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"And the Landslide Brought Me Down: A glimpse into the hazards and joys of living in Tacoma's Salmon Beach Community." by Kyle Sleeper  This wikispace is a collection of pictures and research I've done for a summer course focusing on various environmental catastrophes. My area of study is the residential community known as Salmon Beach located on Puget Sound in Tacoma, Washington. Quite literally. Its proximity to the ocean exposes the community to both land and sea hazards. On land it is prone to landslides, and has had multiple large-scale slides causing damage and even death. In the event of a large magnitude earthquake, the saturated ground which Salmon Beach rests upon is prone to liquefaction. From the ocean residents can also expect both tsunamis and seiches.

 A __feeder bluff__ is an eroding landmass that provides fresh sediment to replenish beaches and provide nourishment for water based ecosystems. An __earthquake__ is the rapid release of stored energy from motion along a fault. A __landslide__ is the gravity-driven down-slope movement of a slide mass composed of rock, soil, and vegetation. __Liquefaction__ is the process of loosely packed, water-logged sediment, coming loose from intense vibrations, like the shaking of an earthquake. __Seiches__ are water waves generated in enclosed or partly enclosed bodies of water such as reservoirs, lakes, bays and rivers by the passage of seismic waves caused by earthquakes. A __tsunami__ is a large and fast wave generated from the displacement of a large volume of water beneath the surface.
 * Some important terms to know: **

- There are many factors which influence a landslide including groundwater conditions, steepness of slope, soil composition, and human related activities. Salmon Beach has experienced landslides and other environmental damages which have caused nearly $2 million in damages. - The cliff above Salmon Beach is made up of layers meant to move: silt and clay at its base, followed by a layer of sand and gravel, followed by more silt, sand and glacial till. Interwoven through it all is a series of springs, some of which gush into small waterfalls at the base of the bluff.
 * Facts worth noting:**

- A landslide at Salmon Beach occurred in 1949 three days after a surface-wave magnitude 7.1 Olympia earthquake. - In 1996 heavy rains caused a landslide destroying 3 homes. - In February 2001 the Nisqually Earthquake caused a slide the resulted in severing municipal services and damaging 8 houses.





Some city engineers don’t believe in issuing permits for building in Salmon Beach because it’s not natural to put houses beneath eroding bluffs, which are important aspects of the Puget Sound environment. Called “feeder bluffs,” the sand and gravel constantly wash down into the beach and is picked up by the water to be deposited onto other beaches, replenishing their sediment levels. It would take a multimillion-dollar project to shore up the bluff enough to prevent major slides. And because that's a cost that would have to be borne by the residents of Salmon Beach, it probably will never happen.

Located directly on the sound, one must constantly be aware of tidal changes and seismic events causing tsunamis and seiches. A project is underway to assess the tsunami hazards within Puget Sound communities and to provide information for tsunami planning and mitigation “using a finite difference model based on nonlinear shallow water wave theory and high-resolution digital elevation model, we simulate the generation, propagation, and inundation of tsunamis in Puget Sound. The tsunamis are generated as a result of possible earthquake scenarios for the Seattle Fault.” According to a study done by Atwater and Moore evidence for major tsunamis have been found in the geologic record: “Water surged from Puget Sound sometime between 1000 and 1100 years ago, overrunning tidal marshes and mantling them with centimeters of sand. One overrun site is 10 kilometers northwest of downtown Seattle; another is on Whidbey Island, some 30 kilometers farther north. Neither site has been widely mantled with sand at any other time in the past 2000 years. Deposition of the sand coincided—to the year or less—with abrupt, probably tectonic subsidence at the Seattle site and with landsliding into nearby Lake Washington. These findings show that a tsunami was generated in Puget Sound, and they tend to confirm that a large shallow earthquake occurred in the Seattle area about 1000 years ago.”

Here is a YouTube video I made describing some of the hazards associated with Salmon Beach:

media type="youtube" key="lbgy1cmCAw4" height="385" width="640" align="center"

If you want to access the paper I wrote on Salmon Beach, or a powerpoint presentation, you can find them here:





REFERENCES:

http://landslides.usgs.gov/recent/archives/nisqually/

http://wcatwc.arh.noaa.gov/web_tsus/19490413/narrative1.htm

http://www.tacomaculture.org/historic/districts_salmonbeach.asp

http://www.fema.gov/news/dfrn.fema?id=946

http://www.seattlepi.com/local/21169_salm02.shtml

http://www.ecy.wa.gov/pubs/81e13.pdf

http://www.arcadiapublishing.com/mm5/merchant.mvc?Screen=PROD&Product_Code=9780738531083

http://www.co.pierce.wa.us/xml/abtus/ourorg/dem/EMDiv/R5MP/Landslide.pdf

http://nctr.pmel.noaa.gov/pugetsound/pre2/

http://www.pmel.noaa.gov/pubs/PDF/vent2981/vent2981.pdf

http://www.co.pierce.wa.us/xml/abtus/ourorg/dem/HIVAWEB.pdf

http://www.sciencemag.org/cgi/content/abstract/258/5088/1614

http://www.seattlepi.com/local/quak22.shtml

An Account of Preliminary Landslide Damage and Losses Resulting from the February 28, 2001,Nisqually, Washington, EarthquakeBy Lynn M. Highland USGS

Lander, J.F., P.A. Lockridge, and M.J. Kozuch (1993). //Tsunamis Affecting the West Coast of the United States 1806-1992, NGDC Key to Geophysical Record Documentation No. 29, NOAA, NESDIS, NGDC, 242 pp.//

Pierce County Landslide Hazard PDF: http://www.co.pierce.wa.us/xml/abtus/ourorg/dem/EMDiv/MP/PC%20Landslide.pdf

NOAA Technical Memorandum OAR PMEL-132: TACOMA, WASHINGTON, TSUNAMI HAZARD MAPPING PROJECT:MODELING TSUNAMI INUNDATION FROM TACOMA, Arcas, Mofjeld, Titov, Chamberlin, Gonzalez, Venturato

B Atwater and A Moore, “A Tsunami About 1000 Years Ago in Puget Sound, Washington,” Science. December 4th, 1992. 1614-1617

If you have knowledge you wish to contribute to my project, or if you are a Salmon Beach resident willing to be interviewed, please contact myself at ksleeper@pugetsound.edu, or my professor Mike Valentine at mvalentine@pugetsound.edu.