Local Hazards

Bainbridge Island is vulnerable to a number of natural and human caused hazards. Specific information about each hazard is detailed on the tabbed pages below. This information has been derived from several documents, including the Kitsap County Multi-Hazard Mitigation Plan, the Kitsap County Hazard Identification and Vulnerability Assessment, and a more recent FEMA produced Risk Report. Data sets for the projected structural earthquake loss, projected structural landslide loss, and projected 1% flood loss were provided by FEMA as well and are available for download on those respective hazard pages. Full versions of each of the documents listed above are available for review via the links below:

FEMA Risk Report (PDF)

Kitsap County Multi-Hazard Mitigation Plan (PDF)

Kitsap County Hazard Identification and Vulnerability Assessment (PDF)

  1. Earthquakes
  2. Tsunami and Seiche
  3. Landslide
  4. Flood

An earthquake is the motion or trembling of the ground produced by sudden displacement of rock, usually within the upper 10-20 miles of the Earth's crust. Earthquakes result from crustal strain, volcanism, landslides, or the collapse of underground caverns. Kitsap County is vulnerable to earthquakes due to its location in the Puget Sound region, which features numerous seismogenic geologic faults. Since 1962, earthquakes have had the greatest impact of any hazard on the county in terms of monetary costs and disruptions to daily life. The Nisqually earthquake of 2001 was the most recent earthquake event that caused significant damage to Kitsap County and the Puget Sound region.

Kitsap County is vulnerable to subduction as well as to fracture faults. The County lies within Seismic Risk Zone 3, which requires buildings to be designed to withstand major earthquakes measuring 7.5 in magnitude. It is anticipated, however, that earthquakes caused from subduction plate stress in the region could reach a magnitude greater than 8.0. The Seattle fault is recognized as a significant seismic hazard; evidence has indicated that it was the cause of a major 7.0 magnitude earthquake approximately 1,100 years ago (Haugerud, 2009). The potential effects of a comparable 7.2 magnitude earthquake were modeled for the Seattle Fault zone by the Washington State Department of Natural Resources (WADNR). The scenario predicts that thousands of injuries and fatalities would occur throughout the region, and thousands of buildings would collapse or be in imminent danger of collapse.

There would also be a significant number of building losses, with damage totaling $3.6 billion in Kitsap County (WADNR, 2012-2013).The effects of a major earthquake in Kitsap County would be catastrophic. Hundreds of residents could be injured or killed, and a multitude of others would be left homeless. Depending on the time of day and time of year, a catastrophic earthquake could cause hundreds of injuries and deaths and millions of dollars in critical infrastructure and private property damage (WADNR, 2012-2013). A severe earthquake could level or severely damage older buildings, especially those constructed of non-reinforced masonry.

Newer structures, which were built under recent building codes, would probably sustain less damage, but would remain vulnerable to the soil conditions of the building site. A severe earthquake would also cause major damage to County and City utilities. The most current projected structural earthquake loss data can be accessed here.

Click on the image below to view local fault lines.

Cascadia fault


Kitsap County Risk Report, Kitsap County Multi-Hazard Mitigation Plan, City of Seattle Office of Emergency Management