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The Flying Squirrel and Mountain Beaver trenches cross the Cottage Lake lineament. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. The Richter scale was developed in southern California in 1935 and was based on the local ground motion. Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . You saw its potential in the 9.1 magnitude Tohuku earthquake and tsunami that hit northeastern Japan in March 2011. Southeast Extension of the Southern Whidbey Island Fault By Human Capital March 19, 2019. sw_whidbeyfault_rev122706.pdf (28.68 KB) The southern Whidbey fault is shallow, running right under Snohomish County as opposed to many miles off shore like the Cascadia fault. 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. Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface. An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. You just need one person to crash or a power line to fall over the road, and the roads are unusable.. Earthquakes can trigger landslides and tsunamis which can happen after the main event. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. Read more below to learn about how and where earthquakes occur, what to do before, during, and after an earthquake, and what scientists are doing to learn more about them. Geologic maps show the types and ages of rocks and younger deposits that are found at or near the Earth's surface. This map shows areas of seismic risk from high (red) to low (grayish-green). A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . Avoid stopping near or under buildings, trees, overpasses, or utility wires. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. PI22343). For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. Tap/click on "gear icon" for options and settings. Liquefaction can be a big problem. Each of these aftershocks would be a significant earthquake if it happened on its own. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. In this photo, visitors to Green Lake Park near Seattle, Washington, have parked their bicycles as they look at the cracks made by the April 1949 earthquake. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. We also use third-party cookies that help us analyze and understand how you use this website. For example, it is unlikely that you will be able to use electricity, cell phones, or the internet. Other faults may lie entirely underground, or could be covered by vegetation and (or) sediment. A small quake was registered in the Coupeville area just this summer. Contact Us, Whidbey Office 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. The fault, not so much. In places where there is little vegetation, different rock types and faults can be found with relative ease. Recent geologic mapping by Washington State Department of Natural Resources (DNR) geologists reveals that this major fault zone extends through the Snoqualmie River valley in the vicinity of Carnation, Fall City, and North Bend. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. 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. That may not sound like much more than the magnitude 6.8 quake of 2001 based on the numbers, but that the Nisqually quake occurred some 30 miles underground. Liquefaction has caused significant damage during earthquakes in Washington. This can cause landslides to occur where they wouldnt normally happen. One model suggests it extends to about 30 miles east of Yakima. Walsh said that Whidbey Island through the years has been subjected to a number of small quakes, roughly 2 or 3 on the Richter scale. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. and the Red Cross will be there to care for them. People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. Save my name, email, and website in this browser for the next time I comment. That could spell trouble not only for its namesake island but for south and north King County and further west. Depending on the type of fault, the ground can move laterally, vertically, or a combination of both. . The ground shaking from these earthquakes can last for several minutes. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. You will not be able to google what to do in an earthquake when it is happening. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. Earthquakes on faults like these may cause tsunamis in the Puget Sound region. A thrust fault is a special kind of reverse fault that has a shallow dip. Earthquakes occur nearly every day in Washington. A baristas hand hovers over the bean grinder. By clicking Accept, you consent to the use of ALL the cookies. Snohomish, King and Island counties would be expected to see the. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. Electricity, water, natural gas, and phones may not work. Consider whether earthquake insurance is right for you. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. What we know about this fault is that its ruptured may times in the pastit will happen again. Necessary cookies are absolutely essential for the website to function properly. 4 0 obj Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. Sheriff:(360) 679-7310, Juror Recordings 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. Visit our School Seismic Safety page for more information. Once we got it, we were sort of shocked to see these big faults in the Puget lowlands, he said. This scenario was modeled on the part of the SWIF from Woodinville to just west of Whidbey Island. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. Its certainly not to scare you. Know what to expect. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). (1999 . Geologists have used the location of these shallow, intermediate, and deep earthquakes to learn about subduction zones throughout the world. Geologists do not yet know how often earthquakes happen on this fault. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. 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. You can look at different geological hazard mapson the website of the Department of Natural Resources. When a fault with vertical movement ruptures the ocean floor, it lifts up part of the ocean. This kind of landslide is called an earthquake-triggered landslides. Early mapping of the three subparallel, northwest trending strands of the southern Whidbey Island fault zone was constrained by borehole data, potential field anomalies, marine seismic reflection surveys. The South Whidbey Island Fault is also dangerous. Some faults reach the surface and can be found by geologists. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. 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. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. 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. Learn about at-risk areas and become prepared. Within this rich oral history there are many references to events like earthquakes and tsunamis. On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. The moment magnitude scale replaced the Richter scale in the late 1970s. After the shaking stopped the sand regained its strength. % Share sensitive information only on official, secure websites. All faults, regardless of size, can be dangerous if they rupture. Some events appear to be only 200 years apart, and others are more than 1,000. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. The buildings sank when ground shaking weakened the underlying sediments. Most are too small to be felt or cause damage. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. 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. So the fault remained mostly a mystery until the 1990s. This category only includes cookies that ensures basic functionalities and security features of the website. Johnson et al. 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. Beef Barley and French Onion trenches cross the Little Bear Creek lineament. 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. Coupeville, WA 98239, Main Line: Roads, bridges, or ramps may have been damaged by the earthquake. Still think well avoid Gods wrath, its not going to happen regardless of what the multi millionaire TV preachers tell you. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. The trenches exposed glacial deposits disrupted by faults and liquefaction features. If everyone tries to use their cell phones, it can overload the system. Doctor reveals the horrors Italian medics are facing in overwhelmed hospitals where dying patients are being left untreated as experts warn UK and US are just two weeks behind Italy and the public are not SCARED enough, An intensive care doctor in northern Italy has described the scale of the crisis Restoring tap water to some homes could take over a year. An official website of the United States government. Why is Strange Sounds focusing so much on disaster preps? The Survey has developed several types of hazard maps for different types of earthquake- and fault-related hazards: The maps are used by state and local governments to develop and update hazard-mitigation and response plans, and to mark geologically hazardous areas. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. The southern Whidbey fault is unlike more visible faults on the West Coast. Bookcases and china cabinets topple, trapping people beneath. Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. The most recent hit roughly 2,700 years ago. 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. 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. Each type has different kinds of earthquakes. This is called liquefaction and is discussed in the next section. 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 trench did expose faults, but it was not possible to conclusively demonstrate offset of Holocene units. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. 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 best thing you can do is to become prepared. The continued movement along faults over millions of years can build mountains, tear a continent apart, and move tectonic plates thousands of miles. 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. Most faults are considered active if they have evidence for movement (this includes earthquakes) within the past 12,000 years (the Holocene time period). Do you know what to do if there is 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. This map of gravity residuals measured over the puget lowland reveals a pattern of deep, fault bounded basins (cool colors) and uplifts (warm colors). A strike-slip fault occurs when two blocks move past each other. In the area of North Bend, the fault zone is 4 miles wide and consists of a series of parallel faults. Lidar maps show the Earths surface without vegetation. x\[s8~OU)! 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." Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. The last major earthquake was over 300 years ago. @\;L;=}%FC*l $@ 4x: 888O~xrsxx'/*rGRF\gI%~x(G-^-hjjq kx/V ou0hyegy0;ei`Tx&ilZ )TmZ$vb,`bQm|DR5x/ A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. Share sensitive information only on official, secure websites. A team headed by Joe Dragovich of DNRs Division of Geology and Earth Resources,assisted by geologists from King County, Pacific Northwest Seismic Network, Colorado College, and Washington State University, has been mapping in this area for the past three years. Faults are features in the Earths crust where rock periodically breaks and moves, releasing seismic energy and creating an earthquake. When the landslide hit the water it may have created a tsunami. endobj It could also create dangerous currents and hazards to the north including Everett. 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. When earthquakes occur on faults that reach the Earths surface, the ground may rupture. The last time was 1,000 years ago between 900 and 903 A.D., said Forson. Resources on tsunami danger and preparedness in Westport, Grays Harbor County, Long Beach Peninsula, and Coastal evacuation maps. Washington has dozens of active faults and fault zones. If a large earthquake happens, be prepared for many more earthquakes. The affiliate sales will help us to continue the hard work we are putting in this website. After large earthquakes there are usually many aftershock earthquakes. In addition, the Survey performs seismic safety evaluations of schools. With Medical Martial Law imposed in Washington state. In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. Notable earthquakes in bold happened in Washington. Even places that are far from active faults are still at risk during a large Cascadia subduction zone earthquake. By finding the age of the deformed layer, a paleoseismologist can determine the minimum age of the fault. 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.