This fault produces some of the largest and most damaging earthquakes in the world (M9). There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. Each type has different kinds of earthquakes. A normal fault occurs when two blocks are pulled away from each other. Lidar maps show the Earths surface without vegetation. The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). When earthquakes occur on faults that reach the Earths surface, the ground may rupture. However, we can learn which faults are active and which are inactive. 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. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. The friend obliged. Once we got it, we were sort of shocked to see these big faults in the Puget lowlands, he said. This is similar to how sound is quieter when you move away from a speaker. Once the shaking has stopped, exit the building if it is safe to do so. Small talk stops. He said he believes dramatic shifts from that quake also may be visible on the western edge of Camano Island. Faults can also occur within a tectonic plate when the plate itself is deforming. The tsunamis can travel far inland and deposit layers of sand and organic material. The Seattle fault last ruptured about 1,100 years ago in AD 900950. One model suggests it extends to about 30 miles east of Yakima. One of the best views of SWIF should be from Grand Avenue Park in Everett. 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. Along the coast residents may have between 20 and 30 minutes to get to higher ground. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington. One model suggests it extends to about 30 miles east of Yakima. 1 NE 7th Street The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. He combed through state and federal data to understand the risks, and to help train first responders. <> The next earthquake is inevitable, but the variability makes it difficult to know exactly when. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. Source: United States Geological Survey. Below you will find links to view and download hazard maps created for each jurisdiction included in the current mitigation planning process. A national credit rating service has improved its opinion of WhidbeyHealths financial future. These types of faults are common, but usually small. You also have the option to opt-out of these cookies. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. 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 . 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. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. The shaking can damage or destroy buildings and other infrastructure. 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. The southern Whidbey Island fault (SWIF) stretches from the vicinity of Victoria, B.C., across Puget Sound as far as the Cascade Range. The Moment Magnitude Scale (M) measures the total amount of seismic energy (known as moment to engineers and seismologists) released by an earthquake. Snohomish, King and Island counties would be expected to see the. For example, it is unlikely that you will be able to use electricity, cell phones, or the internet. This was a problem because no two locations would agree on the size of the same earthquake. Though it was not directly related to Johnsons work, he asked a friend working for Mobil Oil to pass along the information. % The April 1949 Tacoma earthquake measured 7.1 on the Richter Scale and caused damage from southern Oregon to British Columbia. 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. What we know about this fault is that its ruptured may times in the pastit will happen again. Because after a region-wide event, it could take that long for help to come from the rest of the country and world. Official websites use .gov 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. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. This new method allows geologists to see through trees and vegetation to find new faults. The most recent hit roughly 2,700 years ago. The last major earthquake was over 300 years ago. Faults can also be grouped based on what part of the crust they occur in. The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. Landslides can be caused by strong ground shaking during an earthquake. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). 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 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). 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. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. The Survey conducts and publishes geologic mapping to identify and characterize faults throughout the state. They knew something was there, said Sam Johnson, a retired USGS geologist who would follow up on their work. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. What about the localized tsunami risk? 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. Superior Court:(800) 254-2755 The best thing you can do is to become prepared. 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 most important thing you can do before the next earthquake is to prepare. In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. It could also create dangerous currents and hazards to the north including Everett. The southern Whidbey fault is unlike more visible faults on the West Coast. Another big one is expected, and it could be devastating. For the most up-to-date information, please refer to the interactive fault map. Sherrod shrugged his shoulders. Unlike The Big One, scientists who have studied the southern Whidbey fault have far less understanding of when the next sudden shift might hit. We also use third-party cookies that help us analyze and understand how you use this website. The mission of the Washington Geological Survey is to collect, develop, use, distribute, and preserve geologic information to promote the safety, health, and welfare of the citizens, protect the environment, and support the economy of Washington. Scientists have been trying to understand how often earthquakes happen for over 100 years. Both studies suggested that the SWIF 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. Proceed cautiously once the earthquake has stopped. Moving inland, the Seattle Fault is capable of a magnitude 7. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. The years have gone by. Faults can be grouped based on their relative movement into three types. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. For example, in the open ocean a tsunami may be less than a few feet tall. In some areas getting up a hill to higher ground will be difficult. Kelsey and others (2004 #7651) compared sea-level histories at two salt marshes that straddle a northeast strand of the southern Whidbey Island fault zone: Crockett Marsh (site 572-1) located north of the northeastern fault strand is 8 km north of Hancock Marsh (site 572-2), south of the fault strand. A lock () or https:// means youve safely connected to the .gov website. You just need one person to crash or a power line to fall over the road, and the roads are unusable.. In the late 1960s, speculators considered the Puget Sound region a frontier for petroleum exploration. The Cascadia subduction zone along the Washington and Oregon coast is one of the biggest hazards to our state and is a good examples of this kind of fault. 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 diagram shows the many types of active faults and the general location of past earthquakes in Washington. Scientists dont know. The buildings sank when ground shaking weakened the underlying sediments. These faults and earthquakes occur in the continental crust of North America. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. Washington has few large normal faults because it is mostly in a region of compression. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. 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. Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. 121 N East Camano Dr And experts fear it could be even worse than The Big One.. California Geological Survey. Higher risk areas are in orange and lower risk areas are in green. When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. 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. Close to shore, this same wave could reach heights of 30100 feet or more. 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 age of the earthquake is learned by dating the organic material in these tsunami deposits. It will happen; we dont know when.. 2 0 obj 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. 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. The plate that is forced down can have faults within it that still rupture and produce earthquakes. Sensitive seismographs located throughout the state, and all over the world, measure this seismic energy. A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . southern Whidbey Island fault zone (Class A) No. 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 area of North Bend, the fault zone is 4 miles wide and consists of a series of parallel faults. 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. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. At a downtown coffee shop, the mugs begin to chatter. " A lot of people are transplants, " Forson said. Reverse faults are usually steep and occur in regions of compression. Photo from https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg. One of these cracks appeared along the pathway around Green Lake. Many faults have not been studied enough to know if they are active. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. 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. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. HOLOCENE FAULT SCARPS AND SHALLOW MAGNETIC ANOMALIES ALONG THE SOUTHERN WHIDBEY ISLAND FAULT ZONE NEAR WOODINVILLE, WASHINGTON By Brian L. Sherrod1, Richard J. Blakely2, Craig Weaver1, Harvey Kelsey3, Elizabeth Barnett1, and Ray Wells4 1 U.S. Geological Survey, Dept. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. Other faults are inactive and are left over from much older periods of deformation. The buildings sank when ground shaking weakened the underlying sediments. The Cascadia subduction zone last ruptured over 300 years ago on January 26, 1700. 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). Even if the earthquake is too small to be felt by people, seismographs can detect it. This uplift creates a very broad wave called a tsunami. It usually also means that there are earthquakes (even small ones) on the fault. A half dozen people reaching for the last can of soup, someone could lose their life over that. Johnson and others . Hundreds could die, with thousands more injured. The bluff, where the cabins now sit, could have jutted up in the most recent Whidbey fault quake, Sherrod said. Even when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. 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. Despite its location well offshore, a Cascadia quake would likely kill at least 10,000 and injure more than 30,000 in Washington, Murphy found. A seiche is a large standing wave caused by the resonance of a particular period of wave energy. This map shows different seismic design categories that correlate with amount of seismic risk. These quakes are capable of magnitudes from 7 to over 9. Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. stream An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. This kind of grouping gives us information about how common earthquakes might be and how large an area may be affected. A small quake was registered in the Coupeville area just this summer. It startled Johnson that such massive faults had gone undetected for so long. Devastating wind storms. The South Whidbey Island Fault and Darrington Devil's Mountain Fault bound the Everett Basin. This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. Washington has dozens of active faults and fault zones. 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. 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. When an earthquake happens there will not be time to google what you are supposed to do. Stop as quickly as safety permits and stay in the vehicle. 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. Geologists do not yet know how often earthquakes happen on this fault. In places where there is little vegetation, different rock types and faults can be found with relative ease. PO Box 5000 Contact Us, Whidbey Office Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. Image from the Pacific Geoscience Center of the Natural Resources of Canada. One of the most important new technologies for finding faults (and landslides too) is called lidar. Move away from buildings, streetlights, and utility wires if you can. Once in the open, Drop, Cover, and Hold On. The map is from a, This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. Maps. Roads, bridges, or ramps may have been damaged by the earthquake. Part 2 will be full Martial Law and mandatory vaccines? Before modern record keeping, Native Americans lived in the Pacific Northwest for thousands of years. The evidence shows each lake rests on different free-floating jigsaw pieces of planetary crust, separated by the southern Whidbey Island fault. Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. District Court: (800) 946-9765, South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. It can also make landslides that are much bigger than expected. Beef Barley and French Onion trenches cross the Little Bear Creek lineament. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. Buildings could sustain extensive damage. Earthquakes on faults like these may cause tsunamis in the Puget Sound region. Expect aftershocks. Camano Island, WA 98282, Mailing Address . Earthquakes occur nearly every day in Washington. 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 SWIF has been assessed by the USGS as capable of generating the largest crustal earthquake in Puget Sound. An abrupt rise or decline in sea level would reveal if the fault had triggered a quake before. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. Graphic from IRIS. Much of the land along the southwestern part of the lake cracked and subsided. Learn about at-risk areas and become prepared. Dishes jitter off tables, shattering on the floor. The Straight Creek fault in the Cascade Range is an example of this kind of fault and has ~5060 miles of movement across it. Most injuries occur when people inside change rooms or try to leave the building. Photo from Pacific Northwest Seismic Network Seismo Blog. Faults often occur at and near the boundary of large tectonic plates because the plates are moving in different directions. 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). 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. 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. Unlike sound, ground shaking can be amplified or attenuated (made less) depending on the type of material at the Earths surface. M 7.4 Scenario Earthquake - Southern Whidbey Island fault-southern Overview Interactive Map Regional Information Impact ShakeMap Technical Origin Download Event KML Earthquakes Hazards Data & Products Learn Monitoring Research M 7.4 Scenario Earthquake - Southern Whidbey Island fault-southern 2017-05-12 20:14:09 (UTC) 48.036N 122.452W A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. They didnt grow up here, they havent heard this story. Washington, Seattle, WA 98195 2 U.S. Geological Survey, 345 Middlefield Road, M/S . As an example, parts of Seattle and certain areas of downtown Olympia are built on softer ground that will amplify ground shaking during an earthquake. This earthquake caused parts of Restoration Point near on Bainbridge Island to be lifted 35 feet straight up. While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. He said scientists have known about the southern Whidbey fault for decades. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. Avoid stopping near or under buildings, trees, overpasses, or utility wires. His team wanted to find the rate of sea level rise along the shore. For several years, scientists pondered where this important regional fault zone continues southwestward from its mapped location in the Everett area. Its a natural curiosity.. The experts say few are ready. America is going to pay for sitting back doing nothing while almost 70 million babies were slaughtered and their body parts sold to the highest bidder for the last 43 years. 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. Geoscientist Brian Sherrod stands near the submerged southern Whidbey Island fault line at the Brightwater Treatment Plant in Woodinville. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. In fact, new faults are found every year during our geologic mapping efforts. This is called liquefaction and is discussed in the next section. Consider whether earthquake insurance is right for you. After the shaking stopped the sand regained its strength. The last time was 1,000 years ago between 900 and 903 A.D., said Forson. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. Seconds later, its as if Whidbey Island is trapped in a cocktail shaker, lurching back and forth. That could spell trouble not only for its namesake island but for south and north King County and further west. California Department of Conservation. By clicking Accept, you consent to the use of ALL the cookies. If they know theres data available that could help them in any way, they want to get it.