All Rights Reserved 2021, Site Disclaimer The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. We just dont know when.. 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. A national credit rating service has improved its opinion of WhidbeyHealths financial future. Maps. The SWIF was first recognized and mapped at a regional scale by Gower and others (1985) on the basis of gravity and aeromagnetic anomaly maps. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). His team wanted to find the rate of sea level rise along the shore. Faults can also be grouped based on what part of the crust they occur in. Earthquakes occur nearly every day in Washington. In the area of North Bend, the fault zone is 4 miles wide and consists of a series of parallel faults. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). Southeast Extension of the Southern Whidbey Island Fault, Washington: Implications for Earthquake Hazards, 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). This movement happens because stress builds up as tectonic plates move. Earthquakes occur nearly every day in Washington. Within minutes, he spotted something groundbreaking. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. In fact, new faults are found every year during our geologic mapping efforts. The map also shows potentially active faults from a separate 2014 report (click here to download). What we know about this fault is that its ruptured may times in the pastit will happen again. All faults, regardless of size, can be dangerous if they rupture. Stratigraphy and diatom assemblages of the marsh cores suggest Crockett Marsh underwent a 12 m of abrupt uplift relative to sea level at a time that relative sea level remained the same at Hancock Marsh. In Seattle, the quake damaged buildings, weakened bridges, started fires and opened cracks in the earth. Drop to your hands and knees. Notable earthquakes in bold happened in Washington. Others, like the Seattle fault and southern Whidbey Island fault zone, cross under major cities and pose a significant hazard. The combination of all of these effects is what makes earthquakes such a powerful geologic hazard. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. One or possibly two of the unconformities are interpreted as event horizons. 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. People stagger into the streets to avoid an avalanche of debris. When this happens, even a very small slope can cause the ground to slide. Photo from https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg. A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. Hover over a cluster of earthquakes to learn about the different types in the Pacific Northwest. What scientists dont know is its timing interval. Most are too small to be felt or cause damage. Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. Stay away from glass, windows, outside doors and walls, and anything that could fall down. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. Once in the open, Drop, Cover, and Hold On. You will not be able to google what to do in an earthquake when it is happening. /L\Axc4Q/w4Ks^#, sRITgZf>,e}iI5,F_ADGc?f e@L. 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. Ground shaking is a hazard near the epicenter of an earthquake and also in areas far from the earthquake where amplification occurs. The southern Whidbey Island fault (SWIF) stretches from the vicinity of Victoria, B.C., across Puget Sound as far as the Cascade Range. If you are already planning your Christmas gifts, please buy with us on Amazon. One model suggests it extends to about 30 miles east of Yakima. Learn how your comment data is processed. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. The map also shows potentially active faults from a separate 2014 report (click here to download). 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 South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . This fault produces some of the largest and most damaging earthquakes in the world (M9). Every year Western. A .gov website belongs to an official government organization in the United States. 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. For the most up-to-date information, please refer to the interactive fault map. Expect and help to extinguish fires. After the earthquake, many things you count on may not be available. For example, if there is one M7 earthquakes in an area every 1,000 years, then there will be about 10 M6 earthquakes, 100 M5 earthquakes, and 1,000 M4 earthquakes during the same 1,000 years. Never use a lighter or match near damaged areas. This date was confirmed by records in Japan of an orphan tsunami and by many lines of geologic evidence. ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. You also have the option to opt-out of these cookies. They didnt grow up here, they havent heard this story. Image from the Pacific Geoscience Center of the Natural Resources of Canada. Unlike sound, ground shaking can be amplified or attenuated (made less) depending on the type of material at the Earths surface. Everything points to one thing, Sherrod said, waving his hand across the inland sea. It is mandatory to procure user consent prior to running these cookies on your website. STAY THERE until the shaking stops. A thrust fault is a special kind of reverse fault that has a shallow dip. 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. This is sometimes called "The Big One" by news media. 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. But opting out of some of these cookies may affect your browsing experience. This earthquake caused parts of Restoration Point near on Bainbridge Island to be lifted 35 feet straight up. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. Other faults may lie entirely underground, or could be covered by vegetation and (or) sediment. This is called liquefaction and is discussed in the next section. You have entered an incorrect email address! 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. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. When the landslide hit the water it may have created a tsunami. They havent dug up enough history to estimate. 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. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. An increase of 2 means that ~1,000 times more energy is released. In 2017, he began studying the possible aftermath of a major SWIF quake. The SWIF has been assessed by the USGS as capable of generating the largest crustal earthquake in Puget Sound. Each of the earthquakes listed on the bottom of the screen is capable of significant damage. This means that when the Seattle fault ruptures the south side of the fault moves up relative to the north side. Coupeville, WA 98239, Camano Office Within this rich oral history there are many references to events like earthquakes and tsunamis. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. Superior Court:(800) 254-2755 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. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. But the Cascadia Subduction Zone isnt just a fault; its an overlapping joint between tectonic plates, parts of the Earths crust that float on layers of molten rock. Using the stratigraphic column from the Freeport quadrangle map, confirm that you can recognize . Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. These faults and earthquakes occur in oceanic crust as it is subducted beneath the continent. 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. 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. . The process of breaking and moving rock releases a large amount of energy that travels through the Earth as seismic waves. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. The fault's length depends on whom you ask, Sherrod said. The Port of Coupeville will apply for a grant to fund two electric vehicle charging stations. A baristas hand hovers over the bean grinder. Theres a reason the lands around the Pacific Ocean are called the Ring of Fire. The earthquakes, tsunamis, and the proximity of volcanos are all part of the same system. The video is also available in Spanish and there is a fun activity/coloring book that can be found here. Some faults reach the surface and can be found by geologists. (Andy Bronson / The Herald). In the 1990s, scientists producedan animationthat shows inundation, and people wont have much time to run to higher ground. Jump from 60 to 600 per week in just 5 years in Pahala, Is the Cascadia Subduction Zone about to blow? Although we know much about active faults and earthquakes, there is much more to learn. Someone screams. Most are too small to be felt or cause damage. 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. 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. Earthquakes. 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. Lidar maps show the Earths surface without vegetation. Often this cracking happens because a soft part of the ground liquefies during the shaking. 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. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. We pray for people of WA and our all north Americans as well. The trench did expose faults, but it was not possible to conclusively demonstrate offset of Holocene units. Geologists are constantly trying to better understand the faults in our state. Its just the way scientists work, he said. Tohoku killed nearly 16,000 people; most died as a result of drowning or being crushed in the tsunami. Tsunamis triggered by earthquakes usually require at least a M7 event. endobj These quakes are capable of magnitudes from 7 to over 9. 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 Safe America Foundation suggests texting as a way of communication. But Forson says you also need to know what to do when the shaking happens. Electricity, water, natural gas, and phones may not work. These sediments were laid down 20,000 to 60,000 years ago, before the last ice age. When a fault with vertical movement ruptures the ocean floor, it lifts up part of the ocean. Dishes jitter off tables, shattering on the floor. A 2014 map shows what we know about the age of faults in Washington. They didnt recognize the significance of what they found. 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. It startled Johnson that such massive faults had gone undetected for so long. Secure .gov websites use HTTPS Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. This diagram shows the many types of active faults and the general location of past earthquakes in Washington. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. Evacuate to higher ground if you are near a large body of water. Tap/click on "gear icon" for options and settings. 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. A lot of people are transplants, Forson said. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. The friend obliged. The trenches exposed glacial deposits disrupted by faults and liquefaction features. Proceed cautiously once the earthquake has stopped. Here, were looking at one of the bigger faults in the region, he said. On a brilliant November day, Sherrod took in the panorama from the parks bluff. During site visits in 2005, Sherrods team found evidence of four SWIF earthquakes in the past 30,000 years. @\;L;=}%FC*l $@ 4x: 888O~xrsxx'/*rGRF\gI%~x(G-^-hjjq kx/V ou0hyegy0;ei`Tx&ilZ )TmZ$vb,`bQm|DR5x/ These large underwater slides only occur during very large earthquakes and are one way to learn about earthquakes that happened thousands of years ago. Some of these faults are in remote areas. Both of these things can cause equal or greater damage than the actual earthquake. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. This was a problem because no two locations would agree on the size of the same earthquake. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. The strength of ground shaking (called strong motion by seismologists) usually decreases with distance from the earthquake source. The best thing you can do is to become prepared. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. 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. PI22343). Washington has few large normal faults because it is mostly in a region of compression. An official website of the United States government. Areas like these are also susceptible to liquefaction. Over time, fault movement has created some interesting geologic features. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. (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. 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 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. Once the shaking has stopped, exit the building if it is safe to do so. On a frigid, blustery day in December 2018, Sherrod revisited the site where he conducted much of his field work. Washington has the second highest risk in the U.S. of these large and damaging earthquakes because of its geologic setting. . This fault zone was originally named the Devils 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. Prepare to be on your own for at least three days. Photo from, Liquefaction can be a big problem. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. 3 0 obj The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. South Whidbey Island Fault Zone. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. <>>> The Mercalli Intensity scale is another historical way to measure the intensity of an earthquake. What about the localized tsunami risk? Each type has different kinds of earthquakes. 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. Also issued a warning for the UK that the Italian chaos could come to Britain Scientists are not sure how far east it goes. Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. On an inactive fault, the sea would have risen at the same rate at both locations. Avoid stopping near or under buildings, trees, overpasses, or utility wires. Landslide at Salmon Beach was triggered by the 1949 Tacoma earthquake and caused a tsunami. Hey Biden! An abrupt rise or decline in sea level would reveal if the fault had triggered a quake before. The fault's length depends on whom you ask, Sherrod said. The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. There are also tsunami evacuation signs on the highways. Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. 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). Sensitive seismographs located throughout the state, and all over the world, measure this seismic energy. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. For example, a building on soft soil will experience more shaking than the same building on bedrock. Stay inside until the shaking stops and it is safe to go outside. View of the Sunset Lake liquefaction failure about three weeks after the earthquake. 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. These cookies do not store any personal information. Notice the Seattle Fault Zone bounding the Seattle Basin to the south. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. PO Box 5000 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. Geologic maps show the types and ages of rocks and younger deposits that are found at or near the Earth's surface. Map by And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. The Seattle fault last ruptured about 1,100 years ago in AD 900950. If the epicenter is Everett, the SWIF could cause. The years have gone by. Also check out Ear to the Ground, published by the Department of Natural Resources. This is similar to how sound is quieter when you move away from a speaker. The South Whidbey Island Fault is also dangerous. Because after a region-wide event, it could take that long for help to come from the rest of the country and world. By Julia-Grace Sanders The Everett Herald May 14, 2021 2:40 pm, Luella Meaux: November 21, 1929 January 21, 2023, Claudia Anderson: October 1, 1939 January 31, 2023, Chieko Yamane Miller: July 26, 1936 February 16, 2023, Guarding the flock: Chicken farms rely on specialized dogs, Flying colors: Irish artist finds success on Whidbey. Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other.

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