The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. Paleoseismologists have found places that record many of these tsunami deposits. The southern Whidbey Island fault (SWIF) stretches from the vicinity of Victoria, B.C., across Puget Sound as far as the Cascade Range. Washington has the second highest risk in the U.S. of these large and damaging earthquakes because of its geologic setting. This map is from a 2007 report on the seismic design categories in Washington. 3 0 obj PDF Holocene Fault Scarps and Shallow Magnetic Anomalies Along the Southern Because after a region-wide event, it could take that long for help to come from the rest of the country and world. Volcanic eruptions. Do not exit a building during the shaking. 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 map shows different seismic design categories that correlate with amount of seismic risk. Scientists have been trying to understand how often earthquakes happen for over 100 years. Sherrod says practically every place they. 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. While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. The fault's length depends on whom you ask, Sherrod said. The shaking can damage or destroy buildings and other infrastructure. But opting out of some of these cookies may affect your browsing experience. What are the most dangerous fault lines for Seattle? You saw its potential in the 9.1 magnitude Tohuku earthquake and tsunami that hit northeastern Japan in March 2011. Standing becomes almost impossible as the jolts turn to rolling waves. These quakes are capable of magnitudes from 7 to over 9. Under a scenario played out in a 2019 U.S. Department of Homeland Security study, state-maintained bridges would be severely damaged, leaving them unusable for months or years. Bookcases and china cabinets topple, trapping people beneath. The combination of all of these effects is what makes earthquakes such a powerful geologic hazard. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . Sherrods son has since completed graduate school in applied geosciences. Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System). 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). That could spell trouble not only for its namesake island but for south and north King County and further west. The publication Faults and Earthquakes in Washington State is a state-wide compilation of active faults and folds. The bluff, where the cabins now sit, could have jutted up in the most recent Whidbey fault quake, Sherrod said. The DNR team found that the Seattle fault is intercepted by the southern Whidbey Island fault zone in the vicinity of Fall City. (Andy Bronson / The Herald). So the fault remained mostly a mystery until the 1990s. endobj For example, the DNR team found evidence that the rocks creating Snoqualmie Falls are much younger than previously thought. Source: United States Geological Survey. Once in the open, Drop, Cover, and Hold On. For example, the Cascadia subduction zone has had between 15 to 19 earthquakes over the past 10,000 years. It startled Johnson that such massive faults had gone undetected for so long. This new method allows geologists to see through trees and vegetation to find new faults. Most injuries occur when people inside change rooms or try to leave the building. Along the coast residents may have between 20 and 30 minutes to get to higher ground. 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. The map is from a 2007 report (click here to download) on seismic design categories in Washington. PDF Cretaceous-Jurassic accreted terrains - University of Washington A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. Much of the land along the southwestern part of the lake cracked and subsided. 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. Lidar maps show the Earths surface without vegetation. The medic said colleagues were becoming sick and emotionally overwhelmed The San Andreas in California, for example, left gaping scars in the Earths crust, at the surface. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault Theres an uneasy hush. Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. Earthquakes occur nearly every day in Washington. 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. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. Liquefaction has caused significant damage during earthquakes in Washington. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. PDF The Cottage Lake Aeromagnetic Lineament: a Possible Onshore Extension 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. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. Proceed cautiously once the earthquake has stopped. Contact Us, Whidbey Office In 1985, with little concrete evidence of its existence, the pair included the possible fault on a geologic map published by the USGS. % The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. This fault zone was originally named the Devils It could also create dangerous currents and hazards to the north including Everett. Notice the Seattle Fault Zone bounding the Seattle Basin to the south. Videos: Strong M6.0 earthquake rattles Mindanao in the Philippines, Dramatic earthquake increase in Hawaii! Emergency Management Earthquake - Island County, Washington However, we can learn which faults are active and which are inactive. The best thing you can do is to become prepared. Landslides can be caused by strong ground shaking during an earthquake. Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. 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. Not all faults are active. Fault Activity Map of California. Gower (1980 #6229) showed and named the "southern Whidbey Island fault," and Gower and others (1985 #4725) showed this fault on their seismotectonic map of the Puget Sound region and briefly outlined its geologic relationships. Drop, Cover, and Hold On whenever you feel shaking. The Seattle fault last ruptured about 1,100 years ago in AD 900950. An increase of 2 means that ~1,000 times more energy is released. The evidence shows each lake rests on different free-floating jigsaw pieces of planetary crust, separated by the southern Whidbey Island fault. This website uses cookies to improve your experience while you navigate through the website. HomePrograms and ServicesGeologyGeologic Hazards. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. An earthquake can be a scary event. What are the most dangerous fault lines around Seattle - Strange Sounds Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. The moment magnitude scale replaced the Richter scale in the late 1970s. All Rights Reserved 2021, Site Disclaimer For example, it is unlikely that you will be able to use electricity, cell phones, or the internet. Fir trees near the failure are tilted and indicate rotation into the lake (to the left of the photo). They didnt grow up here, they havent heard this story. PDF Modeling a Magnitude 7.4 Earthquake on the Western Section of the Scientists dont know. Notable earthquakes in bold happened in Washington. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. A reverse fault occurs when two blocks are pushed together and one moves up and over the other. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. 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." We also use third-party cookies that help us analyze and understand how you use this website. Roads, bridges, or ramps may have been damaged by the earthquake. Because they can travel great distances, tsunamis generated from earthquakes across the ocean can still cause damage. Sensitive seismographs located throughout the state, and all over the world, measure this seismic energy. 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. 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 Straight Creek fault in the Cascade Range is an example of this kind of fault and has ~5060 miles of movement across it. The more you know what to expect, the better prepared you will be to help yourself, your family, and others around you. 4 0 obj Many landslide-prone areas of Washington are also located near active faults. 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. Some residents may lose housing temporarily or permanently. A half dozen people reaching for the last can of soup, someone could lose their life over that. An earthquake occurs when rock inside the Earth moves or breaks. The southern Whidbey Island fault: An active structure in the Puget . Experts believe a magnitude 9.0 could happen there anytime in the next 200 years or so. The video is also available in Spanish and there is a fun activity/coloring book that can be found here. Finding faults and knowing how often they rupture is one of the most important tasks to keep society safe from these hazards. Also issued a warning for the UK that the Italian chaos could come to Britain In the month after the main earthquake there were about 60 M7 and M6 earthquakes. The trench did expose faults, but it was not possible to conclusively demonstrate offset of Holocene units. x\[s8~OU)! Still think well avoid Gods wrath, its not going to happen regardless of what the multi millionaire TV preachers tell you. Earthquakes can trigger landslides and tsunamis which can happen after the main event. Shallow faults produce earthquakes in the upper 18 miles (30 kilometers) of the Earths crust. Power could be out for days. The Seattle fault is a good example of a fault that is mostly reverse. Surface Geology | WA - DNR America is going to be punished just like the rest of the world. Earthquakes on shallow faults typically last 20 to 60 seconds and the shaking is localized to the general area of the fault. But it didnt. After the shaking stopped the sand regained its strength. Even when an earthquake happens on a fault that doesnt reach the surface, the ground can still show signs of cracking. 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. Emergency Management Hazard Maps - Island County, Washington Since about 1870 there have been about 15 large earthquakes (greater than M5) in the state. from Whidbey Island to Vancouver Island (Figure 1). 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. The marshy deposits are about a meter higher at Lake Hancock. Each type has different kinds of earthquakes. The moment magnitude scale is a type of logarithmic scale, where each increase of 1 means ~32 times more energy is released. The San Andreas fault in California is a good example of a very active strike-slip fault. ShakeMapGeologicSummaries - University of Washington People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). Geologists and geophysicists at the Washington Geological Survey map out these areas of amplification to help reduce damage during an earthquake. You just need one person to crash or a power line to fall over the road, and the roads are unusable.. In places where there is little vegetation, different rock types and faults can be found with relative ease. 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. These faults and earthquakes occur in oceanic crust as it is subducted beneath the continent. The map also shows potentially active faults from a separate 2014 report (click here to download). 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 is mandatory to procure user consent prior to running these cookies on your website. Floods. Quaternary Rupture of a Crustal Fault beneath Victoria, British With Medical Martial Law imposed in Washington state. 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. Consider whether earthquake insurance is right for you. Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. The southern Whidbey Island fault divides the two. Small fires are the most common hazard after an earthquake. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington. This map shows areas of seismic risk from high (red) to low (grayish-green). He combed through state and federal data to understand the risks, and to help train first responders. Over time, fault movement has created some interesting geologic features. Washington State Earthquake Hazard Map. Never use a lighter or match near damaged areas. It usually also means that there are earthquakes (even small ones) on the fault. Both studies suggested that the SWIF Ready to retrofit? When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. And what were looking at is water.. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. Stories from tribes near Seattle have also helped us to learn that the last earthquake on the Seattle fault was about AD 900950. When an earthquake happens there will not be time to google what you are supposed to do. Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface. Every year Western. When this happens, even a very small slope can cause the ground to slide. Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . Stay away from glass, windows, outside doors and walls, and anything that could fall down. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. Johnson and others . Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. 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. The map also shows potentially active faults from a separate 2014 report (click here to download). A .gov website belongs to an official government organization in the United States. People stagger into the streets to avoid an avalanche of debris. Other faults may lie entirely underground, or could be covered by vegetation and (or) sediment. Everything points to one thing, Sherrod said, waving his hand across the inland sea. Strait of Juan de Fuca Fault Map The Puget Sound faults under the highly populated Seattle and Puget Sound region of Washington state form a regional network of interrelated seismologic geologic faults. Earthquakes can be measured in many ways, but the most accepted method is called moment magnitude. Scientists are not sure how far east it goes. This diagram shows the many types of active faults and the general location of past earthquakes in Washington. . The Eastern Sierra fault along the east side of the Sierra Nevada mountains in California is a good example of an active normal fault. A paleoseismologist will look for surface ruptures along faults and may use carbon-14 dating to learn when the rupture happened. (1999 . Why is Strange Sounds focusing so much on disaster preps? This uplift creates a very broad wave called a tsunami. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. This was a problem because no two locations would agree on the size of the same earthquake. 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. They conclude the observed features have a glaciotectonic origin and are not seimotectonic. They didnt recognize the significance of what they found. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Geologists at the Survey spend time mapping the geology of the state, looking for faults, folds, landslides, and different rock types. 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. This is sometimes called "The Big One" by news media. Each of these aftershocks would be a significant earthquake if it happened on its own. In effect, the wave energy is trapped by the edges of the body of water. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. 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. The continued movement along faults over millions of years can build mountains, tear a continent apart, and move tectonic plates thousands of miles. You can look at different geological hazard mapson the website of the Department of Natural Resources. But scientists theorize that the area has suffered only four . The buildings sank when ground shaking weakened the underlying sediments. The French Onion trench exposed glaciolacustrine claystones, till, colluvial deposits, and Holocene soils. The next earthquake is inevitable, but the variability makes it difficult to know exactly when. Seattle's Faults: Maps That Highlight Our Shaky Ground A normal fault occurs when two blocks are pulled away from each other. For example, a M7 earthquake releases 32 times more energy than a M6 earthquake, and 1,000 times more than a M5 earthquake. That place is the Ocosta School. His team wanted to find the rate of sea level rise along the shore. Areas like these are also susceptible to liquefaction. Devastating wind storms. But Forson says you also need to know what to do when the shaking happens. Coupeville, WA 98239, Camano Office And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. There are also many faults that have not been studied enough to know if they are active. Secure .gov websites use HTTPS Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. Once the shaking has stopped, exit the building if it is safe to do so. This might include flammable appliances like a water heater, tall items like book cases, or heavy pictures. Quake fault under Whidbey linked to potential mainland dangers Stay inside until the shaking stops and it is safe to go outside. District Court: (800) 946-9765, South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario.