by ensuring proper resources and planning for emergencies.
Focus: ALL HAZARDS
Sitka’s isolated location creates unique planning requirements. In an emergency, the community will need to rely on local resources and depend on the cooperation of its residents to accomplish the goals of sitka's emergency operations plan.
The following are potential emergencies that could affect Sitka:
Hazards which could affect Sitka
Avalanche
A growing number of people are snowboarding, riding snowmachines and cross country skiing in back country areas such as Harbor Mountain, Mt. Verstovia, Bear Mountain and Mt. Edgecumbe. Avalanches have occurred in all these areas. At present, there is no warning system in place to alert people about snow conditions and avalanche potential.
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The Blue Lake Road crosses the path of several large avalanche chutes. This road is used extensively by people in Sitka during the winter months for cross-country skiing, sledding, walking pets, and mountain biking. There is presently no advanced warning system to alert people about dangerous conditions on this road.
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Civil Disorder
Civil disorder is unlikely in the Sitka area. The greatest threat is from a possible random act of terrorism.
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Dam Failure
There is no residential community below Green Lake hydroelectric dam. Those at risk if a dam failure occurred would be people recreating on or near the lake. The road to Green Lake is closed to the public limiting the number of people with access to the area.
Located a quarter mile below the Blue Lake hydroelectric dam is a Forest Service campground. The road and campground are closed during the winter. The area is a popular walking destination and is used year round.
Catastrophic failure of these dams would result lost in hydroelectric power and potable water to the Sitka community.
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Drought
A drought in Sitka is possible but not likely.
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Earthquake
A large fault zone, the Fairweather fault, trends through the continental shelf/slope area just west of Sitka. This extensive fault zone extends from south of the Queen Charlotte Islands to the vicinity of Cordova. Movement on the fault is right-lateral, about 2.25 inches per year, which is similar to displacement along the San Andreas fault in California. A study by U.S. Geological Survey predicts that a Richter magnitude 8 or greater earthquake will occur near Sitka in the future.
The effects of a nearby major earthquake on Sitka could be serious. In Sitka, the strongest shaking will occur in muskeg, man-made fills, modern alluvial and delta deposits, and volcanic ash deposits. Less shaking is expected in beach deposits, glacial drift and bedrock.
The saturated muskeg and reworked volcanic ash would be subject to possible liquefaction during severe earthquake-caused ground shaking, and are thus unreliable as stable foundation materials.
An earthquake would also cause other disastrous events to potentially occur at the same time, including tsunamis, fires, release of hazardous materials, and energy shortages.
Energy Shortage
The possibility of an energy shortage greater than 12 hours would be the result of multiple disasters striking Sitka.
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Fire
The downtown area of Sitka is the primary site where multiple building fires could occur due to the close proximity of buildings. Fire may result from causes such as an earthquake, hazardous materials, or extreme weather. Trailer parks are another area where fire could destroy multiple structures.
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Flooding
The most probable source of flooding in Sitka is along Indian River. Homes located along the shoreline are also vulnerable from storm surges.
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Hazardous Materials
Extremely hazardous substances (EHS) are stored at the Sitka Water Treatment Plant, Seafood Producers Cooperative, Sitka Sound Seafood and the Wastewater Treatment Plant. In addition, large volumes of heating oil are also stored in downtown Sitka. These hazardous materials are transported through the most densely populated area of the community. The potential of an emergency arising from a spill or release of a hazardous material is ranked second in the hazard analysis.
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Landslides
Landslides can occur along the Blue Lake Road, Green Lake Road and powerline corridor. Landslides have occurred in the past destroying a remote section of the powerline.
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Transportation Accidents (Passengers)
Cruise ships with several thousand passengers have the potential for accidents that might result in mass casualties. A commercial plane or tour bus accident could also result in mass casualties.
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Tsunami
The coast of Alaska has a history of large waves. In Southeast Alaska, these waves include tsunamis and local waves caused by the subaerial or subaqueous landslides resulting from earthquakes and or volcanoes. Tsunami waves originating anywhere in the Pacific Ocean are potentially hazardous to Sitka. The maximum-recorded tsunami at Sitka was 7.8 feet, generated by the 1964 Prince William Sound earthquake. It has been predicted (Dames & Moore) that there is a 65% chance of a maximum wave height of at least 32 feet each 100 years at the Sitka airport. Pacific Ocean tsunamis have been recorded as high as 40 feet. Check out the tsunami preparedness page on this site.
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Volcano (Ash)
The ash that forms the bulk of Sitka soils resulted from the eruption of volcanoes on Kruzof Island about 10,000 years ago. The volcanoes are now considered dormant, as opposed to extinct. A reawakening could be very hazardous to Sitka, with widespread ash fall accompanied by gas and/or tsunami generated by an earthquake, and volcanic material entering the ocean.
Sitka also receives occasional ash fallout from active volcanoes along the Aleutian chain to the northwest. There is an adequate warning period so that preparations can occur.
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Weapons of Mass Destruction
Use of weapons of mass destruction in the Sitka community would necessitate immediate outside assistance.
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Weather Extremes
Weather extremes in this area are due to high winds, extreme high tides, extreme cold, ice storms, blizzards and occasional lightning strikes. Emergencies could arise from a combination of events.
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