But they didnt document it hardly at all.. Even when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. Scientists have also dated large underwater landslides and turbidites that travel from the continental edge far out into the ocean basin. He said scientists have known about the southern Whidbey fault for decades. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. Hold on to any sturdy shelter until the shaking stops. Reverse faults are usually steep and occur in regions of compression. Hey Biden! This fault will have an earthquake in the future, but we cannot predict exactly when. Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . Earthquakes can trigger landslides and tsunamis which can happen after the main event. Liquefaction has caused significant damage during earthquakes in Washington. Scientists dont know. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. Most damage and loss of life in earthquakes is a result of ground shaking. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. The trench did expose faults, but it was not possible to conclusively demonstrate offset of Holocene units. Sometimes Geologists can use the offset land surface to understand how much the fault moved during the earthquake. Below you will find links to view and download hazard maps created for each jurisdiction included in the current mitigation planning process. Once in the open, Drop, Cover, and Hold On. On a brilliant November day, Sherrod took in the panorama from the parks bluff. The best thing you can do is to become prepared. 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. Floods. 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. 3 0 obj Devastating wind storms. 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. By sampling sediment from the marsh to the beach berm, Sherrod and his research partner, Harvey Kelsey, developed a timeline of the oceans climb. Secure .gov websites use HTTPS Nearly all earthquakes occur on faults, features in the Earth where rocks move past each other. 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 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. One of these cracks appeared along the pathway around Green Lake. Often this cracking happens because a soft part of the ground liquefies during the shaking. Every year Western. The 2011 Tohoku earthquake in Japan occurred on this type of fault and released enough energy to slightly change the Earths axis of rotation. In fact, new faults are found every year during our geologic mapping efforts. In general, larger faults make larger earthquakes. Most injuries occur when people inside change rooms or try to leave the building. On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. What are the most dangerous fault lines for Seattle? Secure .gov websites use HTTPS You also have the option to opt-out of these cookies. 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. Ground shaking is a hazard near the epicenter of an earthquake and also in areas far from the earthquake where amplification occurs. Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. Never use a lighter or match near damaged areas. 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. 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. /L\Axc4Q/w4Ks^#, sRITgZf>,e}iI5,F_ADGc?f e@L. Photo by Steve Palmer. Prepare to be on your own for at least three days. The map is from a 2007 report (click here to download) on seismic design categories in Washington. This new method allows geologists to see through trees and vegetation to find new faults. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault For example, the Cascadia subduction zone has had between 15 to 19 earthquakes over the past 10,000 years. A few miles southeast across the white-capped waves of Admiralty Bay, Lake Hancock rises and falls with the tides. Unlike The Big One, scientists who have studied the southern Whidbey fault have far less understanding of when the next sudden shift might hit. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. Theres an uneasy hush. The experts say few are ready. Consider whether earthquake insurance is right for you. 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 major earthquake was over 300 years ago. Sherrods son has since completed graduate school in applied geosciences. Hundreds could die, with thousands more injured. 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. Expect aftershocks. A normal fault occurs when two blocks are pulled away from each other. California Geological Survey. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. 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. Along the coast residents may have between 20 and 30 minutes to get to higher ground. The last large earthquake on the Cascadia subduction zone was in 1700. Because they can travel great distances, tsunamis generated from earthquakes across the ocean can still cause damage. Restoring tap water to some homes could take over a year. Throughout the world shallow earthquakes generally refer to earthquakes that are less than ~45 miles deep. 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 moment magnitude scale replaced the Richter scale in the late 1970s. Drop to your hands and knees. All faults, regardless of size, can be dangerous if they rupture. Bookcases and china cabinets topple, trapping people beneath. 552 - Hood Canal fault zone (Class B) 570 - Seattle fault zone 572 - Southern Whidbey Island fault zone 575 - Saddle Mountain faults 581 - Tacoma fault zone. 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. HomePrograms and ServicesGeologyGeologic Hazards. What about the localized tsunami risk? This is called liquefaction and is discussed in the next section. The fault zone is up to 57 km, correlates with gravity and magnetic anomalies (Finn and others, 1991 #4753; Blakely and others, 1999 #4747), and has been interpreted as a complex zone of transpressional deformation (Johnson and others, 1996 #4751). Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. 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. Sherrod remembers his son, age 5 at the time, playing with toy trucks on the mossy banks of the marsh while the scientists worked. Fir trees near the failure are tilted and indicate rotation into the lake (to the left of the photo). This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. 1 NE 7th Street Once a fault is located, it is important to know if it is active. Many faults have not been studied enough to know if they are active. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. The Seattle fault last ruptured about 1,100 years ago in AD 900950. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. The buildings sank when ground shaking weakened the underlying sediments. , * NOTE: Hazard maps for each jurisdiction will only be included if that jurisdiction is at risk to that hazard., Copyright Island County. One model suggests it extends to about 30 miles east of Yakima. Stay away from glass, windows, outside doors and walls, and anything that could fall down. It will happen; we dont know when.. 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). While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. Depending on the type of fault, the ground can move laterally, vertically, or a combination of both. Do you know what to do if there is an earthquake? Armentrout, J. J. Miller, C. Finn, C. S. Weaver. Drop, Cover, and Hold On whenever you feel shaking. When an earthquake happens there will not be time to google what you are supposed to do. 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. Standing becomes almost impossible as the jolts turn to rolling waves. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. Sherrod shrugged his shoulders. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. He combed through state and federal data to understand the risks, and to help train first responders. The French Onion trench exposed glaciolacustrine claystones, till, colluvial deposits, and Holocene soils. Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface. Tsunami waves can travel over 500 miles per hour in the open ocean. Geologic maps of 7.5-minute topographic quadrangles covering parts of the Seattle fault and southern Whidbey Island fault zone are available on the DNR website as: Sign-up for DNR enewsletters. There are also tsunami evacuation signs on the highways. The map is from a, This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. At the time, Johnson worked in southwest Washington, searching for natural gas and oil deposits. Faults can also occur within a tectonic plate when the plate itself is deforming. 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. Snohomish, King and Island counties would be expected to see the. Johnson and others (1996 #4751) described the structure and stratigraphy of the southern Whidbey Island fault zone. His team wanted to find the rate of sea level rise along the shore. However, seismic tomography studies (Brocher and others, 2001 #4718) reveal that only the northwestern end of the fault zone in the southeastern Strait of Juan de Fuca is associated with a strong velocity contrast. A lock () or https:// means youve safely connected to the .gov website. This kind of landslide is called an earthquake-triggered landslides. This is sometimes called "The Big One" by news media. 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. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. Higher risk areas are in orange and lower risk areas are in green. An earthquake occurs when rock inside the Earth moves or breaks. Some residents may lose housing temporarily or permanently. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. Theyre FREE CLICK HERE to subscribe, EAR TO THE GROUND WITH DNR & COMMISSIONER FRANZ, Tree Link helps you answer questions about urbantrees. The most recent hit roughly 2,700 years ago. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Washington has few large normal faults because it is mostly in a region of compression. The Seattle fault is a good example of a fault that is mostly reverse. Stop as quickly as safety permits and stay in the vehicle. Since about 1870 there have been about 15 large earthquakes (greater than M5) in the state. 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. Brick chimneys cascade off rooftops. 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 Theres approximately a 14% chance of another approximately M9 earthquake occurring in the next 50 years. (1999 . Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. Earthquakes. endobj High-resolution LiDAR topographic maps have since revealed several potential faults scarps, and subsequent studies provide more detailed information about the fault zone's past. However, we can learn which faults are active and which are inactive. Seismic waves travel at hundreds to thousands of miles per hour and quickly reach the surface where they are felt or measured. And being ready means being able to support yourself, your loved ones, your neighborhood for 2 weeks. After the earthquake, many things you count on may not be available. 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. Scientists are not sure how far east it goes. Photo from Pacific Northwest Seismic Network Seismo Blog. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. Hover over a cluster of earthquakes to learn about the different types in the Pacific Northwest. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. The Darrington-Devils Mountain fault zone is located in southern Skagit County and northern Snohomish County. A .gov website belongs to an official government organization in the United States. Resources on tsunami danger and preparedness in Westport, Grays Harbor County, Long Beach Peninsula, and Coastal evacuation maps. Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. endobj The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. Evacuate to higher ground if you are near a large body of water. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. That place is the Ocosta School. Dishes jitter off tables, shattering on the floor. The Cascadia Subduction Zone (also known as the CSZ) is a 700-mile long fault zone located off the western coastline of British Columbia, Washington, Oregon and northern California. Learn how your comment data is processed. Washington State Earthquake Hazard Map. Moving inland, the Seattle Fault is capable of a magnitude 7. #4747 Blakely, R.J., Wells, R.E., and Weaver, C.S., 1999, Puget Sound aeromagnetic maps and data: U.S. Geological Survey Open-File Report 99-514. They didnt recognize the significance of what they found. Aftershocks can be nearly as large as the main earthquake and can cause significant additional damage. A national credit rating service has improved its opinion of WhidbeyHealths financial future. South Whidbey Island Fault Zone. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. There are also many faults that have not been studied enough to know if they are active. Oblique convergence and clockwise rotation along the continental margin are the inferred driving forces for ongoing deformation. A lot of people are transplants, Forson said. This website uses cookies to improve your experience while you navigate through the website. This is a very good example of a strike-slip fault. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. Photo courtesy of MOHAI (neg. Do not exit a building during the shaking. The southern Whidbey Island fault divides the two. Until much more recently, no one really understood what it could do to a region of over 4 million people. They havent dug up enough history to estimate. But it didnt. Check out the liquefaction susceptibility and NEHRP site class maps on the Geologic Hazard Maps page. Mudslides. We do not encourage people to evacuate in vehicles. South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . This map is from a 2007 report on the seismic design categories in Washington. Electricity, water, natural gas, and phones may not work. After large earthquakes there are usually many aftershock earthquakes. For example, if there is one M7 earthquakes in an area every 1,000 years, then there will be about 10 M6 earthquakes, 100 M5 earthquakes, and 1,000 M4 earthquakes during the same 1,000 years. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. What we know about this fault is that its ruptured may times in the pastit will happen again. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. But quiet period wont last, Strongest earthquake in 40 years rattle residents of Buffalo, NY, Is Istanbul next? People stagger into the streets to avoid an avalanche of debris. In the Pacific Northwest we use the term shallow to talk about faults and earthquakes less than 18 miles deep. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. EVERETT The South Whidbey Island Fault is connected to a system of powerful earthquake fault lines stretching from Victoria, B.C., to Yakima that is capable of unleashing a devastating. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. Johnson and others . Johnson et al. Make an emergency response plan for you and your family. Coupeville, WA 98239, Camano Office An earthquake can be a scary event. Because they rupture at such great depth, their seismic energy is distributed over a large area. In Washington, we do not have tsunami walls. One model suggests it extends to about 30 miles east of Yakima. These differences are related to the overall pattern of stress in the crust, what types of rocks the crust is made from, and how many faults there are. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. 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. Jump from 60 to 600 per week in just 5 years in Pahala, Is the Cascadia Subduction Zone about to blow? But opting out of some of these cookies may affect your browsing experience. 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. Mapping along the Snoqualmie River valley also helped answer the important question of where the Seattle fault lies east of its last mapped position near Issaquah. Its certainly not to scare you. Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. At a downtown coffee shop, the mugs begin to chatter. The below map shows that Seattle and its surroundings is constantly being rattled by small earthquakes and tremors. 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." Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. A seiche is a large standing wave caused by the resonance of a particular period of wave energy. In the late 1960s, speculators considered the Puget Sound region a frontier for petroleum exploration. Please visit our Geologic Information Portal and Geologic Hazard Maps page for the most up-to-date listing of all of our hazard maps. The affiliate sales will help us to continue the hard work we are putting in this website. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. These cookies will be stored in your browser only with your consent. Volcanic eruptions. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. endobj Some of these faults are in remote areas. Sherrod says practically every place they. It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. A baristas hand hovers over the bean grinder. The faults length depends on whom you ask, Sherrod said. Since their initial discovery, research has shown that the actual number of earthquakes is somewhere between 5 and 10 for each change in magnitude. Know what to expect. Notable earthquakes in bold happened in Washington. On an inactive fault, the sea would have risen at the same rate at both locations. You have entered an incorrect email address! In 2017, he began studying the possible aftermath of a major SWIF quake. Others, like the Seattle fault and southern Whidbey Island fault zone, cross under major cities and pose a significant hazard. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. 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 from, Liquefaction can be a big problem. A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. The shaking can also cause landslides, surface ruptures, ground cracks, liquefaction, tsunamis, and seiches (standing waves). Source: United States Geological Survey. The average time between large earthquakes is about 535 years, but has been as little as 200 years, and more than 1,000 years. For example, a building on soft soil will experience more shaking than the same building on bedrock. Many landslide-prone areas of Washington are also located near active faults. The boundary between the two plates covers a large area and can lock together. The western half of Washington state is considered earthquake country, with the potential for very large quakes. But the Cascadia Subduction Zone isnt just a fault; its an overlapping joint between tectonic plates, parts of the Earths crust that float on layers of molten rock. Like other faults, when enough stress builds up, the megathrust will rupture. So they dont necessarily know the threats they face.. This date was confirmed by records in Japan of an orphan tsunami and by many lines of geologic evidence. Everything points to one thing, Sherrod said, waving his hand across the inland sea. <>>> But the mapping offered geological clues that the newly found fault was indeed capable of future quakes. 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. The southern Whidbey fault is unlike more visible faults on the West Coast.