Earthquakes occur nearly every day in Washington. During site visits in 2005, Sherrods team found evidence of four SWIF earthquakes in the past 30,000 years. 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. 2 0 obj Ready to retrofit? Once the shaking has stopped, exit the building if it is safe to do so. southern Whidbey Island fault zone (Class A) No. A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. A normal fault occurs when two blocks are pulled away from each other. Cover your head and neck with your arms to protect against falling debris. Know what other hazards you might face. They knew something was there, said Sam Johnson, a retired USGS geologist who would follow up on their work. Scientists are not sure how far east it goes. They conclude the observed features have a glaciotectonic origin and are not seimotectonic. Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. It is mandatory to procure user consent prior to running these cookies on your website. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> Faults can be grouped based on their relative movement into three types. This is a very good example of a strike-slip fault. 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. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington. They didnt recognize the significance of what they found. Then the world rattles up and down. These sediments were laid down 20,000 to 60,000 years ago, before the last ice age. For example, in the open ocean a tsunami may be less than a few feet tall. 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. The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. 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 So the fault remained mostly a mystery until the 1990s. When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. This website uses cookies to improve your experience while you navigate through the website. Superior Court:(800) 254-2755 One or possibly two of the unconformities are interpreted as event horizons. The plate that is forced down can have faults within it that still rupture and produce earthquakes. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. Power could be out for days. One model suggests it extends to about 30 miles east of Yakima. Floods. Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. The marshy deposits are about a meter higher at Lake Hancock. The material becomes so weak that it behaves more like a liquid than a solid. Large earthquakes are likely to happen in Washington during your lifetime. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. Johnson et al. Liquefaction can be a big problem. The San Andreas fault in California is a good example of a very active strike-slip fault. Earthquakes can trigger landslides and tsunamis which can happen after the main event. Hey Biden! Geologic maps show the types and ages of rocks and younger deposits that are found at or near the Earth's surface. Quake fault under Whidbey linked to potential mainland dangers Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. The southern Whidbey Island fault divides the two. 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. Aftershocks can be nearly as large as the main earthquake and can cause significant additional damage. Story telling is an important part of the Native tradition and is how their history is passed down to the next generation. Some people in places like SODO and Harbor Island may have to flee to higher floors in a building. 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. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. Most are too small to be felt or cause damage. After the shaking stopped the sand regained its strength. 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. The continued movement along faults over millions of years can build mountains, tear a continent apart, and move tectonic plates thousands of miles. An increase of 2 means that ~1,000 times more energy is released. 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. Close to shore, this same wave could reach heights of 30100 feet or more. %PDF-1.5 In general, larger faults make larger earthquakes. The map is from a 2007 report (click here to download) on seismic design categories in Washington. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. Earthquake Fault Maps in Seattle and Washington State During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. Drop to your hands and knees. Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. Once in the open, Drop, Cover, and Hold On. Much of the Southern Whidbey Island fault zone (SWIF), which runs in a north-westward direction from Woodinville to near Port Townsend, Washington, remains mostly . 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. Quaternary Fault and Fold Database of the United States - USGS The strength of ground shaking (called strong motion by seismologists) usually decreases with distance from the earthquake source. The map also shows potentially active faults from a separate 2014 report (click here to download). Drop, Cover, and Hold On whenever you feel shaking. Radiocarbon dating and other paleoseismic methods have also confirmed this date. 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. Faults can also occur within a tectonic plate when the plate itself is deforming. After the shaking stopped the sand regained its strength. Washington State Earthquake Hazard Map. 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. What we know about this fault is that its ruptured may times in the pastit will happen again. So they dont necessarily know the threats they face.. (360) 678-5111 It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. Never use a lighter or match near damaged areas. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. Photo by Steve Palmer. Most injuries occur when people inside change rooms or try to leave the building. Hold on to any sturdy shelter until the shaking stops. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. 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. /L\Axc4Q/w4Ks^#, sRITgZf>,e}iI5,F_ADGc?f e@L. 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. This is called liquefaction and is discussed in the next section. And what were looking at is water.. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. Seattle Fault - Wikipedia This uplift creates a very broad wave called a tsunami. (Andy Bronson / The Herald). 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 seismic mapping had cost millions of dollars far beyond what most geologists on a government budget could scrape together. Restoring tap water to some homes could take over a year. 1 0 obj 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. 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. Sometimes there may be a layer of volcanic ash or charcoal that has been deformed by the fault. 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. This fault produces some of the largest and most damaging earthquakes in the world (M9). Experts have warned that UK outbreak may be around two weeks behind Italys. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. South Whidbey Island Fault Zone. A national credit rating service has improved its opinion of WhidbeyHealths financial future. This means that the internet, your cell phone, grocery stores, and gas stations may also not work. This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. In 1985, with little concrete evidence of its existence, the pair included the possible fault on a geologic map published by the USGS. Earthquakes occur nearly every day in Washington. When an earthquake happens there will not be time to google what you are supposed to do. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. This map shows areas of seismic risk from high (red) to low (grayish-green). Finding faults and knowing how often they rupture is one of the most important tasks to keep society safe from these hazards. Tohoku killed nearly 16,000 people; most died as a result of drowning or being crushed in the tsunami. The years have gone by. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Photo from Pacific Northwest Seismic Network Seismo Blog. Earthquakes and Faults | WA - DNR - Washington State Department of It is capable of generating severe earthquakes that would impact the entire west coast. The next earthquake is inevitable, but the variability makes it difficult to know exactly when. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. . 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. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. PDF Cretaceous-Jurassic accreted terrains - University of Washington Prepare to be on your own for at least three days. 3. Aftermath: Infrastructure won't fare well in a big quake <>>> Some residents may lose housing temporarily or permanently. Be prepared and read more on DNR, USGS, King5, Strange Sounds and Steve Quayle. 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). The Seattle fault is a good example of a fault that is mostly reverse. Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. 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. 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). We do know that it is active and will likely produce a large M67.5 earthquake when it next ruptures. Shallow faults produce earthquakes in the upper 18 miles (30 kilometers) of the Earths crust. Whats up with the 50 US nuclear bombs stored at the Incirlik Air Base in Turkey, right on the same fault line California hasnt seen a catastrophic earthquake recently. Surface Geology | WA - DNR 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. Expect and help to extinguish fires. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. 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. But opting out of some of these cookies may affect your browsing experience. 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. 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. Proceed cautiously once the earthquake has stopped. 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. This category only includes cookies that ensures basic functionalities and security features of the website. These faults and earthquakes occur in the continental crust of North America. The Richter scale was developed in southern California in 1935 and was based on the local ground motion. 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. But the mapping offered geological clues that the newly found fault was indeed capable of future quakes. This is an active fault.. This is sometimes called "The Big One" by news media. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. The Survey conducts and publishes geologic mapping to identify and characterize faults throughout the state. This northwest-trending fault comprises a broad (as wide as 6-11 km), steep, northeast-dipping zone that includes several splays with inferred strike-slip, reverse, and thrust displacement. Many low-lying areas have wet soil or sediment beneath them that could liquefy during earthquakes. A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. A paleoseismologist will look for surface ruptures along faults and may use carbon-14 dating to learn when the rupture happened. Maps. Its certainly not to scare you. These combination faults are called oblique faults and include the Seattle fault, southern Whidbey Island fault zone, and DarringtonDevils Mountain fault zone. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. <> 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. Like other faults, when enough stress builds up, the megathrust will rupture. An official website of the United States government. What are the most dangerous fault lines around Seattle - Strange Sounds Deformed recessional outwash deposits and Holocene deposits were exposed; three unconformities separated the units. A lock () or https:// means youve safely connected to the .gov website. California Department of Conservation. 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. His team wanted to find the rate of sea level rise along the shore. Share sensitive information only on official, secure websites. 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. Because they rupture at such great depth, their seismic energy is distributed over a large area. In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. 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." You also have the option to opt-out of these cookies. Reverse faults are usually steep and occur in regions of compression. 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. The shaking can damage or destroy buildings and other infrastructure. Not all faults are active. A baristas hand hovers over the bean grinder. The faults length depends on whom you ask, Sherrod said. Scientists are not sure how far east it goes. For earthquakes that occurred before seismographs were invented, the Mercalli Intensity scale was used to make maps of damage and determine the size and location of an earthquake. Photo courtesy of National Center for Tsunami Research, NOAA. 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. Do you know what to do if there is an earthquake? We pray for people of WA and our all north Americans as well. The most important thing you can do before the next earthquake is to prepare. Though it was not directly related to Johnsons work, he asked a friend working for Mobil Oil to pass along the information. Geologists are constantly trying to better understand the faults in our state. They havent dug up enough history to estimate. The 2011 Tohoku earthquake in Japan occurred on this type of fault and released enough energy to slightly change the Earths axis of rotation. Kristin D. Morell 1 *, Christine Regalla 2, Lucinda J. Leonard 3, Colin Amos 4, Vic Levson 5. The coast is now the home of one of the states largest network of warning sirens called All Hazard Alert Broadcast (AHABs). Earthquakes cause damage by moving and shaking the ground, sometimes for several minutes. (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. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. 1 NE 7th Street In the Pacific Northwest we use the term shallow to talk about faults and earthquakes less than 18 miles deep. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. 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. ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. Johnson and others . Tsunami waves can travel over 500 miles per hour in the open ocean. Identify and secure items in your home or work that could cause damage. The last time was 1,000 years ago between 900 and 903 A.D., said Forson. Finding and mapping these faults is an important mission of the Washington Geological Survey. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. America is going to be punished just like the rest of the world. Everything points to one thing, Sherrod said, waving his hand across the inland sea.

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