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One model suggests it extends to about 30 miles east of Yakima. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. Earthquakes can trigger landslides and tsunamis which can happen after the main event. Oil companies descended in search of riches. Some faults reach the surface and can be found by geologists. The San Andreas in California, for example, left gaping scars in the Earths crust, at the surface. Once the shaking has stopped, exit the building if it is safe to do so. Floods. Cover your head and neck with your arms to protect against falling debris. Scientists are not sure how far east it goes. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. Evidence for Quaternary movement on the southern Whidbey Island fault includes (1) offset and disrupted upper Quaternary strata imaged on seismic-reflection profiles; (2) borehole data that suggests as much as 420 m of structural relief on the Tertiary-Quaternary boundary in the fault zone; (3) several meters of displacement along exposed faults in upper Quaternary sediments; (4) late Quaternary folds with limb dips of as much as ???9?? Close to shore, this same wave could reach heights of 30100 feet or more. Why you should be prepared: 3 big earthquake threats in PNW endobj 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. Prepare to be on your own for at least three days. But scientists theorize that the area has suffered only four . Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. 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. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. Contact Us, Whidbey Office By finding the age of the deformed layer, a paleoseismologist can determine the minimum age of the fault. Its just the way scientists work, he said. 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. 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. The SWIF has been assessed by the USGS as capable of generating the largest crustal earthquake in Puget Sound. Sherrods son has since completed graduate school in applied geosciences. 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. 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. This earthquake caused parts of Restoration Point near on Bainbridge Island to be lifted 35 feet straight up. Although we know much about active faults and earthquakes, there is much more to learn. Johnson and others (1996) have described the southern Whidbey Island fault ( figure 1) as a broad (6 - 11 km) transpressional zone comprising three main splays, within which the local late Quaternary uplift rate is at least 0.6 mm/yr. Avoid stopping near or under buildings, trees, overpasses, or utility wires. Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. Maps. Restoring tap water to some homes could take over a year. Proceed cautiously once the earthquake has stopped. South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. 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. 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 magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . Emergency Management Maps - Island County, Washington 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. The coast is now the home of one of the states largest network of warning sirens called All Hazard Alert Broadcast (AHABs). The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. But opting out of some of these cookies may affect your browsing experience. And experts fear it could be even worse than The Big One.. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. In general, larger faults make larger earthquakes. It will happen; we dont know when.. Save my name, email, and website in this browser for the next time I comment. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. Each of the earthquakes listed on the bottom of the screen is capable of significant damage. Do you know what to do if there is an earthquake? Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. Liquefaction has caused significant damage during earthquakes in Washington. The South Whidbey Island Fault and Darrington Devil's Mountain Fault bound the Everett Basin. People stagger into the streets to avoid an avalanche of debris. 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. Each year we map additional areas and learn more about existing faults and (or) discover new ones. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. Washington State Earthquake Hazard Map. You also have the option to opt-out of these cookies. 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 . Secure .gov websites use HTTPS The Seattle fault last ruptured about 1,100 years ago in AD 900950. Southeast Extension of the Southern Whidbey Island Fault By Human Capital March 19, 2019. sw_whidbeyfault_rev122706.pdf (28.68 KB) The tsunamis can travel far inland and deposit layers of sand and organic material. USA Earthquake Hazard Map. The Westport area is now the first in North America to have acommunity vertical evacuation structure, a building strong enough to resist earthquake and tsunami wave forces and give people a platform above the expected wave heights. For some active faults, such as the Seattle fault or Cascadia subduction zone, we can also learn how often large earthquakes have happened in the past. The plate that is forced down can have faults within it that still rupture and produce earthquakes. Quake fault under Whidbey linked to potential mainland dangers Photo courtesy of MOHAI (neg. Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. 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. The Eastern Sierra fault along the east side of the Sierra Nevada mountains in California is a good example of an active normal fault. Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . Know what to expect. Earthquake Hazard Maps | Sound Seismic Washington, Seattle, WA 98195 2 U.S. Geological Survey, 345 Middlefield Road, M/S . The moment magnitude scale is a type of logarithmic scale, where each increase of 1 means ~32 times more energy is released. The Seattle Fault is also likely to create a tsunami that would inundate Harbor Island and much of SODO, Interbay, and the waterfront. Sherrod shrugged his shoulders. This was a problem because no two locations would agree on the size of the same earthquake. But they didnt document it hardly at all.. The last large earthquake on the Cascadia subduction zone was in 1700. Sherrod says practically every place they. 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. Moving inland, the Seattle Fault is capable of a magnitude 7. Areas like these are also susceptible to liquefaction. This is an active fault.. View Earthquake Map Faults Interactive fault map and comprehensive geologically based information on known or suspected active faults and folds in the United States. The map also shows potentially active faults from a separate 2014 report (click here to download). An official website of the United States government. The fault, not so much. This can cause landslides to occur where they wouldnt normally happen. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. 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. Emergency Management Hazard Maps - Island County, Washington Brick chimneys cascade off rooftops. The Survey conducts and publishes geologic mapping to identify and characterize faults throughout the state. Once in the open, Drop, Cover, and Hold On. Coupeville, WA 98239, Camano Office However, we can learn which faults are active and which are inactive. Stay inside until the shaking stops and it is safe to go outside. These faults and earthquakes occur in oceanic crust as it is subducted beneath the continent. After the earthquake, many things you count on may not be available. PDF Holocene Fault Scarps and Shallow Magnetic Anomalies Along the Southern 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. The best thing you can do is to become prepared. A .gov website belongs to an official government organization in the United States. Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. 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. PDF Modeling a Magnitude 7.4 Earthquake on the Western Section of the You saw its potential in the 9.1 magnitude Tohuku earthquake and tsunami that hit northeastern Japan in March 2011. Geoscientist Brian Sherrod stands near the submerged southern Whidbey Island fault line at the Brightwater Treatment Plant in Woodinville. Clicking on the map will download the publication. This category only includes cookies that ensures basic functionalities and security features of the website. Seattle's Faults: Maps That Highlight Our Shaky Ground This map of gravity residuals measured over the puget lowland reveals a pattern of deep, fault bounded basins (cool colors) and uplifts (warm colors).