. The team determined that the Rattlesnake Mountain fault zone, originally mapped by DNR geologist Tim Walsh in the 1980s, is likely the southern continuation of the southern Whidbey Island fault, extending this fault zone from the Strait of Juan de Fuca to Rattlesnake Mountain near North Bend. One model suggests it extends to about 30 miles east of Yakima. Years ago, Howard Gower and James Yount came to the Puget lowlands to study earthquake risks and stumbled on what appeared to be a fault in Island and Snohomish counties. Some parts of major cities (including Seattle, Tacoma, and Olympia) have been built on land that was reclaimed from soft and wet tidal ocean areas. We do know that it is active and will likely produce a large M67.5 earthquake when it next ruptures. Each peak of the Olympics stuck out with picturesque clarity in the distance. Why is Strange Sounds focusing so much on disaster preps? Do you know what to do if there is an earthquake? There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. It is mandatory to procure user consent prior to running these cookies on your website. An increase of 2 means that ~1,000 times more energy is released. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. Many faults have not been studied enough to know if they are active. However, seismic tomography studies (Brocher and others, 2001 #4718) reveal that only the northwestern end of the fault zone in the southeastern Strait of Juan de Fuca is associated with a strong velocity contrast. Bubbles of methane rising from seafloor in Puget Sound Experts have warned that UK outbreak may be around two weeks behind Italys. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. Close to shore, this same wave could reach heights of 30100 feet or more. Every year Western. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. The team determined that the Rattlesnake Mountain fault zone, originally mapped by DNR geologist Tim Walsh in the 1980s, is likely the southern continuation of the southern Whidbey Island fault, extending this fault zone from the Strait of Juan de Fuca to Rattlesnake Mountain near North Bend. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Some faults reach the surface and can be found by geologists. The map also shows potentially active faults from a separate 2014 report (click here to download). Photo by Steve Palmer. Even when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. Tap/click on "gear icon" for options and settings. The last major earthquake was over 300 years ago. This is an active fault.. 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. Hey Biden! What about the localized tsunami risk? Clicking on the map will download the publication. Coupeville, WA 98239, Camano Office And what were looking at is water.. The last time was 1,000 years ago between 900 and 903 A.D., said Forson. Seattle Fault - Wikipedia The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). Secure .gov websites use HTTPS Each of these aftershocks would be a significant earthquake if it happened on its own. Unlike sound, ground shaking can be amplified or attenuated (made less) depending on the type of material at the Earths surface. The spectacular falls flow over the remains of a newly discovered 20-million-year-old volcano, apparently formed atop the main part of the fault zone as magma rose upward along weak fault planes. The Cascadia subduction zone just off the Washington coast is this kind of fault and is one of the largest geologic hazards to our state. Do not exit a building during the shaking. Photo from, Liquefaction can be a big problem. Wagner and Wiley (1983 #6230) and Wagner and Tomson (1987 #6249) mapped and briefly discussed offshore parts of this fault zone and also used the name "southern Whidbey Island fault." Once in the open, Drop, Cover, and Hold On. @\;L;=}%FC*l $@ 4x: 888O~xrsxx'/*rGRF\gI%~x(G-^-hjjq kx/V ou0hyegy0;ei`Tx&ilZ )TmZ$vb,`bQm|DR5x/ People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). Disoriented drivers wonder whats wrong with their cars, then realize something much bigger is amiss. And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. These aftershocks can last for hours to weeks or months. Never use a lighter or match near damaged areas. And being ready means being able to support yourself, your loved ones, your neighborhood for 2 weeks. Faults can also occur within a tectonic plate when the plate itself is deforming. An earthquake occurs when rock inside the Earth moves or breaks. Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. Paleoseismologists have found places that record many of these tsunami deposits. Seconds later, its as if Whidbey Island is trapped in a cocktail shaker, lurching back and forth. Johnsons curiosity changed the course of his career. The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. 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. Johnson and others (1996) have described the southern Whidbey Island fault ( figure 1) as a broad (6 - 11 km) transpressional zone comprising three main splays, within which the local late Quaternary uplift rate is at least 0.6 mm/yr. Because after a region-wide event, it could take that long for help to come from the rest of the country and world. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. The Cascadia subduction zone last ruptured over 300 years ago on January 26, 1700. It could also create dangerous currents and hazards to the north including Everett. As an example, parts of Seattle and certain areas of downtown Olympia are built on softer ground that will amplify ground shaking during an earthquake. Consider whether earthquake insurance is right for you. Expect aftershocks. A .gov website belongs to an official government organization in the United States. Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. The Darrington-Devils Mountain fault zone is located in southern Skagit County and northern Snohomish County. The most important thing you can do before the next earthquake is to prepare. Contact Us, Whidbey Office South Whidbey fault has potential for major quake Along the coast residents may have between 20 and 30 minutes to get to higher ground. The Flying Squirrel and Mountain Beaver trenches cross the Cottage Lake lineament. The experts say few are ready. This means that a tsunami made by an earthquake on the Cascadia subduction zone will start to impact the Washington coast in less than 15 minutes. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. Another piece can be seen under the elevated lanes of northbound Interstate 5 in South Seattle not far from the Rainier brewery. This video from the 2011 Tohoku subduction zone earthquake shows the earthquakes before, during, and after the main M8.7 event on March 11 (at 1:50 in the video). Puget Sound Earthquake Faults - Seattle Earthquake Faults Information from seismic-reflection profiles, outcrops, boreholes, and potential field surveys is used to interpret the structure and history of the southern Whidbey Island fault in the Puget Lowland of western Washington. Another big one is expected, and it could be devastating. 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. Whidbey fault quake potentially a bigger 'Big One' Quaternary Fault and Fold Database of the United States - USGS In the late 1960s, speculators considered the Puget Sound region a frontier for petroleum exploration. Drop to your hands and knees. Scientists are not sure how far east it goes. An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. One model suggests it extends to about 30 miles east of Yakima. It startled Johnson that such massive faults had gone undetected for so long. The Seattle Fault is also likely to create a tsunami that would inundate Harbor Island and much of SODO, Interbay, and the waterfront. This map shows different seismic design categories that correlate with amount of seismic risk. Faults are features in the Earths crust where rock periodically breaks and moves, releasing seismic energy and creating an earthquake. Many universities and other organizations (such as Cascadia Region Earthquake Working Group and the Pacific Northwest Seismic Network) also work to understand active faults in Washington. Camano Island, WA 98282, Mailing Address This category only includes cookies that ensures basic functionalities and security features of the website. The height difference likely was caused by a 7.5 magnitude earthquake on the fault about 2,700 years ago, Sherrod said. The term active can have different meanings. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. Mudslides. In 1985, with little concrete evidence of its existence, the pair included the possible fault on a geologic map published by the USGS. The study of seismic waves is called seismology and has allowed scientists to learn much about the internal structure of the Earth. The affiliate sales will help us to continue the hard work we are putting in this website. This means that the internet, your cell phone, grocery stores, and gas stations may also not work. The Cascadia Subduction Zone (also known as the CSZ) is a 700-mile long fault zone located off the western coastline of British Columbia, Washington, Oregon and northern California. You can look at different geological hazard mapson the website of the Department of Natural Resources. There are also many faults that have not been studied enough to know if they are active. The key, Sherrods group would discover, was buried on Whidbey Island under layers of mud, peat moss and decaying marsh grass in the murky tidal waters at Crockett Lake, alongside the Coupeville ferry dock. The friend obliged. southern Whidbey Island fault zone (Class A) No. HOLOCENE FAULT SCARPS AND SHALLOW MAGNETIC ANOMALIES ALONG THE SOUTHERN WHIDBEY ISLAND FAULT ZONE NEAR WOODINVILLE, WASHINGTON By Brian L. Sherrod1, Richard J. Blakely2, Craig Weaver1, Harvey Kelsey3, Elizabeth Barnett1, and Ray Wells4 1 U.S. Geological Survey, Dept. Each year we map additional areas and learn more about existing faults and (or) discover new ones. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. M 7.4 Scenario Earthquake - Southern Whidbey Island fault-southern Overview Interactive Map Regional Information Impact ShakeMap Technical Origin Download Event KML Earthquakes Hazards Data & Products Learn Monitoring Research M 7.4 Scenario Earthquake - Southern Whidbey Island fault-southern 2017-05-12 20:14:09 (UTC) 48.036N 122.452W An official website of the United States government. Plate Tectonics | Pacific Northwest Seismic Network It is a qualitative scale that ranges from IXI (1-11) and measures the amount of damage caused by an event. Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. Across the northern portion of Bainbridge Island, light radar or lidar images taken from airplanes clearly show the Seattle Fault running right on the surface. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. The Seattle fault is a good example of a fault that is mostly reverse. Floods. Restoring tap water to some homes could take over a year. They didnt recognize the significance of what they found. For more information about earthquakes, faults, and emergency preparation, consider visiting the following sites: This map shows areas of seismic risk from high (red) to low (grayish-green). This map of gravity residuals measured over the puget lowland reveals a pattern of deep, fault bounded basins (cool colors) and uplifts (warm colors). Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. Tsunamis are a common result of large earthquakes in Washington. In the Pacific Northwest we use the term shallow to talk about faults and earthquakes less than 18 miles deep. A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) Rogers Belt (Mount Vernon Fault/Granite Falls Fault Zone) Cherry Creek Fault Zone Rattlesnake Mountain Fault Zone Seattle Fault Tacoma Fault Saddle Mountain Faults Mapping along the Snoqualmie River valley also helped answer the important question of where the Seattle fault lies east of its last mapped position near Issaquah. Stop as quickly as safety permits and stay in the vehicle. While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. 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. Along the water at Cama Beach State Park, cabins on a bluff overlook Saratoga Passage, facing the general direction of Lake Hancock on Whidbey Island. They knew something was there, said Sam Johnson, a retired USGS geologist who would follow up on their work. Earthquakes. Earthquakes, tornadoes, hurricanes, pandemics, too many people think it cant happen to them and they still think that they can still make a quick run to Walmart to pick up enough to last for 2-3 days and then the govt. Source: United States Geological Survey. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. Tsunami waves can travel over 500 miles per hour in the open ocean. Small fires are the most common hazard after an earthquake. Using the stratigraphic column from the Freeport quadrangle map, confirm that you can recognize . What are the most dangerous fault lines for Seattle? This means that when the Seattle fault ruptures the south side of the fault moves up relative to the north side. Geologists have used the location of these shallow, intermediate, and deep earthquakes to learn about subduction zones throughout the world. This fault zone was originally named the Devils Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. A baristas hand hovers over the bean grinder. Black lines are trace projections of the South Whidbey Island Fault, Seattle Fault Zone, and Tacoma Fault Zone faults and the N-S Hood Canal and Puget Sound faults of S. Y. Johnson et al. Please visit our Geologic Information Portal and Geologic Hazard Maps page for the most up-to-date listing of all of our hazard maps. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). The fault's length depends on whom you ask, Sherrod said. If a large earthquake happens, be prepared for many more earthquakes. After the earthquake, many things you count on may not be available. This date was confirmed by records in Japan of an orphan tsunami and by many lines of geologic evidence. 12201 Sunrise Valley Drive Reston, VA 20192, Region 2: South Atlantic-Gulf (Includes Puerto Rico and the U.S. Virgin Islands), Region 12: Pacific Islands (American Samoa, Hawaii, Guam, Commonwealth of the Northern Mariana Islands), The southern Whidbey Island fault: An active structure in the Puget Lowland, Washington, S. Y. Johnson, C. J. Potter, J.M. Liquefaction is when wet soil or sediment loses strength because it is being shaken during an earthquake. Ready to retrofit? % For some active faults, such as the Seattle fault or Cascadia subduction zone, we can also learn how often large earthquakes have happened in the past. Later movement on this long-term active fault zone cut the volcano. For example, the DNR team found evidence that the rocks creating Snoqualmie Falls are much younger than previously thought. One of the most important new technologies for finding faults (and landslides too) is called lidar. The biggest one is called the South Whidbey Island fault, and it's thought to run from Victoria, B.C., through Woodinville and possibly beyond. A normal fault occurs when two blocks are pulled away from each other. The years have gone by. All Rights Reserved 2021, Site Disclaimer In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. A lock () or https:// means youve safely connected to the .gov website. Someone screams. Both of these things can cause equal or greater damage than the actual earthquake. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). Earthquake Hazard Maps | Sound Seismic At the Washington Geological Survey, active means that a fault has evidence for movement within the Holocene time period (since about 12,000 years ago). Identify and secure items in your home or work that could cause damage. The next earthquake is inevitable, but the variability makes it difficult to know exactly when. The San Andreas in California, for example, left gaping scars in the Earths crust, at the surface. Ground shaking is a hazard near the epicenter of an earthquake and also in areas far from the earthquake where amplification occurs. Evacuate to higher ground if you are near a large body of water. The process of breaking and moving rock releases a large amount of energy that travels through the Earth as seismic waves. Some events appear to be only 200 years apart, and others are more than 1,000. Scientists have also dated large underwater landslides and turbidites that travel from the continental edge far out into the ocean basin. It can also make landslides that are much bigger than expected. Cover your head and neck with your arms to protect against falling debris. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. Share sensitive information only on official, secure websites. After the shaking stopped the sand regained its strength. Deformed recessional outwash deposits and Holocene deposits were exposed; three unconformities separated the units. Proceed cautiously once the earthquake has stopped. These cookies will be stored in your browser only with your consent. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. Make an emergency response plan for you and your family. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. This fundamental tool for earth scientists, maps show map units, faults and folds, cross sections, and other regional or local features, depending on map scale. The Richter scale was developed in southern California in 1935 and was based on the local ground motion. endobj Thats why were pushing for a lot of vertical evacuation structures to be built hotels or schools, because its not an easy problem to solve, he said. We work closely with the Washington Emergency Management Division, the Washington Seismic Safety Committee, and the Federal Emergency Management Agency to ensure that the best-available science is used in the development of hazard mitigation plans. Kelsey and others (2004 #7651) suggest that the earthquake resulted in 2.5 m uplift of the salt marsh on the north side of the fault strand relative to the marsh on the south side; no fault scarp has been identified between the marshes. But it didnt. When a fault with vertical movement ruptures the ocean floor, it lifts up part of the ocean. South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . ?7) and represents a potential seismic hazard to residents of the Puget Lowland. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. Earthquakes cause damage by moving and shaking the ground, sometimes for several minutes. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. The shaking can damage or destroy buildings and other infrastructure. 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. The medic said colleagues were becoming sick and emotionally overwhelmed The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. The southern Whidbey Island fault should be considered capable of generating large earthquakes (Ms ?? If everyone tries to use their cell phones, it can overload the system. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. Electricity, water, natural gas, and phones may not work. Southeast Extension of the Southern Whidbey Island Fault The southern Whidbey fault is unlike more visible faults on the West Coast. Once a fault is located, it is important to know if it is active. Puget Sound faults - Wikipedia Official websites use .gov Washington State Earthquake Hazard Map. Official websites use .gov Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. When earthquakes occur on faults that reach the Earths surface, the ground may rupture. Dishes jitter off tables, shattering on the floor. Areas like these are also susceptible to liquefaction. Emergency Management Maps - Island County, Washington Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. Earthquakes on faults like these may cause tsunamis in the Puget Sound region. Save my name, email, and website in this browser for the next time I comment. Surface Geology | WA - DNR Roads, bridges, or ramps may have been damaged by the earthquake. View of the Sunset Lake liquefaction failure about three weeks after the earthquake. South Whidbey Island Fault Earthquake Scenario: 7.4 Magnitude Buildings Damaged: 320,776 Fatalities: 90 - 432 Injuries: 2,920 - 7,361 Economic Loss: $15,590,000,000 SeaTac Fault Earthquake Scenario: 7.2 Magnitude Buildings Damaged: 375,954 Fatalities: 16 - 123 Injuries: 1,394 - 3,404 Economic Loss: $13,400,000,000 Tacoma Fault . PO Box 5000 All faults, regardless of size, can be dangerous if they rupture. 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. But opting out of some of these cookies may affect your browsing experience. These and other problems led to the search for a scale that was based on the physical processes that happen during an earthquake. Some of these faults are in remote areas. 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. 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. The coast is now the home of one of the states largest network of warning sirens called All Hazard Alert Broadcast (AHABs). When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System).