Trying to keep track of all of the landslides occurring in Washington State is a difficult task. Normally, I hear about most of the important ones via media reports, but this one escaped me, probably because of all of the activities following the January 7-8th storm.

National Park Service Morning Report

“On Friday, January 16th, a large landslide occurred adjacent to the Spokane River near Mill Canyon. Homeowners in the Mill Canyon area contacted the park and reported that their docks had been destroyed by a large wave. Responding rangers found that a section of hillside measuring approximately 17 acres in size had broken free across from Breezy Bay and that the subsequent landslide had fallen into the water, creating a wave that was about 30 feet high when it hit the southern shore about a thousand yards across the lake. The wave damaged or destroyed several private docks located at Breezy Bay, Moccasin Bay, Sunset Point and Arrowhead Point. Several vessels moored in the area were also swamped and left beached on land. The water reached one residence before receding and came just to the foundations of several others. The full extent of the damage caused by the landslide is not yet known. Damage to property was documented as far as a mile and a half downstream, and significant resource damage and erosion to the shoreline occurred as far as three miles downstream. The park has issued a general safety warning due to the debris in the water, which is making navigation difficult. Boaters in the area have been advised to use extreme caution when boating from Cayuse Cove to Breezy Bay on the Spokane River. Along with ice deposits in the lake, there are now large trees, dead heads, dock parts, and unknown sediment deposits that have made safe navigation difficult. Due to unknown conditions near the slide, visitors are also being advised to avoid going on land at the site, as the ground will be quite unstable for some time and sinkholes and falling debris may occur. [Submitted by Adam Kelsey, Acting Chief Ranger]”

Lake Roosevelt Landslide?

Lake Roosevelt Landslide?

I am attempting to contact Ranger Adam Kelsey in regards to the exact location and any additional information on the landslide.

A good friend of mine and coworker, Trevor Contreras, ran across this photo of the suspected bluff in Cruden and Varnes (1996) landslide processes paper:

Lake Roosevelt Landslide - Cruden and Varnes

Lake Roosevelt Landslide - Cruden and Varnes

This before photo clearly shows little debris at the base of the bluff. and gives an approximate idea of how large the landslide is in size.

Past History
Lake Roosevelt National Park has a long history of landslides. I recall a document by the Emergency Management Division of Washington Military Department regarding landslide histories in this document
“• 1944 to 1953 – Massive landslides generated a number of inland tsunamis in Lake Roosevelt in Eastern Washington:
• April 8, 1944 – A four to five million cubic yard landslide from Reed Terrace generated a 30-foot wave, 5,000 feet away on the opposite shore of the lake about 98 miles above Grand Coulee Dam.
• July 27, 1949 – A two to three million cubic yard landslide near the mouth of Hawk Creek created a 65-foot wave that crossed the lake about 35 miles above Grand Coulee Dam; people 20 miles away observed the wave.
• February 23, 1951 – A 100,000 to 200,000 cubic yard landslide just north of Kettle Falls created a wave that picked up logs at the Harter Lumber Company Mill and flung them through the mill 10 feet above lake level.
• April 10 – 13, 1952 – A 15 million cubic yard landslide three miles below the Kettle Falls Bridge created a 65-foot wave that struck the opposite shore of the lake. People observed some waves six miles up the lake.
• October 13, 1952 – A landslide 98 miles upstream of Grand Coulee Dam created a wave that broke tugboats and barges loose from their moorings at the Lafferty Transportation Company six miles away. It also swept logs and other debris over a large area above lake level.
• February 1953 – A series of landslides about 100 miles upstream from Grand Coulee Dam generated a number of waves that crossed the lake and hit the opposite shore 16 feet above lake level. On average, observed waves crossed the 5,000-foot wide lake in about 90 seconds.
• April – August 1953 – Landslides originating in Reed Terrace caused waves in the lake at least 11 different times. The largest wave to hit the opposite shore was 65 feet high and observed six miles away. Velocity of one of the series of waves was about 45 miles per hour.”

Some more history from Stevens County in chapter 5 of their Multi-Hazard Mitigation Plan

“• April 8, 1944 – A four to five million cubic yard landslide from Reed Terrace generated wave, 5,000 feet away on the opposite shore of the lake about 98 miles above Dam.
• April 10 – 13, 1952 – A 15 million cubic yard landslide three miles below the Kettle created a 65-foot wave that struck the opposite shore of the lake. People observed six miles up the lake.
• February 1953 – A series of landslides about 100 miles upstream from Grand generated a number of waves that crossed the lake and hit the opposite shore lake level. On average, observed waves crossed the 5,000-foot wide lake in about
• April – August 1953 – Landslides originating in Reed Terrace caused waves in the 11 different times. The largest wave to hit the opposite shore was 65 feet high and miles away. Velocity of one of the series of waves was about 45 miles per hour.”

So, what is causing all of these landslides? The USGS in their report on significant landslide events in the United States summarizes:

“In summary the shores of Roosevelt Lake have been subject to several hundred landslides since the reservoir began to be filled during construction of Grand Coulee Dam during the 1930’s and early 1940’s. The greatest percentage of landslide activity occurred during initial filling of the reservoir, but many slope failures also have been caused by intermittent drawdown of the reservoir level. In addition, occasional slope failures have occurred as natural phenomena, related more to wet winters than to fluctuation of the reservoir.”

Static Liquification from water level changes and changes the surrounding hydrology probably does play a big roll in landslides, it is something that you can see in most of our major dammed lakes. There might be other triggers as well.

Lake Roosevelt Landslide

Lake Roosevelt Landslide

In eastern Washington, there are certain triggers when looking at landslides. Potentially, agriculture can play a role in landslides along bluffs and in the long-term, the watering of crops above these bluffs does play a role. Chances are, they weren’t watering in January. The area also had a huge amount of snow this winter and January 16th was in that period where we had a warming trend. So, perhaps snow melt helped to increase the amount of water into the subsurface as well.

One of the things I have grown up with while working at DNR is LiDAR. Actually, it took me awhile to start using LiDAR, my first projects for identifying landslides used aerial photos and 10m DEMs. Not the easiest way to go once you learn to use LiDAR.
Here is an example of some very clear and fascinating landslides in Whatcom County.

Whatcom County Landslides

Whatcom County Landslides

Isn’t that the best thing since sliced bread???

Yesterday, DNR released a report on how public and private lands complied with forest practice rules. The report can be downloaded here.
Compliance was at about 87% for road and road activities and 75% for other forestry related activities (for example, logging), focusing on areas adjacent to streams. When I was in school, 75% was never a good grade. On page 43 of the report, the biggest number of non-compliant Forest Practice Applications (FPA) found were located in Pacific Cascade Region and to a lesser extent, Northeast Region. A closer view of Pacific Cascade Region can be viewed on page 36-37.

So, how does this relate to landslides? SW Washington is probably one of the most unstable areas in Washington State. Continental glaciers buried or carved most of the Puget Sound basin, which in many respects, reset the weathering depth within that area. In the SW, no large continental glaciers have carved and buried the land, resulting deep-weathering and increased instability. Plus, we have had two consecutive years of strong storms impacting western Washington. In both storms, Lewis County and in general, SW Washington, has been devastated by landslides. It would be interesting to see if these non-compliant FPA’s resulted or triggered a landslide.


April 28, 2009

In the world of landslides, there is something like a secret underground of meetings and groups. Technically, I think these groups are open to whomever wants to go. So, here is the tangled web of groups and subgroups. First off, Cooperative Monitoring, Evaluation and Research (CMER), which is hard to explain everything they do, but basically a research and policy type group that uses science to improve the management of Washington State Lands. A subset of that group, which mostly deals with landslides (and policy), is UPSAG (Upland Processes Scientific Advisory Group). It is full of government, environmental, and private (timber companies mostly) people, which makes the conversations entertaining. The part that I like best about the group is most of the people there use science as their talking points on where focus should be steered. Probably some of the most interesting science studies I have seen come out of the meeting is from Weyerhaeuser, which is led by Ted Turner. I wouldn’t say I am a industry supporter, but I am not anti-industry, I try and base my opinions and thoughts on what science points to and look at the risks we take in our management.
Another subgroup, which is part of CMER, is the TAG (Technical Advisory Group), which if I understand it right, is a group that advices projects funded or supported by CMER. Yesterday, I attended a TAG meeting on a project known as the LHZ (Landslide Hazard Zonation) Project. The LHZ project is how I got started at DNR, when I came aboard about November 2004. It was a mixed bag, we were pressed hard to perform and two of us on the group consistently worked 60-80 hour weeks to meet the deadlines. Others who didn’t were pressured even harder to get products out quicker. The good part, I learned more than I ever thought I would about landslides and forestry. It culminated in a talk I gave at a CMER Science Meeting (watch me here). A lot of the talking points at the TAG meeting were the same issues when I was aboard the project, which reminds me of how some things never change. I have a lot of faith in the LHZ project, I think if it was used correctly, it would improve the management of our forests. Unfortunately, talking to some of the foresters out there, sometimes they don’t know the product exists and when they do, they are not aware of how to use it. Sometimes I think managing land should be the same as the Growth Management Act (GMA) or Critical Areas Ordinance (CAO), one must use best available science to help best manage where growth should occur. Luckily, that is what UPSAG strives to do, but I don’t think it is mandatory, yet.

Each week we will feature a new landslide in Washington State. Washington State is covered with dynamic and sometimes quirky landslides.

Alderwood Landslide

As part of a statewide effort to map unstable landforms in forested watersheds, landslides in the Mason Watershed Administrative Unit (WAU) were evaluated using lidar, orthophotographs, aerial photographs dating from the 1960’s to 2000’s and reconnaissance field work. During our landslide study, the Alderwood landslide was identified as a major complex in Hood Canal that may have been triggered by seismic shocks. The Sunset Beach fault runs parallel to the Alderwood landslide and intersects with the headscarp. Trench stratigraphy showed one surface displacement event, which is younger than 1.3 thousand years (personal communication, Alan Nelson, USGS).

Alderwood Landslide in 2002 Mason County LiDAR

Alderwood Landslide in 2002 Mason County LiDAR

A tsunami deposit observed by Jovanelly and Moore, 2005, is located to the northeast of the Alderwood landslide. This study indicates that this deposit was correlated to a seismic event approximately 1,100 years ago (Jovanelly and Moore, 2005; Moore, 1991) . The correlation between the tsunami deposit and activity along the Sunset Beach fault make this landslide complex an ideal origin for the tsunami deposit in Lynch Cove (Bucknam, et al, 1992). Wood samples from a core of the sag pond, to shattered till below, dated at 900AD (limiting age).

Geologic cross section of Alderwood landslide

Geologic cross section of Alderwood landslide

One of the most interesting things about this landslide is its similarity to landslides that moved during the 1964 Good Friday earthquake in Alaska. Looking at cross sections from Turnagain Heights and Government Hill landslides show similar lateral spread and earthflow processes (Barnhardt and Kayen, 2000; Hansen, 1965). This has some interesting implications, are Washington’s Puget Sound shorelines vulnerable to lateral spreads during large Cascadia Earthquakes (like the January 26, 1700 earthquake), or is this a fluke or a confluence of numerous factors, such as a fault along the shoreline?

Turnagain Heights Landslide

Turnagain Heights Landslide


Barnhardt, W.A.; Kayen, R.E., 2000, Radar Structure of Earthquake-Induced Coastal Landslides in Anchorage, Alaska, Environmental Geosciences, Volume 7, Number 1, 2000 38-45.

Bucknam, R.C.; Hemphill-Haley, E.; Leopold, E.B., 1992, Abrupt uplift within the past 1700 years at southern Puget Sound, Washington: Science, v. 257, p.1611-1614.

Hansen, W. R., 1965 Effects of the Earthquake of March 27, 1964, at Anchorage, Alaska, USGS Professional Paper 542-A.

Jovanelly, T.J.; Moore, A.L., 2005, Tsunami origin for an 1,100 year old enigmatic sand sheet in Lynch Cove, Puget Sound, Washington, U.S.A. [abstract]: Geological Society of America Abstracts with Programs, v. 37, no. 7, p. 65.

Moore, A.L., 1991, Evidence for a tsunami in Puget Sound 1,100 years ago [abstract]: Eos (American Geophysical Union Transactions, v. 72, no. 44, Supplement, p. 315.

Slip Sliding Away

April 24, 2009

Today I am still anxiously waiting for the final budget from the legislature to be finalized.  The budget itself, although sounding painful for the general public and poor, doesn’t directly affect my position, although once it passes, the management at DNR will release which people stay and which will be shown the door.  Geologic Hazards has been in the cross hairs for quite awhile, being targeted by the Governor’s budget.  Not only would this mean my position would probably be terminated or I would be shuffled around, but Washington State wouldn’t have anyone to document or respond to future landslide events.

I did a quick calculation as to how much land mass is covered by landslides, mapped within our landslide database.  It is about 1.5-2%, or roughly 1,000-1,400 sq mi (2,800-3,700 sq km), and that is all we know about.  Each year, landslides cause tens to hundreds of millions of dollars in damage.  Washington is covered in landslides, from small itsy bitsy soil sluffs to massive landslides that are some of the largest terrestrial mega landslides in the world (Malaga or Stemilt Landslide).  In the good ol’ USA, we are in the top 10 most unstable states and if records were better kept, I would say top 5.

So, where does that put us?  The DNR and specifically the Washington Geological Survey is one of the only agencies in Washington State studying and recording landslide data.  We have a staff of 6 people in Geologic Hazards, 2 work on landslides full time.  Someday, it would be nice to see landslides taken seriously as a major geologic hazard in Washington State.

So, here is a song to start off this blog:

And you thought it would be Paul Simon…