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Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. Stay inside until the shaking stops and it is safe to go outside. Much of the land along the southwestern part of the lake cracked and subsided. 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. In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. Faults often occur at and near the boundary of large tectonic plates because the plates are moving in different directions. The average time between large earthquakes is about 535 years, but has been as little as 200 years, and more than 1,000 years. The plate that is forced down can have faults within it that still rupture and produce earthquakes. Earthquakes occur nearly every day in Washington. 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. 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. These large underwater slides only occur during very large earthquakes and are one way to learn about earthquakes that happened thousands of years ago. 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). The years have gone by. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. In places where there is little vegetation, different rock types and faults can be found with relative ease. (Andy Bronson / The Herald). 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. 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. A 2014 map shows what we know about the age of faults in Washington. Other types of seismic energy (S waves) also travel through the earth, but they move with a side-to-side (shearing) motion. There are many other active faults in Washington and any of these could produce a large earthquake in the future. Tsunami waves can travel over 500 miles per hour in the open ocean. In Washington, we do not have tsunami walls. 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. A .gov website belongs to an official government organization in the United States. Necessary cookies are absolutely essential for the website to function properly. A baristas hand hovers over the bean grinder. USA Earthquake Hazard Map. Sherrod and others, 2008 #7652) report results from four trenches located near Crystal Lake: Flying Squirrel trench (572-5), Mountain Beaver trench (572-6), Beef Barley trench (572-7), and French Onion trench (572-8). The southern Whidbey Island fault should be considered capable of generating large earthquakes (Ms ?? And experts fear it could be even worse than The Big One.. Both of these things can cause equal or greater damage than the actual earthquake. Evacuate to higher ground if you are near a large body of water. In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. By clicking Accept, you consent to the use of ALL the cookies. The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. On a frigid, blustery day in December 2018, Sherrod revisited the site where he conducted much of his field work. 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 fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. The process of breaking and moving rock releases a large amount of energy that travels through the Earth as seismic waves. Clicking on the map will download the publication. Customers lift their eyes from phone screens. from Whidbey Island to Vancouver Island (Figure 1). Brick chimneys cascade off rooftops. Identify and secure items in your home or work that could cause damage. HomePrograms and ServicesGeologyGeologic Hazards. The southern Whidbey fault is shallow, running right under Snohomish County as opposed to many miles off shore like the Cascadia fault. If you are already planning your Christmas gifts, please buy with us on Amazon. District Court: (800) 946-9765, South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario. But opting out of some of these cookies may affect your browsing experience. Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. 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 fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. 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. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. In the early 2000s, USGS scientists including Brian Sherrod set out to further Johnsons work and better understand the slumbering fissure. Theyre FREE CLICK HERE to subscribe, EAR TO THE GROUND WITH DNR & COMMISSIONER FRANZ, Tree Link helps you answer questions about urbantrees. In some areas getting up a hill to higher ground will be difficult. Aftershocks can be nearly as large as the main earthquake and can cause significant additional damage. It is not yet possible to predict when a fault will have an earthquake. 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 Before modern record keeping, Native Americans lived in the Pacific Northwest for thousands of years. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> They didnt grow up here, they havent heard this story. 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. Landslides can be caused by strong ground shaking during an earthquake. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. Over time, fault movement has created some interesting geologic features. 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. View Earthquake Map Faults Interactive fault map and comprehensive geologically based information on known or suspected active faults and folds in the United States. Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. Sometimes there may be a layer of volcanic ash or charcoal that has been deformed by the fault. At a downtown coffee shop, the mugs begin to chatter. STAY THERE until the shaking stops. For the most up-to-date information, please refer to the interactive fault map. An official website of the United States government. % Finding and learning about faults requires many different aspects of geology and geophysics. 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. stream Secure .gov websites use HTTPS The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. 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. 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. Do you know what to do if there is an earthquake? Expect aftershocks. This earthquake caused parts of Restoration Point near on Bainbridge Island to be lifted 35 feet straight up. The trenches exposed glacial deposits disrupted by faults and liquefaction features. Save my name, email, and website in this browser for the next time I comment. Most faults are considered active if they have evidence for movement (this includes earthquakes) within the past 12,000 years (the Holocene time period). It is capable of generating severe earthquakes that would impact the entire west coast. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. The strength of ground shaking (called strong motion by seismologists) usually decreases with distance from the earthquake source. There are also many faults that have not been studied enough to know if they are active. Earthquakes cause damage by moving and shaking the ground, sometimes for several minutes. Cover your head and neck with your arms to protect against falling debris. Fault Activity Map of California. A seiche is a large standing wave caused by the resonance of a particular period of wave energy. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. The bluff, where the cabins now sit, could have jutted up in the most recent Whidbey fault quake, Sherrod said. America is going to be punished just like the rest of the world. 3 0 obj Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System). Drop to your hands and knees. There are also tsunami evacuation signs on the highways. The fault, not so much. They knew something was there, said Sam Johnson, a retired USGS geologist who would follow up on their work. Although both seiches and tsunamis can be large and destructive, they are created differently. It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. of Earth and Space Sciences, Box 351310, Univ. An official website of the United States government. Devastating wind storms. On an inactive fault, the sea would have risen at the same rate at both locations. The South Whidbey Island Fault is also dangerous. The Cascadia subduction zone just off the Washington coast is this kind of fault and is one of the largest geologic hazards to our state. Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. Sheriff:(360) 679-7310, Juror Recordings Hundreds could die, with thousands more injured. Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface. The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). This diagram shows the many types of active faults and the general location of past earthquakes in Washington. After the shaking stopped the sand regained its strength. The buildings sank when ground shaking weakened the underlying sediments. 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. A half dozen people reaching for the last can of soup, someone could lose their life over that. Tsunamis triggered by earthquakes usually require at least a M7 event. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. The shaking usually lasts less than a minute and doesnt generally cause a tsunami or have many aftershocks. PO Box 5000 An abrupt rise or decline in sea level would reveal if the fault had triggered a quake before. Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. Like other faults, when enough stress builds up, the megathrust will rupture. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. Not all faults are active. The seismic mapping had cost millions of dollars far beyond what most geologists on a government budget could scrape together. The boundary between the two plates covers a large area and can lock together. You have entered an incorrect email address! Most injuries occur when people inside change rooms or try to leave the building. Do not exit a building during the shaking. Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. The southern Whidbey fault is unlike more visible faults on the West Coast. 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. Secure .gov websites use HTTPS A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. Experts believe a magnitude 9.0 could happen there anytime in the next 200 years or so. The southern Whidbey Island fault divides the two. Consider whether earthquake insurance is right for you. Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. 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 It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. The South Whidbey Island Fault and Darrington Devil's Mountain Fault bound the Everett Basin. Johnson et al. Geologists at the Survey spend time mapping the geology of the state, looking for faults, folds, landslides, and different rock types. Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. Why is Strange Sounds focusing so much on disaster preps? 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. Drop, Cover, and Hold On whenever you feel shaking. This can cause landslides to occur where they wouldnt normally happen. The tsunamis can travel far inland and deposit layers of sand and organic material. 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 Geologic Information Portal has a Natural Hazards theme that shows active faults and earthquakes. You also have the option to opt-out of these cookies. The fault's length depends on whom you ask, Sherrod said. Because they can travel great distances, tsunamis generated from earthquakes across the ocean can still cause damage. The map also shows potentially active faults from a separate 2014 report (click here to download). These aftershocks can last for hours to weeks or months. . A drill rig left of the blockade is collecting data about the failure. These older faults do not have any evidence for recent activity, but the Earth is always changing. Image from the Pacific Geoscience Center of the Natural Resources of Canada. These faults and earthquakes occur in the continental crust of North America. Everything points to one thing, Sherrod said, waving his hand across the inland sea. Some types of seismic energy (P waves) are similar to sound energy that is released if you break a twig or slide a chair across the floor. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. Another big one is expected, and it could be devastating. , * NOTE: Hazard maps for each jurisdiction will only be included if that jurisdiction is at risk to that hazard., Copyright Island County. 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. Sherrod says practically every place they. The faults length depends on whom you ask, Sherrod said. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. southern Whidbey Island fault zone (Class A) No. Know what to expect. Swarm of hundreds of small earthquakes rattle Vancouver Island. Electricity, water, natural gas, and phones may not work. 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. So the fault remained mostly a mystery until the 1990s. It will happen; we dont know when.. A national credit rating service has improved its opinion of WhidbeyHealths financial future. 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. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). The northwest-trending southern Whidbey Island fault zone occurs along a significant terrane boundary between basement blocks underlain by Eocene marine basalts of the Coast Range province to the southwest and pre-Tertiary metamorphic rocks of the Cascades province to the northeast. The age of the earthquake is learned by dating the organic material in these tsunami deposits. Map by And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. 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. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. Do you live or work near an area that could have liquefaction? Seismic waves travel at hundreds to thousands of miles per hour and quickly reach the surface where they are felt or measured. This fault will have an earthquake in the future, but we cannot predict exactly when.