Could a Pakistan-like event happen in Washington State?

As posted on my previous post, a large landslide has blocked a river in northern Pakistan. The slide blocked a critical road that is the only access through this portion of the mountains. The dammed up river is now flooding villages upstream and the risk downstream is substantial as the river rises with the risk of a sudden failure of the landslide dam and subsequent floods.

Washington State has steep mountains that have very steep valleys. Could large mountain landslides happen here? That answer is easy. We have had several of various scales. The most recent was the Naches/Nile River slide in 2009. This slide destroyed several homes, buried a state highway and dammed a river.

In 1964 the Hope Slide blocked Highway 3 in southern British Columbia. Somewhere under the piles of rocks are buried cars where people who were at the wrong place at the wrong time were driving.

The Frank Slide in southwest Alberta killed 70 people, blocked a railroad and buried the entrance of a coal mine with people inside. The miners were able to dig their way out.

Several large landslides have been identified in the steep valleys of northwest Washington. The Church Mountain landslide buried the North Fork of the Nooksack River. The town of Glacier and other home subdivisions are built on top of the landslide debris form that slide. David Tucker provides a field trip guide to the Church Mountain slide at Here as well as a trip to a lake deposit up the Skagit Valley from a slide that dammed the Skagit River Here.

LIDAR images of the mountains in Whatcom County identify numerous mountain size failures. As I posted before Here numerous slides are located on the slope of Sumas Mountain including the active Swift Creek slide on the west side of the mountain described in part in this post Here.

Perhaps the most impressive and most dangerous is the Bonneville slide complex on the Columbia River. The Bridge of the Gods slide that dammed the Columbia River in the Columbia River gorge. This slide was described by native people living in the gorge and it was obvious to Lewis and Clarke that the slide was a recent feature. This slide altered politics on the Columbia River as it blocked passage on the river first as a dam and then as a steep rapids. There is evidence that a massive flood 80 feet above current flood levels took place downstream of the dam when the landslide blockage was breached.

Lewis' map of the slide area.

As can be seen in this Washington State Department of Natural Resources map multiple slides have taken place at the Bonneville site. The current lake is the result of Bonneville Dam, built on the slide deposits. Major power lines, pipelines and highways use this natural corridor. Another slide at this site will have profound impacts on Washington State and Oregon. The fact that the slide is not ancient history causes one pause to think how it impacted people living in the area a few hundred years ago. It had a profound impact then and it will when the slope fails next time.

More Trouble in Pakistan

I do a fair bit of landslide work and so try to stay up with the science. I have been following the developments associated with a very large landslide in northern Pakistan. This slide took place in one of the most rugged landscapes inhabited by humans on the planet. It completely blocked the road between Pakistan and China. Its must be an amazing road to travel as it crosses just in front of huge valley glaciers, crosses very active alluvial fans and the entire valley is hemmed in by huge mountains.

I recently took a look at the satellite imagery accessed via Google and found that a newer high resolution view of the area shows the slide and the lake forming behind the slide. An older view of the river prior to being backed up can be seen on the right of the image. The yellow line is a rough approximation of the road route. The lake has inundated the bridge that formerly crossed the river to the northeast in the image.

The risk now is that the landslide dam will fail suddenly as the water levels behind the dam rise. Geologic evidence downstream indicates this sort of event has happened in the past and there are what appears to be lake terraces up stream from past landslide dammed lakes. Pakistan government has been excavating an emergency spillway to reduce the final height of the lake and reduce the risk of a catastrophic breach of the landslide dam. But this is an emergency effort with very limited time. It has been a heroic effort given the conditions and location. One worker was killed from further rockfalls on the slide. He was not able to hear the crashing boulders that were approaching as he was operating an excavator.

As the spring snow melt begins the lake will fill rapidly. The anticipated date of the dam being over topped is in about two weeks. 

Ophiolites and being a Grunt Geologist

I sometimes refer to myself as a grunt geologist. Grunt geologist do not have as much time to pursue geologic observations as much as they would sometimes like. Lately I have been doing a fair bit of small field site visits and I just completed a report that I would once describe as a thesis. I now can describe in detail the aggregate resources in Clallam and Jefferson County. But outside of a narrow self interested group, I would likely put anyone asleep with stories about sand and gravel deposits.

Field work the past two weeks has been damp and chilly. The field work has been followed up with lots of writing including the aggregate study. Below is a view looking north from Fidlago Island to Cypress Island, one of the Jan Juan Islands. I took the picture during a small project assessing a slope on a chilly wet late April afternoon. Cypress is one of the San Juan Islands that is actually not in San Juan County. It is in Skagit County. Most of Cypress is protected as a Natural Resources Conservation Area and as a Natural Area Preserve.  

The shoreline along Fidalgo Island I was traversing involved technical crawling. Lots of sharp boulders covered with very slippery oak leaf seaweed.

The boulders consist of ultamafic rocks of the Fidalgo ophiolite. Ultramafic refers to the fact that these rocks are very high in iron and magnesium content relative to most rocks. An ophiolite is a section ocean crust. These rocks are part of an ocean basement that somehow got thrust up and accreted to the edge of North America. The Fidalgo ophiolite is part of a complex assemblage of rocks making up parts of the San Juan Islands and the Northwest Cascades that is referred to as the San Juan - North Cascades Complex. The complex is well very complicated and not necessarily for the understanding of a grunt geologist like me just trying to figure out if a slope is stable. But it was fun to use the term ophiolite in a report. And I enjoyed observing the mineralogy and layering that only a metamorphic petrologist or a student of deep ocean crust can fully appreciate. And besides I once spent a fair bit of time helping try to sort out some the pieces of the puzzle explaining how these rocks ended up here as a graduate student.

Badger Mountain versus Skagit Valley Tulips

                                

Long leaf phlox

I took a hike up Badger Mountain south of Richland, Washington late last week. I did the same hike last November. This time of year is a great time for flowers and the hike did not disappoint. My ability to identify very many plants and flowers is severely limited, but regardless I can still appreciate the flower display. It’s a great hike with sweeping views covering hundreds of miles and lots small scale things to observe as well. This time of year provides the best flora displays, but there are lots of other plants that will bloom later and some that have barely begun to grow.

Carey's balsamroot

Cushion fleabane

Rosey balsamroot

Upland larkspur

Bingen lupines

This is the first of a series posts I am planning on Badger Mountain and the broader landscape that includes Badger Mountain. Part of what I want to do with Reading the Washington Landscape is to better understand the landscapes we see in Washington. Badger Mountain looks the way it does because of its geology, climate, ecosystem, history and land use policies. More posts on those subjects will follow. And I will add future land use policies will define greatly how Badger Mountain will look in the future.

Thanks to all the hard work from Friends of Badger Mountain  http://www.friendsofbadger.org/ . They have worked to make a great landscape even better.

Waiting for Summer

"And keep in mind that summer generally start around here a week or two after the July 4th weekend."

I have been distracted by other activities so have not  put up anything I think might be of interest. Work, some local growth planning, taxes have all kept me distracted. But the above line from Cliff Mass’ Weather Blog tells us a lot about western Washington. I do sometimes wish it did not have the ring of truth it does. Mr. Mass’ blog link is on the side bar and I check it frequently. It is mostly weather related but he does talk about other things close to my heart like math in schools – I taught math for several years including teaching algebra in the school auto shop.

Toandos Bear to Crescent Formation Pillows to Crazy Roots

Yesterday was my first bear encounter of the year. I have no expertise estimating bear size as I have never attempted weighing a bear, but I’d estimate it was a 250 pound bear as the bear appeared bigger than me by a fair bit. But then bears within 50 feet always loom a bit large. The encounter was short as the bear had no interest in interacting. It was the first bear I have ever seen on the Toandos Peninsula despite many trips there and having seen plenty of bear evidence. The Toandos is a long peninsula with Hood Canal as its east shore and Dabob Bay as its west shore.


The other highlights of the day were “discovering” a new large landslide on the Toandos, observing the basal till contact on pillow basalts of the Crescent Formation along Hood Canal, seeing an impressive root structure of a red alder clinging to a steep slope, and avoiding sinking up to my knees while traversing a tide flat on the Duckabush River.

Headwall scarp of large landslide. The slide involves approximately 50 acres of land.

Pillow basalts of the Crescent Formation. The basalt erupted on the ocean floor approximately 55 to 55 million years ago.

Red alder roots can't penetrate the basal till. The till was depsoited directly by glacial ice. Clasts in till consist primarily of the underlying basalt. 

April Showers and a Hanging Garden

Field work today entailed a trip up the Skagit Valley. The low pressure system off the coast was causing a strong east wind out of the valley this morning. Not an uncommon phenomenon.
Up the valley it was wet and cold and with ice in the rain drops. One reason western Washington has such thick vegetation like that described in yesterday’s post is the rain. I have little to complain about though as this winter was very mild. The weather today may have been the worst I have been in since - well last April.

This big leaf maple growing along the flood plain of the Skagit River had created an impressive hanging garden, a common characteristic of big leaf maples.