Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. Image from the, Aquatic Lands Habitat Restoration Program, South Lake Washington Restoration Project, Scientific and Technical Support to Aquatic Programs, Washington Geologic Survey Publications Catalog, Washington Geologic Survey Photograph Collection, Wetlands of High Conservation Value Map Viewer, Timber Sale Remaining Volume by Purchaser Reports, Spanish - Brocha, Salal y Otros Productos Forestales, Complete: Baker to Bellingham Non-Motorized Recreation Plan, Community Wildfire Resilience and Preparedness, Utility Wildland Fire Prevention Advisory Committee, Blanchard, Reiter, Walker Valley and Nearby Islands, Teanaway Community Forest Advisory Committee, Teanaway Community Forest Advisory Committee Past Meetings, Faults and Earthquakes in Washington State, Pacific Northwest Seismic Network Seismo Blog, https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg, Pacific Geoscience Center of the Natural Resources of Canada. 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. Not all faults are active. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. 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 faults length depends on whom you ask, Sherrod said. 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. The South Whidbey Island Fault is also dangerous. Deep faults can occur where two tectonic plates collide and one of the plates is forced beneath the other. Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. You also have the option to opt-out of these cookies. After large earthquakes there are usually many aftershock earthquakes. An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. Disoriented drivers wonder whats wrong with their cars, then realize something much bigger is amiss. 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. 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. 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 Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. 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. Power could be out for days. Floods. of Earth and Space Sciences, Box 351310, Univ. Earthquakes occur nearly every day in Washington. Johnson and others (1996 #4751) described multiple sub-parallel strands and referred to the overall structure as the "southern Whidbey Island fault zone," and this name is also used herein for this zone of faults that crosses the southern part of Whidbey Island. Contact Us, Whidbey Office Johnson et al. In some areas getting up a hill to higher ground will be difficult. Even when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. The marshy deposits are about a meter higher at Lake Hancock. A national credit rating service has improved its opinion of WhidbeyHealths financial future. Experts believe a magnitude 9.0 could happen there anytime in the next 200 years or so. In the early 2000s, USGS scientists including Brian Sherrod set out to further Johnsons work and better understand the slumbering fissure. 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. Each type has different kinds of earthquakes. Superior Court:(800) 254-2755 Before modern record keeping, Native Americans lived in the Pacific Northwest for thousands of years. Johnson and others (1996 #4751) described the structure and stratigraphy of the southern Whidbey Island fault zone. Scientists dont know. Ground shaking is a hazard near the epicenter of an earthquake and also in areas far from the earthquake where amplification occurs. Even places that are far from active faults are still at risk during a large Cascadia subduction zone earthquake. Scientists at the Washington Geological Survey, the U.S. Geological Survey, universities, and many private geologic consulting firms work diligently to understand how often earthquakes happen on various faults throughout 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. These maps are created by small planes that use a specific type of laser to measure the elevation of the ground. 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. 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. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. 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. Its just the way scientists work, he said. Although we know much about active faults and earthquakes, there is much more to learn. (1999 . The map is from a 2007 report (click here to download) on seismic design categories in Washington. 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 (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . The study of seismic waves is called seismology and has allowed scientists to learn much about the internal structure of the Earth. " A lot of people are transplants, " Forson said. Most injuries occur when people inside change rooms or try to leave the building. Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. Check out the liquefaction susceptibility and NEHRP site class maps on the Geologic Hazard Maps page. 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. Paleoseismologists have found places that record many of these tsunami deposits. A strike-slip fault occurs when two blocks move past each other. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. %PDF-1.5 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. Westport currently is the only location with a vertical evacuation structure designed for a tsunami. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. 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. Evacuate to higher ground if you are near a large body of water. 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. 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. 3 0 obj For example, a building on soft soil will experience more shaking than the same building on bedrock. These types of faults are common, but usually small. 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. The fault's length depends on whom you ask, Sherrod said. Proceed cautiously once the earthquake has stopped. Photo from Pacific Northwest Seismic Network Seismo Blog. Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. They havent dug up enough history to estimate. Washington has dozens of active faults and fault zones. (360) 678-5111 This date was confirmed by records in Japan of an orphan tsunami and by many lines of geologic evidence. In the area of North Bend, the fault zone is 4 miles wide and consists of a series of parallel faults. Many landslide-prone areas of Washington are also located near active faults. <> Someone screams. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Because Japan was so well prepared, mostretrofitted buildingsoutside of the tsunami zone survived. 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. Knowing how often large earthquakes have happened in the past helps us to know how often they might occur in the future. Camano Island, WA 98282, Mailing Address Roads, bridges, or ramps may have been damaged by the earthquake. The Cascadia subduction zone last ruptured over 300 years ago on January 26, 1700. The Cascadia subduction zone off the Washington and Oregon coast is capable of some of the largest earthquakes in the world. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. Washington has few large normal faults because it is mostly in a region of compression. The southern Whidbey Island fault (SWIF) stretches from the vicinity of Victoria, B.C., across Puget Sound as far as the Cascade Range. 1 NE 7th Street A pair of scientists with the U.S. Geological Survey first theorized that a fissure between two major blocks of the earths crust might run through this slice of Puget Sound. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. Many faults have not been studied enough to know if they are active. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. 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). He said he believes dramatic shifts from that quake also may be visible on the western edge of Camano Island. 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 Were working on pedestrian evacuation maps that show the best routes for pedestrians to take to evacuate, said Forson. 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. But scientists theorize that the area has suffered only four . Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. Each peak of the Olympics stuck out with picturesque clarity in the distance. But opting out of some of these cookies may affect your browsing experience. The years have gone by. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. 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. This map shows different seismic design categories that correlate with amount of seismic risk. A thrust fault is a special kind of reverse fault that has a shallow dip. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. Until much more recently, no one really understood what it could do to a region of over 4 million people. Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. A half dozen people reaching for the last can of soup, someone could lose their life over that. 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. 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. Theres approximately a 14% chance of another approximately M9 earthquake occurring in the next 50 years. Reverse faults are usually steep and occur in regions of compression. If you are in bed: STAY there and COVER your head and neck with a pillow. The medic said colleagues were becoming sick and emotionally overwhelmed Strabge sounds very good report thanks a lot. Ready to retrofit? Most are too small to be felt or cause damage. An earthquake can be a scary event. Some parts of major cities (including Seattle, Tacoma, and Olympia) have been built on land that was reclaimed from soft and wet tidal ocean areas. 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. You will not be able to google what to do in an earthquake when it is happening. 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.

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