Stillaguamish

Deadly mudslide in Washington

This image, taken from an airplane, shows the best view I’ve seen of a mudslide just east of the town of Oso in rural, northwestern Washington State.

The mudslide occurred at about 10:45 a.m. on the morning of Saturday, March 22nd along the Stillaguamish River. As of the time of this writing, there have been 8 people confirmed dead but today searchers stunned the press by reporting that the list of potential missing includes up to 108 names.

The searchers stress that the list includes vague descriptions like “John who once lived in this neighborhood”, so the total of missing should not be immediately interpreted as a possible death toll. The mudslide hit 49 different lots containing property, at least ½ of which were believed to be occupied full time, and buried Highway 530 – the only route to a nearby town of 1,359 called Darrington.

The slide also completely blocked the Stillaguamish River, reducing its output to a trickle. When landslides occur, they can completely block rivers, creating lakes behind them that eventually overtop the dam leading to a major flood. Flood warnings have been issued on the river, but most likely some degree of digging/dredging will open up a flow path to let the water slowly pass through.

The rocks that collapsed appear to be loosely-consolidated, possibly-glacial sediments. Similar events are common in this area; the state of Washington recently completed a $13 million project to stabilize a portion of hillslope on the opposite side of the river from this slide. Additionally, this area has endured significant rainfalls over the past several weeks, although there was no specific storm right before this slide. Instead, the amount of rain caused buildup of groundwater pressures in the area, and eventually this groundwater pressure allowed the hillslope to give way. Rainfall totals during the month of March in this area are about 300% above the average totals for the month.

Layering in the disrupted central block appears somewhat intact and can be seen in this photo; the slide broke away along an arcuate scarp and left debris piles that are reportedly up to 4.5 meters (15 feet) thick.

From here, search teams will have to simply dig through significant portions of that sediment to try to locate and identify those missing, in addition to digging through that big pile of dirt to prevent flooding on the river.

-JBB

Image credit: Washington State DOT via Reuters/NBC
http://www.nbcnews.com/storyline/deadly-mudslide/washington-mudslide-toll-rises-eight-least-18-missing-n59981

Read more:
http://blogs.agu.org/landslideblog/2014/03/23/oso-landslide-1/
http://news.nationalgeographic.com/news/2014/03/140324-mudslides-natural-disasters-geology-science/
http://www.slate.com/blogs/future_tense/2014/03/24/oso_wash_mudslide_climate_change_may_bring_more_such_disasters.html
http://www.cnn.com/2014/03/23/us/washington-landslide/
http://www.latimes.com/nation/nationnow/la-na-washington-mudslide-108-missing-search-20140324,0,7984706.story#axzz2wu5DV3ch
http://www.stltoday.com/news/national/voices-crying-for-help-stop-in-washington-mudslide/article_7802d13b-177e-5bff-9ec3-117f9dd494e5.html

2015/2/21 - Morning Star Peak

This is a concise, high-level trip report. For detailed scramble route descriptions see nwhikers.net or summitpost.org.

My second time setting foot in the South Fork Stillaguamish River basin in a little over three years, and not much has changed, Other than peakbaggers and scramblers, the basin doesn’t get too many visitors due to brush and rock debris.

Located the faint climbers path turnoff immediately before Stillaguamish River crossing and started traversing southerly. Two hundred feet into the path the tall alder began to appear. The alder had completely taken head of the basin so the path was nearly unrecognizable. The fight with the alder continued for about 300 feet, then followed by another 300 feet of brush. By now, the hikers path had completely disappeared but we now had an open view of the basin. Sitting at the head of the basin is the imposing Del Campo Peak’s north face. (pictured)

After identifying the house-sized boulder, we the made our way over to the ramp along side the long, continuous slab wall. The ramp was fully of nothing but brush and alder, and it took some time to route find and slowly made our way up to the knob, which marked end of the ramp. Snow appeared around 4000’ and we saw some old boot tracks heading in the same direction.

There were about six inches of recent snow, presumably from the previous one night or two. The closer we got to the notch the more ice we felt underneath the new snow, and this would have been a good place to put on crampons to avoid sliding. Snow condition on the west side of the notch was much better as it had been in the sun for a couple of hours and wasn’t as icy. The gully on the other side of the notch was just as steep and icy as it had been described in other trip reports. The rocks to the right of the steep gully were exposed so I climbed on rocks instead and met up with my climbing partner stayed at the base of the summit block.

The west slope leading to the summit had just seen the sun when we arrived so it was still icy. With my spikes on and lots of veggie belay, I continued to mix climb when I could to avoid the icy areas. Climbing partner couldn’t get good foot holds so he decided to put on crampons. The snow condition got better as we got closer to the summit.

We spent quite some time on the summit because the weather was just too good for us to leave. The closeup view of Del Campo and Gothic Peaks was just breathtaking, and to the north Mount Baker was completely out of the clouds. Although the nearby eastern peaks were covered in clouds so we couldn’t get a good look at the Monte Cristo group, Sloan Peak, or Glacier Peak. We waited a while but the clouds were just too stubborn to move out of the way. Other than that, we were able to see peaks in all other directions.

On the way down, I put on crampons to better grip onto the icy slopes and it made the traverse back so much more enjoyable. Another beautiful day out on Mountain Loop Highway!