Wednesday, April 26, 2017

Orcas, Seals, Dabob Bay and Broad Spit

I was attempting to track down a reference that included the term Broad Spit and got sidetracked by this article from 2012: seattletimes.com/on-dabob-bay-man-and-nature-nurture-preservation.

The article describes an Orca entering Dabob Bay and swimming along the east side of the bay to the head of the bay and then turning back south and swimming down the west side of the bay to Broad Spit. Just south of Broad Spit her/his mates were gathered to prey of the seals that the lone Orca had frightened.

Broad Spit is a cuspate shoreform that protrudes out from the steep shoreline on the east side of the Bolton Peninsula into Dabob Bay.

Upper Dabob Bay with the Bolton Peninsula on the left and Toandos (or Coyle) Peninsula on the right.
Quilcene Bay is to the west of the Bolton and Hood Canal is east of the Toandos
Broad Spit protrudes from the east side of the Bolton

Closer view of the spit

Broad Spit has been located along the shore of the bay for a long time.

1860 survey of the coast



Friday, April 21, 2017

My Lahar/Policy Talk to the Whatcom County Council

A couple of weeks ago I gave a short talk on lahar hazard issues to the Whatcom County Council. The talk was a bit of a follow up on a presentation that had been made to the County Council in February by geologists from the USGS Cascade Volcano Observatory and geologists who work for Whactom County.  The USGS gave a presentation on Mount Baker Hazards and answered questions from the council. 

Council Member Barbara Brenner had asked Don Easterbrook to speak at the Council meeting. Dr. Easterbrook had written to the council (whatcom.wa.us/DocumentCenter/View/27435) that had some contrary opinions to lahar hazard mapping that has been done by the USGS. I was asked by Council if I would be willing to speak on the issue as well. This is in part because of information that I had forwarded to the Council that was contrary to Dr. Easterbrook's views as well as my technical review of the County geology hazardous areas regulations. 

What follows are the slides I used in my presentation which was primarily on process and how public policy regarding geologic hazard and risk can be approached. Some elaboration as fitting is provided below each slide.
  
This slide was simply to go over the recommended geology hazard regulation changes. First I was a volunteer on Critical Areas Ordinance Technical Advisory Committee. (CAO TAC). I noted that most of the changes to geology hazard regulations were pretty minor and indeed none of the changes to the geology hazard code caused any consternation in later public reviews. I did suggest that the tsunami regulations be separated from seiche hazards as the two pose different levels of hazard. Whatcom County has no known seiche hazards but it can not be ruled out. The tsunami hazard is better understood and keeping the two separate made better sense to me. One area of erosion hazard was removed as it is my view that surface water run off erosion is better handled and is handled with other regulations. Lastly I noted that I did nothing with the code in regards to lahars and big landslide hazards due to the lack of policy guidance - it was and is my view that policy should come before code changes.

Just an image of what a lahar deposit looks like with a note that getting hit by this would be pretty destructive and rather difficult to mitigate.

 Front bit for getting to policy guidance.

Language in the Whatcom County plan about Mount Baker. I underlined unpredictable as this was an aspect that I would discuss later.

Goal 10 E lays out the overall goal of the county geohazards approach. Underlined loss of life and expenditure of public funds because both individuals and society should be considered. Volcanic impact areas was underlined because that is why we were having this little talk. The last underlined part is also the area associated with regulations, but I did note that other means can be used to achieve the goal besides regulations alone.

This policy has been in the regulations and is a fairly common approach for infrequent but large geology hazards such as tsunamis and lahars fit in this as well. Generally you want hospitals or emergency response facilities located out of hazard areas.

This policy repeats an aspect of the goal can be achieved using multiple approaches, but again we are here to talk about the regulatory side, but in that regard other approaches that may be used should be considered.

This policy gets into why no action was taken regarding changing lahar hazard at the technical committee review point. Without public process and input making substantive changes would not be appropriate. If the process leads to a level of public risk that is acceptable, then the regulations can be written to meet that acceptable risk level.

This is really the same thing, but perhaps emphasizes approaching each hazard a bit differently.

Suggested approach in a very abbreviated manner. I noted that a new paper which will provide a very good overiew of Mount Baker geology and hazards is in review and will greatly aid in understanding the science.

This is a blank chart that has been used for laying out acceptable risk levels for frequency and fatalities associated with geology hazards. It has been used in Hong Kong and in British Columbia.

The approach has some appeal in that it splits the tasks of plotting the risk between two groups. The geologists figure out what the annual frequency of an event taking place and then planners and policy makers assess the fatalities of the event. More on this chart later.

I lifted the sentence from an article on a completely different science subject, but feel it is applicable. Alas, I lost the reference so apologies to whoever really deserves it. The picture was lifted as well from a volcano hazard presentation from an Oregon County.

The emphasis was to link it to the fact that determining the potential for a hazard event taking place means that there will be scientific uncertainty, and scientists should be comfortable explaining the uncertainty to policy makers. I felt the the USGS folks had done a reasonable job at this during their presentation, but there things are worth repeating.

There is going to be uncertainty and pubic officials have to know that.


For Mount Baker, the history of lahars is a bit short due to the ice age. With one exception all the large lahars that may have come off the mountain have been erased due to the ice age glaciers covering the entire region. The USGS folks did a pretty job of covering this and I was repeating their points.


I put this map up to note that there had been lava flows including the youngest on the mountain that headed north (thanks David Tucker for the help with this). I felt putting this map up was important to counter a map that Don Easterbrook presented that had the exact same reference but left off the youngest lava flows on the north side of the mountain.

 Just repeating myself.

People are not going to be banned from volcanic hazard areas. But it is useful to think about the types of populations and visitors that could be at risk depending on the policy approach and regulations.

With all the words and technical talk that can consume geology hazards, the point can get lost that geology hazards kill people. I will say that I got some push back post the talk about this slide. that push back came from people that are opposed to lahar hazard regulations and they were upset that the slide was playing on emotions. They are right, but I also think that it is too easy when trying to figure out potential hazards and run out distances from lahars or debris avalanches and getting excited about the science and policy impacts to property owners it is worth being starkly reminded about why we are even considering the regulations. The picture is from the Armero tragedy of 1985 when over 23,000 people were killed by a lahar associated with a small volcanic eruption.
 
I got this idea of risk principles and have modified it a bit or a lot.




I noted that existing development was identified at risk elsewhere in Whatcom County and the risk was viewed as high enough that additional actions to protect people was taken. Purchases of very high risk sites and other actions.


 Back to the blank graph.

I do not think the council nor was I ready to plot out any specific scenarios on the chart. But discussed some extreme end points. A 1:100 year event that could kill 10,000 people is not likely a very acceptable outcome.

 What a distal muddy lahar looks like for people escaping.

Besides lahars, large mountainside landslides are a similar problem in the mountain valleys. The LiDAR image above is the town of Glacier. Glacier would be impacted with very little warning time if a lahar or debris avalanche descended down Glacier Creek from Mount Baker. But another hazard is evident at Glacier - the valley floor is covered by a large landslide deposit - the lumpy ground evident in the LiDAR imagery.

Just up the North Fork Nooksack River from Mapple Falls is another area of lumpy ground from a large landslide that covered the valley floor.

This large landslide is east of Kendall. The scarps at the top of the slide appear recent in the LiDAR and I observed fairly fresh fractures on the headwall area of this slide when I last visited the slide.

This slide has been called Devil's Slide and covers the north end of the South Fork Nooksack valley near the confluence with the main stem of the Nooksack River.

Geologists like this, but I also think it is the geologist's job to give notice to civilization and thus change the phrase. To some extent Durant may have been inspired by the destruction of historic sites such as what took place at Vesuvius.

Some credit where it is due. The Scott and others paper is most helpful on the lahar hazard issue. And David Tucker provided some good guidance as well. 

Monday, April 17, 2017

Green Eastern Washington and Palouse Falls Lineup

There is a short window of time every Spring when eastern Washington turns brilliant green. With deep snows and plenty of rain, this year the scrub steppe lands are particularly green as new grass growth covers over the brown grasses of the year before.

Horse Heaven Hills with green and more rain showers in the distance



Devil's Canyon was brilliant green
and in sharp contrast to the last time I visited

Devil's Canyon late January 2017

With the heavy snow and cool Spring, word was out that Palouse Falls was putting on a show. Since I was passing by on a Saturday, the crowds were lined up. The State Park employee at the entrance said folks were having to wait close to 2 hours as the park was full.

Lineup to see the falls



  

Wednesday, April 12, 2017

Slide Causing Highway 530 Closure

The landslide that caused the closure of the State Highway as well as evacuations of a few homes is labeled in the LiDAR imagery below at the Montague Slide (my name as it is located just west of a creek by that same name).


I had initially presumed that the Skaglund Hill slide had moved as it has caused road problems in the past. The Montague slide is not a new slide. LaHusen and others (2015) estimated that the Montague slide was less than 500 years old based on surface roughness from LiDAR combined with carbon dates from several locations on nearby slides. The recent sliding on part of the Montague slide area will add some new roughness.

The slide itself has not impacted the highway; the highway is below the slide area. The concern is that the slide may become very active and slide down onto the valley floor and the highway. Hence, some monitoring of slide movement before any further decisions regarding the highway. 

Saturday, April 8, 2017

Swift Creek Landslide and Creek Update

The Swift Creek landslide  continues to present challenges to Whatcom County Public Works (Click on the tag at the bottom of this post to get all the previous posts). The bridge at Oat Coles Road has been removed. The bridge was removed to prevent it from being damaged and to minimize the flooding that would be caused by the bridge causing a blockage of the sediment filled creek. The County is planning to put a one lane bridge with a control light to allow access for local traffic.



Flood waters can cause problems, but at Swift Creek the problem is even worse because the sediment carried by the creek contains asbestos form minerals. Hence, the effort to minimize the flood potential. The bridge is located nearly 2 miles from the landslide.

Swift Creek with landslide area outlined in red

Dredge spoils on both sides of the creek viewed from the north

It is hard to capture the scale of this problem. And it is a problem that will not be going away. The slide shows little sign of stopping. Linneman (2016) estimates that the main body of the slide is moving at 2 to 4 meters/year.

The Washington State Senate has included $5.5 in its current budget for Swift Creek. Two years ago the money was in that State Budget proposal but got pulled at the last minute by the local State Senator Doug Ericksen in favor of directing money elsewhere. The budget process is not over for the state, but for Whatcom County the news is so far good.   

Friday, April 7, 2017

The English Channel and Eastern Washington

A few news outlets have had fun with a new geology paper and Brexit. Gupta and others (2017) used high resolution sonar imagery as well as seismic line investigations to support a theory about the formation of the Dover Strait and the formation of Great Britain as an island. Hence, the term Brexit being applied by news stories about the paper. The resemblance to eastern Washington landscapes of the sonar imagery is striking.

From Gupta and others (2017)

Smith (1985) proposed that the Strait of Dover was carved by a large glacial age flood event. That idea has gained strong support (see for example Gibbard (2007) and Gupta and others (2007)).

Gupta and others (2017) further support the idea of a huge ice-age flood using far higher resolution data than what was available to Smith (1985), and their recent work helps refine the idea. They noted similarities between the topography in the Dover Strait and the landscape of eastern Washington's Channeled Scabland, "We interpret the amphitheater-shaped channel heads as abandoned cataracts formed by focussed knickpoint popagation similar to those formed by high-magnitude floods in the Channeled Scabland, Snake River Plains and Iceland".

Wednesday, April 5, 2017

Channel Shifting on an Alluvial Fan

Four hazards are typically present on alluvial fans: 1) debris flows, 2) debris floods, 3) flooding, and 4) erosion. The debris flows and floods are the most worrisome because of their suddenness and violence. In many cases they are rare events which makes them more dangerous particularly in areas that have no previous recorded history of debris flow or debris flood events.

Another hazard on alluvial fans is the tendency for the stream channel to become filled with sediment and the stream then moving to another location on the fan. The new flow path causes flooding but also can cause significant erosion as the stream erodes into its new channel. This hazard can be mitigated, but in some cases it is a too costly a fight. 

Last week I got some experience on an alluvial fan stream that has left its old channel of many decades and has begun the process of establishing a new channel on the fan surface.