Graphic from IRIS. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. 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. A normal fault occurs when two blocks are pulled away from each other. He said scientists have known about the southern Whidbey fault for decades. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. DO NOT get in a doorway. Once the shaking has stopped, exit the building if it is safe to do so. Were working on pedestrian evacuation maps that show the best routes for pedestrians to take to evacuate, said Forson. The boundary between the two plates covers a large area and can lock together. The 2011 Tohoku earthquake in Japan occurred on this type of fault and released enough energy to slightly change the Earths axis of rotation. Since about 1870 there have been about 15 large earthquakes (greater than M5) in the state. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. Lidar maps show the Earths surface without vegetation. 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. The bluff, where the cabins now sit, could have jutted up in the most recent Whidbey fault quake, Sherrod said. Part 2 will be full Martial Law and mandatory vaccines? That could spell trouble not only for its namesake island but for south and north King County and further west. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. We do know that it is active and will likely produce a large M67.5 earthquake when it next ruptures. 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. This averages to ~660 to 525 years between events, but there is a lot of variation. These faults and earthquakes occur in oceanic crust as it is subducted beneath the continent. The next earthquake is inevitable, but the variability makes it difficult to know exactly when. But quiet period wont last, Strongest earthquake in 40 years rattle residents of Buffalo, NY, Is Istanbul next? This is called liquefaction and is discussed in the next section. After the shaking stopped the sand regained its strength. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Theres a must-see documentary film called Cascadia The Big One that exposes whats currently going on in this region of the Cascade volcanoes and the Pacific NorthWest. Large earthquakes are less common but can cause significant damage to the things we count on in everyday life, such as buildings, roads, bridges, dams, and utilities. Many faults have not been studied enough to know if they are active. Still think well avoid Gods wrath, its not going to happen regardless of what the multi millionaire TV preachers tell you. Scientists at the Washington Geological Survey, the U.S. Geological Survey, universities, and many private geologic consulting firms work diligently to understand how often earthquakes happen on various faults throughout Washington. Photo from https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. If the epicenter is Everett, the SWIF could cause. 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." The material becomes so weak that it behaves more like a liquid than a solid. An earthquake occurs when rock inside the Earth moves or breaks. The average time between large earthquakes is about 535 years, but has been as little as 200 years, and more than 1,000 years. Tsunamis triggered by earthquakes usually require at least a M7 event. If a large earthquake happens, be prepared for many more earthquakes. STAY THERE until the shaking stops. SWIF ranges from 12 miles underground at its deepest to right at sea level in a few scattered spots, like Cama Beach, Holmes Harbor and Woodinville, according to Sherrods research. Photo from Pacific Northwest Seismic Network Seismo Blog. Along the coast residents may have between 20 and 30 minutes to get to higher ground. Earthquakes on shallow faults typically last 20 to 60 seconds and the shaking is localized to the general area of the fault. Floods. The years have gone by. People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. It could also create dangerous currents and hazards to the north including Everett. Save my name, email, and website in this browser for the next time I comment. An earthquake can be a scary event. So I think it is worth your time to learn more about the biggest seismic riskss and major fault lines criss-crossing this part of the Pacific Northwest, namely: Now lets visit the 3 most dangerous earthquake faults for Seattle one by one: The Cascadia Subduction Zone is a giant fault running from Cape Mendocino, Calif. past Oregon and Washington and doesnt end until its north of Vancouver Island in Canada. The South Whidbey Island Fault is also dangerous. 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 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. Like a sonogram, the seismic surveys allowed Johnson to see outlines of massive fissures in the earths crust. So they dont necessarily know the threats they face.. Another big one is expected, and it could be devastating. This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. Radiocarbon dating and other paleoseismic methods have also confirmed this date. Sherrod shrugged his shoulders. Roads, bridges, or ramps may have been damaged by the earthquake. Do you live or work near an area that could have liquefaction? Under a scenario played out in a 2019 U.S. Department of Homeland Security study, state-maintained bridges would be severely damaged, leaving them unusable for months or years. This might include flammable appliances like a water heater, tall items like book cases, or heavy pictures. Small talk stops. A pair of scientists with the U.S. Geological Survey first theorized that a fissure between two major blocks of the earths crust might run through this slice of Puget Sound. 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. Most are too small to be felt or cause damage. Geologic maps of 7.5-minute topographic quadrangles covering parts of the Seattle fault and southern Whidbey Island fault zone are available on the DNR website as: Sign-up for DNR enewsletters. One or possibly two of the unconformities are interpreted as event horizons. HomePrograms and ServicesGeologyGeologic Hazards. Armentrout, J. J. Miller, C. Finn, C. S. Weaver. Notice the Seattle Fault Zone bounding the Seattle Basin to the south. In Washington, we do not have tsunami walls. Official websites use .gov America is going to be punished just like the rest of the world. Avoid stopping near or under buildings, trees, overpasses, or utility wires. Reverse faults are usually steep and occur in regions of compression. . There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. Theres approximately a 14% chance of another approximately M9 earthquake occurring in the next 50 years. Other types of seismic energy (S waves) also travel through the earth, but they move with a side-to-side (shearing) motion. When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. The buildings sank when ground shaking weakened the underlying sediments. By sampling sediment from the marsh to the beach berm, Sherrod and his research partner, Harvey Kelsey, developed a timeline of the oceans climb. 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. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. What are the most dangerous fault lines for Seattle? However, we can learn which faults are active and which are inactive. Small fires are the most common hazard after an earthquake. Johnson and others (1996 #4751) described multiple sub-parallel strands and referred to the overall structure as the "southern Whidbey Island fault zone," and this name is also used herein for this zone of faults that crosses the southern part of Whidbey Island. The process of breaking and moving rock releases a large amount of energy that travels through the Earth as seismic waves. The fault, not so much. Other faults are inactive and are left over from much older periods of deformation. This means that the internet, your cell phone, grocery stores, and gas stations may also not work. The Seattle fault is a good example of a fault that is mostly reverse. Tap/click on "gear icon" for options and settings. 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 This diagram shows the many types of active faults and the general location of past earthquakes in Washington. <>>> But Forson says you also need to know what to do when the shaking happens. Some residents may lose housing temporarily or permanently. (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. Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System). The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. Please visit our Geologic Information Portal and Geologic Hazard Maps page for the most up-to-date listing of all of our hazard maps. The San Andreas in California, for example, left gaping scars in the Earths crust, at the surface. Some events appear to be only 200 years apart, and others are more than 1,000. An official website of the United States government. These sediments were laid down 20,000 to 60,000 years ago, before the last ice age. Areas like these are also susceptible to liquefaction. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. Beef Barley and French Onion trenches cross the Little Bear Creek lineament. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. 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. 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). PI22343). Once a fault is located, it is important to know if it is active. Landslides can be caused by strong ground shaking during an earthquake. This map is from a 2007 report on the seismic design categories in Washington. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. The southern Whidbey Island fault should be considered capable of generating large earthquakes (Ms ?? 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. Tohoku killed nearly 16,000 people; most died as a result of drowning or being crushed in the tsunami. Map Releases; Topographic (Topo) Maps; Volcanic Maps; All Maps; Multimedia Gallery. Power could be out for days. The most important thing you can do before the next earthquake is to prepare. The combination of all of these effects is what makes earthquakes such a powerful geologic hazard. But they didnt document it hardly at all.. Also issued a warning for the UK that the Italian chaos could come to Britain Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. A .gov website belongs to an official government organization in the United States. and the Red Cross will be there to care for them. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). The map is from a 2007 report (click here to download) on seismic design categories in Washington. The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. Scientists have also dated large underwater landslides and turbidites that travel from the continental edge far out into the ocean basin. This fault will have an earthquake in the future, but we cannot predict exactly when. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. But it didnt. People are already fighting over toilet paper, just imagine what will it be like when they go shopping for food and the shelves are almost empty. Each of the earthquakes listed on the bottom of the screen is capable of significant damage. The San Andreas fault in California is a good example of a very active strike-slip fault. You saw its potential in the 9.1 magnitude Tohuku earthquake and tsunami that hit northeastern Japan in March 2011. Washington has the second highest risk in the U.S. of these large and damaging earthquakes because of its geologic setting. Although both seiches and tsunamis can be large and destructive, they are created differently. In fact, new faults are found every year during our geologic mapping efforts. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Earthquakes occur nearly every day in Washington. It will happen; we dont know when.. 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. . The Geologic Information Portal has a Natural Hazards theme that shows active faults and earthquakes. 572 Last Review Date: 2016-11-29 Facades crumble off buildings along Oak Harbors Pioneer Way, and some of the oldest structures in Langley and Coupeville collapse in a roaring cloud of dust. Why is Strange Sounds focusing so much on disaster preps? There are also many faults that have not been studied enough to know if they are active. In 2017, he began studying the possible aftermath of a major SWIF quake. Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. Geologists have used the location of these shallow, intermediate, and deep earthquakes to learn about subduction zones throughout the world. 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. These aftershocks can last for hours to weeks or months. Drop to your hands and knees. Transpressional deformation along the southern Whidbey Island fault is indicated by alongstrike variations in structural style and geometry, positive flower structure, local unconformities, out-of-plane displacements, and juxtaposition of correlative sedimentary units with different histories. The video is also available in Spanish and there is a fun activity/coloring book that can be found here. Because Japan was so well prepared, mostretrofitted buildingsoutside of the tsunami zone survived. This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. Coupeville, WA 98239, Main Line: (360) 678-5111 Most damage and loss of life in earthquakes is a result of ground shaking. The French Onion trench exposed glaciolacustrine claystones, till, colluvial deposits, and Holocene soils. The marshy deposits are about a meter higher at Lake Hancock. What makes these faults mega is that the amount of energy released is hundreds to thousands of times more than almost any other type of fault. of Earth and Space Sciences, Box 351310, Univ. Theyre FREE CLICK HERE to subscribe, EAR TO THE GROUND WITH DNR & COMMISSIONER FRANZ, Tree Link helps you answer questions about urbantrees.

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