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In 2017, he began studying the possible aftermath of a major SWIF quake. The marshy deposits are about a meter higher at Lake Hancock. Sherrod and others, 2008 #7652) report results from four trenches located near Crystal Lake: Flying Squirrel trench (572-5), Mountain Beaver trench (572-6), Beef Barley trench (572-7), and French Onion trench (572-8). Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Faults can also be grouped based on what part of the crust they occur in. A .gov website belongs to an official government organization in the United States. Scientists have used the stories from tribes along the entire Pacific Northwest coast to learn that the last large earthquake on the Cascadia subduction zone was about AD 1700. Resources on tsunami danger and preparedness in Westport, Grays Harbor County, Long Beach Peninsula, and Coastal evacuation maps. This means that when the Seattle fault ruptures the south side of the fault moves up relative to the north side. A strike-slip fault occurs when two blocks move past each other. Photo by Steve Palmer. The Mercalli Intensity scale is another historical way to measure the intensity of an earthquake. Most damage and loss of life in earthquakes is a result of ground shaking. These faults and earthquakes occur in the continental crust of North America. In Washington, the risk from earthquake-induced landslides is large. It forms the northern boundary of the Everett basin and lies along a series of high-amplitude aeromagnetic anomalies that extend from the Cascade Mountains to Vancouver Island, B.C. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. At the Brightwater treatment plant in Woodinville and at Crystal Lake in Maltby, the government researchers found telltale slopes of offset ground, known as scarps, indicative of a long-ago quake. Image from the, Aquatic Lands Habitat Restoration Program, South Lake Washington Restoration Project, Scientific and Technical Support to Aquatic Programs, Washington Geologic Survey Publications Catalog, Washington Geologic Survey Photograph Collection, Wetlands of High Conservation Value Map Viewer, Timber Sale Remaining Volume by Purchaser Reports, Spanish - Brocha, Salal y Otros Productos Forestales, Complete: Baker to Bellingham Non-Motorized Recreation Plan, Community Wildfire Resilience and Preparedness, Utility Wildland Fire Prevention Advisory Committee, Blanchard, Reiter, Walker Valley and Nearby Islands, Teanaway Community Forest Advisory Committee, Teanaway Community Forest Advisory Committee Past Meetings, Faults and Earthquakes in Washington State, Pacific Northwest Seismic Network Seismo Blog, https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg, Pacific Geoscience Center of the Natural Resources of Canada. Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. Liquefaction is when wet soil or sediment loses strength because it is being shaken during an earthquake. The Survey is working with the Office of the Superintendent of Public Instruction (OSPI) and Reid Middleton, an engineering firm, to perform seismic safety assessments of 220 school buildings across the state. And what were looking at is water.. The crustal faults the Seattle Fault, the South Whidbey Island Fault, the Tacoma Fault those are less well known, said Forson. The Westport area is now the first in North America to have acommunity vertical evacuation structure, a building strong enough to resist earthquake and tsunami wave forces and give people a platform above the expected wave heights. This part of the Japanese coast had not seen this type of seismic rupture in some 800 years, and what failed was that walls built to keep tsunami waves were not high enough. District Court: (800) 946-9765, South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario. A half dozen people reaching for the last can of soup, someone could lose their life over that. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. Seattle Fault and Whidbey Faults HAZARD MAPS As part of the Hazard Mitigation Planning process, mapping of the hazards that have the potential to affect the jurisdiction is performed using geographic information systems (GIS) software. By sampling sediment from the marsh to the beach berm, Sherrod and his research partner, Harvey Kelsey, developed a timeline of the oceans climb. Because they need large earthquakes that move the ocean floor, tsunamis are most commonly made by subduction zone faults like those found off the coasts of the Pacific Northwest, Japan, and Chile. Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. The southeastern and central parts of the southern Whidbey Island fault zone form the southwest margin of the Everett basin and northeast boundary of the Seattle basin. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). Earthquakes cause damage by moving and shaking the ground, sometimes for several minutes. Experts have warned that UK outbreak may be around two weeks behind Italys. These older faults do not have any evidence for recent activity, but the Earth is always changing. Someone screams. We do know that it is active and will likely produce a large M67.5 earthquake when it next ruptures. Subtle scarps and topographic lineaments on Pleistocene surfaces are visible on high-resolution LiDAR topography at a number of locations (Sherrod and others, 2008 #7652); the northeast-side-up scarps exhibit 15 m of vertical relief, late glacial and post-glacial sediments (Sherrod and others, 2008 #7652). Drop, Cover, and Hold On whenever you feel shaking. <> Also issued a warning for the UK that the Italian chaos could come to Britain A national credit rating service has improved its opinion of WhidbeyHealths financial future. Close to shore, this same wave could reach heights of 30100 feet or more. Johnson et al. Around Puget Sound, it seems everyone knows about The Big One, the potential magnitude 9.0 Cascadia Subduction Zone megaquake some scientists say is due any day. The southern Whidbey Island fault should be considered capable of generating large earthquakes (Ms ?? Sherrod shrugged his shoulders. . Landslide at Salmon Beach was triggered by the 1949 Tacoma earthquake and caused a tsunami. Within this rich oral history there are many references to events like earthquakes and tsunamis. This movement happens because stress builds up as tectonic plates move. The southern Whidbey Island fault (SWIF) stretches from the vicinity of Victoria, B.C., across Puget Sound as far as the Cascade Range. Gower (1980 #6229) showed and named the "southern Whidbey Island fault," and Gower and others (1985 #4725) showed this fault on their seismotectonic map of the Puget Sound region and briefly outlined its geologic relationships. As of January 12, 2017, the USGS maintains a limited number of metadata fields that characterize the Quaternary faults and folds of the United States. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. With Medical Martial Law imposed in Washington state. %PDF-1.5 In effect, the wave energy is trapped by the edges of the body of water. Even if the earthquake is too small to be felt by people, seismographs can detect it. This northwest-trending fault zone extends more than 65 km across Possession Sound, southern Whidbey Island, Admiralty Inlet into the eastern Strait of Juan de Fuca. This map shows different seismic design categories that correlate with amount of seismic risk. If folding on the Little Bear Creek lineament resulted in one or two of unconformities, the poorly constrained timing of the earthquakes is younger than 12,000 yr BP and older than about 2,850 cal yr BP. After a large earthquake it is common to have other large earthquakes for hours, days, and even weeks. Additional fault studies by state and federal geologists in the next few years will help determine the frequency and severity of earthquakes along these fault zones. The fault zone, known to geologists as SWIF, cuts through Puget Sound in a diagonal line roughly from Port Townsend to the southern tip of Whidbey Island, then to Mukilteo, Bothell, North Bend and possibly farther east below the Cascades. Each type has different kinds of earthquakes. Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. Strait of Juan de Fuca Fault Map The Puget Sound faults under the highly populated Seattle and Puget Sound region of Washington state form a regional network of interrelated seismologic geologic faults. These quakes are capable of magnitudes from 7 to over 9. An official website of the United States government. This new method allows geologists to see through trees and vegetation to find new faults. ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. This northwest-trending fault comprises a broad (as wide as 6-11 km), steep, northeast-dipping zone that includes several splays with inferred strike-slip, reverse, and thrust displacement. The buildings sank when ground shaking weakened the underlying sediments. When the landslide hit the water it may have created a tsunami. In the 1990s, scientists producedan animationthat shows inundation, and people wont have much time to run to higher ground. This website uses cookies to improve your experience while you navigate through the website. A lock () or https:// means youve safely connected to the .gov website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. You will not be able to google what to do in an earthquake when it is happening. Learn about at-risk areas and become prepared. Scientists have been trying to understand how often earthquakes happen for over 100 years.