Learn how your comment data is processed. People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. California Department of Conservation. PDF Cretaceous-Jurassic accreted terrains - University of Washington Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. If the epicenter is Everett, the SWIF could cause. Also, very large earthquakes were difficult to measure accurately. , * NOTE: Hazard maps for each jurisdiction will only be included if that jurisdiction is at risk to that hazard., Copyright Island County. Earthquake Hazards - Maps | U.S. Geological Survey Notice the Seattle Fault Zone bounding the Seattle Basin to the south. Photo courtesy of MOHAI (neg. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. There are also many faults that have not been studied enough to know if they are active. (1996) used seismic-reflection profiles in Puget Sound near Whidbey Island, sea-cliff exposures on Whidbey Island, and sparse borehole data to map and interpret the SWIF as a broad fault zone (6 to 11 km wide) dipping steeply to the northeast. Emergency Management Hazard Maps - Island County, Washington Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. Because they rupture at such great depth, their seismic energy is distributed over a large area. The moment magnitude scale replaced the Richter scale in the late 1970s. Sometimes there may be a layer of volcanic ash or charcoal that has been deformed by the fault. Cover your head and neck with your arms to protect against falling debris. 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. Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. On an inactive fault, the sea would have risen at the same rate at both locations. The southern Whidbey Island fault should be considered capable of generating large earthquakes (Ms ?? 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. Plate Tectonics | Pacific Northwest Seismic Network Photo by Steve Palmer. These cookies will be stored in your browser only with your consent. For example, it is unlikely that you will be able to use electricity, cell phones, or the internet. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. The moment magnitude scale is a type of logarithmic scale, where each increase of 1 means ~32 times more energy is released. Know what to expect. There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. North Anatolian Fault is currently locked, accumulating stresses which could be suddenly released anytime now like the Hayward Fault in California, Videos: New destructive M7.5 earthquake hits Turkey a few hours after largest quake in 100 years kills 1300. . 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). Over time, fault movement has created some interesting geologic features. The map also shows potentially active faults from a separate 2014 report (click here to download). You will not be able to google what to do in an earthquake when it is happening. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. PDF Seismic Characterization of the Seattle and Southern Whidbey Island <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Know what other hazards you might face. Whidbey fault quake potentially a bigger 'Big One' The southern Whidbey Island fault divides the two. In the early 2000s, USGS scientists including Brian Sherrod set out to further Johnsons work and better understand the slumbering fissure. These aftershocks can last for hours to weeks or months. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. Jump from 60 to 600 per week in just 5 years in Pahala, Is the Cascadia Subduction Zone about to blow? This is similar to how sound is quieter when you move away from a speaker. A drill rig left of the blockade is collecting data about the failure. We do know that it is active and will likely produce a large M67.5 earthquake when it next ruptures. Keaton and Perry (2006 #7653) excavated two trenches on the south end of the Brightwater treatment plant (KP1 site 572-3, and KP2 site 572-4). 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. Ready to retrofit? ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. The southern Whidbey fault is shallow, running right under Snohomish County as opposed to many miles off shore like the Cascadia fault. 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. Geologists do not yet know how often earthquakes happen on this fault. Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System). Oil companies descended in search of riches. The Seattle Fault is also likely to create a tsunami that would inundate Harbor Island and much of SODO, Interbay, and the waterfront. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. Story telling is an important part of the Native tradition and is how their history is passed down to the next generation. This fault zone was originally named the Devils 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. Its a natural curiosity.. One of the best views of SWIF should be from Grand Avenue Park in Everett. Evacuate to higher ground if you are near a large body of water. Some faults reach the surface and can be found by geologists. The southern Whidbey Island fault zone (SWIF), as previously mapped using borehole data, potential field anomalies, and marine seismic reflection surveys, consists of three subparallel, northwest trending strands extending ~100 km from near Vancouver Island to the northern Puget Lowland. The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). America is going to be punished just like the rest of the world. ShakeMapGeologicSummaries - University of Washington And when are documentary film called Cascadia The Big One, Dangerous Inland Earthquake Destroys Homes and Schools near Jakarta, Indonesia, Terrifying video shows olive grove turned into a Gigantic Canyon after Turkeys earthquake split land in huge rifts. Until much more recently, no one really understood what it could do to a region of over 4 million people. Its just the way scientists work, he said. A small quake was registered in the Coupeville area just this summer. South Whidbey Island Fault Zone. Most damage and loss of life in earthquakes is a result of ground shaking. The team also found that accumulated movement on the fault has uplifted old Snoqualmie River sediments to their current position on ridges, in some places several hundreds of feet above the modern Snoqualmie valley floor. The Safe America Foundation suggests texting as a way of communication. What scientists dont know is its timing interval. EVERETT The South Whidbey Island Fault is connected to a system of powerful earthquake fault lines stretching from Victoria, B.C., to Yakima that is capable of unleashing a devastating. Tsunamis are a common result of large earthquakes in Washington. Johnsons curiosity changed the course of his career. Puget Sound faults - Wikipedia Evidence for Quaternary movement on the southern Whidbey Island fault includes (1) offset and disrupted upper Quaternary strata imaged on seismic-reflection profiles; (2) borehole data that suggests as much as 420 m of structural relief on the Tertiary-Quaternary boundary in the fault zone; (3) several meters of displacement along exposed faults in upper Quaternary sediments; (4) late Quaternary folds with limb dips of as much as ???9?? Washington, Seattle, WA 98195 2 U.S. Geological Survey, 345 Middlefield Road, M/S . A thrust fault is a special kind of reverse fault that has a shallow dip. % This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. And experts fear it could be even worse than The Big One.. Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. When the landslide hit the water it may have created a tsunami. STAY THERE until the shaking stops. The northwest-trending southern Whidbey Island fault zone occurs along a significant terrane boundary between basement blocks underlain by Eocene marine basalts of the Coast Range province to the southwest and pre-Tertiary metamorphic rocks of the Cascades province to the northeast. The SWIF has been assessed by the USGS as capable of generating the largest crustal earthquake in Puget Sound. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. The average time between large earthquakes is about 535 years, but has been as little as 200 years, and more than 1,000 years. Theres an uneasy hush. Beef Barley and French Onion trenches cross the Little Bear Creek lineament. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. Stop as quickly as safety permits and stay in the vehicle. However, we can learn which faults are active and which are inactive. He said scientists have known about the southern Whidbey fault for decades. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. Save my name, email, and website in this browser for the next time I comment. Earthquakes can trigger landslides and tsunamis which can happen after the main event. If they know theres data available that could help them in any way, they want to get it. The Seattle Fault is a zone of multiple shallow east-west thrust faults that cross the Puget Sound Lowland and through Seattle (in the U.S. state of Washington) in the vicinity of Interstate Highway 90.The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about . These large underwater slides only occur during very large earthquakes and are one way to learn about earthquakes that happened thousands of years ago. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. Once a fault is located, it is important to know if it is active. These maps are created by small planes that use a specific type of laser to measure the elevation of the ground. These quakes are capable of magnitudes from 7 to over 9. Fir trees near the failure are tilted and indicate rotation into the lake (to the left of the photo). Finding and learning about faults requires many different aspects of geology and geophysics. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Quaternary Rupture of a Crustal Fault beneath Victoria, British M 7.4 Scenario Earthquake - Southern Whidbey Island fault-southern The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. Clicking on the map will download the publication. 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. The last major earthquake was over 300 years ago. 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. Maps. A paleoseismologist will look for surface ruptures along faults and may use carbon-14 dating to learn when the rupture happened. 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. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. Southern Whidbey Island Fault Zone Mapped through Snoqualmie Valley South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . A lock () or https:// means youve safely connected to the .gov website. Scientists are not sure how far east it goes. 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. Small fires are the most common hazard after an earthquake. After the shaking stopped the sand regained its strength. His team wanted to find the rate of sea level rise along the shore. Camano Island, WA 98282, Mailing Address Map by And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. We pray for people of WA and our all north Americans as well. Official websites use .gov Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. Unlike The Big One, scientists who have studied the southern Whidbey fault have far less understanding of when the next sudden shift might hit. 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. One model suggests it extends to about 30 miles east of Yakima. Lidar maps show the Earths surface without vegetation. Washington has few large normal faults because it is mostly in a region of compression. Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. This is called liquefaction and is discussed in the next section. The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. . 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. endobj Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. The Darrington-Devils Mountain fault zone is located in southern Skagit County and northern Snohomish County. PDF Modeling a Magnitude 7.4 Earthquake on the Southern Whidbey Island Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. Identify and secure items in your home or work that could cause damage. Also issued a warning for the UK that the Italian chaos could come to Britain All Rights Reserved 2021, Site Disclaimer The Survey conducts and publishes geologic mapping to identify and characterize faults throughout the state. 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. Trenches by Sherrod and others, 2008 #7652) are less than 1 km south of KP1 and KP2 and Sherrod and others (2008 #7652) conclude that deformation in the area is due to surface-rupturing earthquakes. The best thing you can do is to become prepared. The western half of Washington state is considered earthquake country, with the potential for very large quakes. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. Geoscientist Brian Sherrod stands near the submerged southern Whidbey Island fault line at the Brightwater Treatment Plant in Woodinville. They knew something was there, said Sam Johnson, a retired USGS geologist who would follow up on their work. And being ready means being able to support yourself, your loved ones, your neighborhood for 2 weeks. In fact, new faults are found every year during our geologic mapping efforts. Like other faults, when enough stress builds up, the megathrust will rupture. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. This might include flammable appliances like a water heater, tall items like book cases, or heavy pictures. 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. Puget Sound Earthquake Faults - Seattle Earthquake Faults The faults length depends on whom you ask, Sherrod said. 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. Scientists are not sure how far east it goes. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault The Seattle fault is a good example of a fault that is mostly reverse. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. 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. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. Each of these aftershocks would be a significant earthquake if it happened on its own. HomePrograms and ServicesGeologyGeologic Hazards. Surface Geology | WA - DNR 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. It is not yet possible to predict when a fault will have an earthquake. When an earthquake happens there will not be time to google what you are supposed to do. 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. Even places that are far from active faults are still at risk during a large Cascadia subduction zone earthquake. On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. %PDF-1.5 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. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Everything points to one thing, Sherrod said, waving his hand across the inland sea. This means that a large area feels the shaking, but the intensity is less than a similar shallow earthquake. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. Sherrod shrugged his shoulders. These differences are related to the overall pattern of stress in the crust, what types of rocks the crust is made from, and how many faults there are. 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. In Washington, we do not have tsunami walls. Roads, bridges, or ramps may have been damaged by the earthquake. Seattle Fault - Wikipedia Seismic waves travel at hundreds to thousands of miles per hour and quickly reach the surface where they are felt or measured. Dishes jitter off tables, shattering on the floor. The most important thing you can do before the next earthquake is to prepare. Depending on the type of fault, the ground can move laterally, vertically, or a combination of both. Be prepared and read more on DNR, USGS, King5, Strange Sounds and Steve Quayle. Even if the earthquake is too small to be felt by people, seismographs can detect it. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. Earthquakes occur nearly every day in Washington. Johnson and others (1996 #4751) described the structure and stratigraphy of the southern Whidbey Island fault zone. Faulting produced warping at the site of greater than 2 m. Radiocarbon ages provide a maximum age for the folding event of 12,09011,670 cal yr BP. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). Theres approximately a 14% chance of another approximately M9 earthquake occurring in the next 50 years. In effect, the wave energy is trapped by the edges of the body of water. Contact Us, Whidbey Office 552 - Hood Canal fault zone (Class B) 570 - Seattle fault zone 572 - Southern Whidbey Island fault zone 575 - Saddle Mountain faults 581 - Tacoma fault zone. This map shows areas of seismic risk from high (red) to low (grayish-green). Necessary cookies are absolutely essential for the website to function properly. Sherrod remembers his son, age 5 at the time, playing with toy trucks on the mossy banks of the marsh while the scientists worked. The trench did expose faults, but it was not possible to conclusively demonstrate offset of Holocene units. The southern Whidbey Island fault: An active structure in the Puget Though it was not directly related to Johnsons work, he asked a friend working for Mobil Oil to pass along the information. Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface.