This category only includes cookies that ensures basic functionalities and security features of the website. 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 few miles southeast across the white-capped waves of Admiralty Bay, Lake Hancock rises and falls with the tides. Geologists do not yet know how often earthquakes happen on this fault. An increase of 2 means that ~1,000 times more energy is released. The ground shaking from these earthquakes can last for several minutes. Shallow faults produce earthquakes in the upper 18 miles (30 kilometers) of the Earths crust. The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). This is sometimes called "The Big One" by news media. The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. If a large earthquake happens, be prepared for many more earthquakes. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. 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 when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. This might include flammable appliances like a water heater, tall items like book cases, or heavy pictures. Photo courtesy of National Center for Tsunami Research, NOAA. Do you know what to do if there is an earthquake? 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. A lock () or https:// means youve safely connected to the .gov website. % 3 0 obj Share sensitive information only on official, secure websites. southern Whidbey Island fault zone (Class A) No. Because after a region-wide event, it could take that long for help to come from the rest of the country and world. This is similar to how sound is quieter when you move away from a speaker. Many faults have not been studied enough to know if they are active. The friend obliged. The study of seismic waves is called seismology and has allowed scientists to learn much about the internal structure of the Earth. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. California Department of Conservation. Close to shore, this same wave could reach heights of 30100 feet or more. The marshy deposits are about a meter higher at Lake Hancock. Sometimes there may be a layer of volcanic ash or charcoal that has been deformed by the fault. 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. Here, were looking at one of the bigger faults in the region, he said. 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. The fault, not so much. Image from the Pacific Geoscience Center of the Natural Resources of Canada. The Seattle Fault is also likely to create a tsunami that would inundate Harbor Island and much of SODO, Interbay, and the waterfront. 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. Geologists are constantly trying to better understand the faults in our state. The trenches exposed glacial deposits disrupted by faults and liquefaction features. 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. Finding and mapping these faults is an important mission of the Washington Geological Survey. The height difference likely was caused by a 7.5 magnitude earthquake on the fault about 2,700 years ago, Sherrod said. This means that when the Seattle fault ruptures the south side of the fault moves up relative to the north side. Every year Western. Fault Activity Map of California. And experts fear it could be even worse than The Big One.. 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. Knowing how often large earthquakes have happened in the past helps us to know how often they might occur in the future. These types of faults are common, but usually small. Washington, Seattle, WA 98195 2 U.S. Geological Survey, 345 Middlefield Road, M/S . America is going to be punished just like the rest of the world. Camano Island, WA 98282, Mailing Address The 2011 Tohoku earthquake in Japan occurred on this type of fault and released enough energy to slightly change the Earths axis of rotation. The Flying Squirrel and Mountain Beaver trenches cross the Cottage Lake lineament. These and other problems led to the search for a scale that was based on the physical processes that happen during an earthquake. Because Japan was so well prepared, mostretrofitted buildingsoutside of the tsunami zone survived. By sampling sediment from the marsh to the beach berm, Sherrod and his research partner, Harvey Kelsey, developed a timeline of the oceans climb. You just need one person to crash or a power line to fall over the road, and the roads are unusable.. That could spell trouble not only for its namesake island but for south and north King County and further west. Since their initial discovery, research has shown that the actual number of earthquakes is somewhere between 5 and 10 for each change in magnitude. 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. Radiocarbon dating and other paleoseismic methods have also confirmed this date. 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. Stratigraphy in the Flying Squirrel trench showed gentle warping of late glacial and post-glacial sediments; no faults were exposed. They didnt grow up here, they havent heard this story. 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. For example, a M7 earthquake releases 32 times more energy than a M6 earthquake, and 1,000 times more than a M5 earthquake. A lock () or https:// means youve safely connected to the .gov website. By finding the age of the deformed layer, a paleoseismologist can determine the minimum age of the fault. The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. The coast is now the home of one of the states largest network of warning sirens called All Hazard Alert Broadcast (AHABs). Dishes jitter off tables, shattering on the floor. Unlike sound, ground shaking can be amplified or attenuated (made less) depending on the type of material at the Earths surface. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. Earthquakes on shallow faults typically last 20 to 60 seconds and the shaking is localized to the general area of the fault. In Seattle, the quake damaged buildings, weakened bridges, started fires and opened cracks in the earth. Clicking on the map will download the publication. Even if the earthquake is too small to be felt by people, seismographs can detect it. Geologic maps show the types and ages of rocks and younger deposits that are found at or near the Earth's surface. Liquefaction is when wet soil or sediment loses strength because it is being shaken during an earthquake. PI22343). Learn about at-risk areas and become prepared. 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 . Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. Tsunamis triggered by earthquakes usually require at least a M7 event. 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). Superior Court:(800) 254-2755 Bookcases and china cabinets topple, trapping people beneath. 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. 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. Some residents may lose housing temporarily or permanently. The Mercalli Intensity scale is another historical way to measure the intensity of an earthquake. 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. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. If you are already planning your Christmas gifts, please buy with us on Amazon. But scientists theorize that the area has suffered only four . These quakes are capable of magnitudes from 7 to over 9. Necessary cookies are absolutely essential for the website to function properly. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. 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). 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 evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. The map is from a 2007 report (click here to download) on seismic design categories in Washington. Using the stratigraphic column from the Freeport quadrangle map, confirm that you can recognize . Drop, Cover, and Hold On whenever you feel shaking. Secure .gov websites use HTTPS It could also create dangerous currents and hazards to the north including Everett. These cookies will be stored in your browser only with your consent. 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. 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. Like a sonogram, the seismic surveys allowed Johnson to see outlines of massive fissures in the earths crust. Scientists dont know. 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. The tsunami becomes taller as the ocean becomes shallow. . Oil companies descended in search of riches. Geologists and geophysicists at the Washington Geological Survey map out these areas of amplification to help reduce damage during an earthquake. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington. Power could be out for days. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. California Geological Survey. It is not yet possible to predict when a fault will have an earthquake. 121 N East Camano Dr 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). What about the localized tsunami risk? 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. 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. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. 1 School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia V8P 5C2, Canada 2 Department of Earth and Environment, Boston University, Boston, Massachusetts 02215, USA The seismic mapping had cost millions of dollars far beyond what most geologists on a government budget could scrape together. 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. The term active can have different meanings. These faults and earthquakes occur in the continental crust of North America. The southern Whidbey fault is shallow, running right under Snohomish County as opposed to many miles off shore like the Cascadia fault. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. 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. We pray for people of WA and our all north Americans as well. The map is from a, This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. Secure .gov websites use HTTPS 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. When this happens, even a very small slope can cause the ground to slide. 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. But the mapping offered geological clues that the newly found fault was indeed capable of future quakes. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. The Eastern Sierra fault along the east side of the Sierra Nevada mountains in California is a good example of an active normal fault. The southern Whidbey Island fault divides the two. A .gov website belongs to an official government organization in the United States. Faults can also be grouped based on what part of the crust they occur in. Sherrods son has since completed graduate school in applied geosciences. Part 2 will be full Martial Law and mandatory vaccines? Avoid stopping near or under buildings, trees, overpasses, or utility wires. The 1964 M9.2 Alaska earthquake created a large tsunami from the fault rupture, and many smaller tsunamis from on-land and underwater landslides. Large earthquakes are likely to happen in Washington during your lifetime. Beef Barley and French Onion trenches cross the Little Bear Creek lineament. The most recent hit roughly 2,700 years ago. For example, the Cascadia subduction zone has had between 15 to 19 earthquakes over the past 10,000 years. The medic said colleagues were becoming sick and emotionally overwhelmed Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. endobj If the epicenter is Everett, the SWIF could cause. Seismic waves travel at hundreds to thousands of miles per hour and quickly reach the surface where they are felt or measured. For example, it is unlikely that you will be able to use electricity, cell phones, or the internet. The moment magnitude scale replaced the Richter scale in the late 1970s. 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. Below you will find links to view and download hazard maps created for each jurisdiction included in the current mitigation planning process. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. Most damage and loss of life in earthquakes is a result of ground shaking. Scientists are not sure how far east it goes. An earthquake can be a scary event. Most injuries occur when people inside change rooms or try to leave the building. 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. But they didnt document it hardly at all.. The last major earthquake was over 300 years ago. The French Onion trench exposed glaciolacustrine claystones, till, colluvial deposits, and Holocene soils. Not all faults are active. This website uses cookies to improve your experience while you navigate through the website. Contact Us, Whidbey Office Over time, fault movement has created some interesting geologic features. We do not encourage people to evacuate in vehicles. Tsunami waves can travel over 500 miles per hour in the open ocean. That place is the Ocosta School. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. In addition, the Survey performs seismic safety evaluations of schools. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. In the early 2000s, USGS scientists including Brian Sherrod set out to further Johnsons work and better understand the slumbering fissure. 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

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