among those still not located or recovered. Students and faculty/ staff of BHS are collecting donations to go directly to Snohomish County families. There has not been a link created for this yet.

The story has been on our local news for many broadcasts but I think no one wants to do the wrong thing. I have no idea if the teacher is in ID or WA currently.

If someone has more recent news, a link etc.please post it. Thanks.

I'm very proud of the Studentbody, teachers and others who have responded to a teacher's loss in Oso.

While all types of donations are being accepted, Bonneville High School students and teachers have been in direct contact several times with the high school in Oso. What I keep hearing is there is a tremendous need for any type of athletic equipment.

I posted this here, along with a link of Sandhill Media's five minute interview the Studentbody Pres. If those living in other areas of ID aren't aware both of an Idaho teacher losing family and what Oso needs, they may not know how to help, despite their desire to do so.

Here's the interview link:

If all teens and even the elementary schools who helped are training our future leaders, I'm more optimistic about the future!

Thanks

MSR

[chevpu1967]

Unfortunately, we can also ask what can be learned from the Colorado mudslide. *sigh*