southern whidbey island fault map southern whidbey island fault map

The fault's length depends on whom you ask, Sherrod said. Washington State Earthquake Hazard Map. These faults and earthquakes occur in the continental crust of North America. Proceed cautiously once the earthquake has stopped. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. Videos: Strong M6.0 earthquake rattles Mindanao in the Philippines, Dramatic earthquake increase in Hawaii! The Survey conducts and publishes geologic mapping to identify and characterize faults throughout the state. This fault produces some of the largest and most damaging earthquakes in the world (M9). The Mercalli Intensity scale is another historical way to measure the intensity of an earthquake. In the 1990s, scientists producedan animationthat shows inundation, and people wont have much time to run to higher ground. He said he believes dramatic shifts from that quake also may be visible on the western edge of Camano Island. By finding the age of the deformed layer, a paleoseismologist can determine the minimum age of the fault. The Port of Coupeville will apply for a grant to fund two electric vehicle charging stations. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. Once the shaking has stopped, exit the building if it is safe to do so. HomePrograms and ServicesGeologyGeologic Hazards. The more you know what to expect, the better prepared you will be to help yourself, your family, and others around you. This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. 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. Consider whether earthquake insurance is right for you. While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. Most faults are considered active if they have evidence for movement (this includes earthquakes) within the past 12,000 years (the Holocene time period). What we know about this fault is that its ruptured may times in the pastit will happen again. It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. An earthquake occurs when rock inside the Earth moves or breaks. Watch the video below to learn how you can be ready for the next earthquake. This fault zone was originally named the Devils Stay inside until the shaking stops and it is safe to go outside. 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. This uplift creates a very broad wave called a tsunami. What about the localized tsunami risk? After large earthquakes there are usually many aftershock 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?? East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . Earthquakes on faults like these may cause tsunamis in the Puget Sound region. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. 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 Many low-lying areas have wet soil or sediment beneath them that could liquefy during earthquakes. An official website of the United States government. Maps. This diagram shows the many types of active faults and the general location of past earthquakes in Washington. The team also found that accumulated movement on the fault has uplifted old Snoqualmie River sediments to their current position on ridges, in some places several hundreds of feet above the modern Snoqualmie valley floor. The material becomes so weak that it behaves more like a liquid than a solid. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. 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. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> The shaking can damage or destroy buildings and other infrastructure. 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. The moment magnitude scale replaced the Richter scale in the late 1970s. 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. 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. One of these cracks appeared along the pathway around Green Lake. 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. 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). Map by And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. A thrust fault is a special kind of reverse fault that has a shallow dip. 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. For example, a building on soft soil will experience more shaking than the same building on bedrock. You will not be able to google what to do in an earthquake when it is happening. 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 . The buildings sank when ground shaking weakened the underlying sediments. 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 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 is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. The evidence shows each lake rests on different free-floating jigsaw pieces of planetary crust, separated by the southern Whidbey Island fault. South Whidbey fault has potential for major quake Consider subscribing to our blog, Washington State Geology News, to receive notifications when new information is published. However, we can learn which faults are active and which are inactive. 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. Roads, bridges, or ramps may have been damaged by the earthquake. Volcanic eruptions. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. 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). Also check out Ear to the Ground, published by the Department of Natural Resources. It startled Johnson that such massive faults had gone undetected for so long. ShakeMapGeologicSummaries - University of Washington The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. That place is the Ocosta School. Aftershocks can be nearly as large as the main earthquake and can cause significant additional damage. Prepare to be on your own for at least three days. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. Because after a region-wide event, it could take that long for help to come from the rest of the country and world. Deformed recessional outwash deposits and Holocene deposits were exposed; three unconformities separated the units. On a brilliant November day, Sherrod took in the panorama from the parks bluff. Necessary cookies are absolutely essential for the website to function properly. Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. Hundreds could die, with thousands more injured. The team determined that the Rattlesnake Mountain fault zone, originally mapped by DNR geologist Tim Walsh in the 1980s, is likely the southern continuation of the southern Whidbey Island fault, extending this fault zone from the Strait of Juan de Fuca to Rattlesnake Mountain near North Bend. In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. Quaternary Fault and Fold Database of the United States - USGS PDF Seismic Characterization of the Seattle and Southern Whidbey Island After the shaking stopped the sand regained its strength. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. 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. (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. For several years, scientists pondered where this important regional fault zone continues southwestward from its mapped location in the Everett area. These cookies do not store any personal information. 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. of Earth and Space Sciences, Box 351310, Univ. The affiliate sales will help us to continue the hard work we are putting in this website. 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. Once we got it, we were sort of shocked to see these big faults in the Puget lowlands, he said. The video is also available in Spanish and there is a fun activity/coloring book that can be found here. Expect and help to extinguish fires. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. The Moment Magnitude Scale (M) measures the total amount of seismic energy (known as moment to engineers and seismologists) released by an earthquake. % When the ground shakes during an earthquake, it moves up and down, acting like additional gravity. . In 1985, with little concrete evidence of its existence, the pair included the possible fault on a geologic map published by the USGS. Many faults have not been studied enough to know if they are active. Later movement on this long-term active fault zone cut the volcano. Puget Sound Earthquake Faults - Seattle Earthquake Faults 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. By clicking Accept, you consent to the use of ALL the cookies. The San Andreas fault in California is a good example of a very active strike-slip fault. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. They didnt recognize the significance of what they found. Faults are features in the Earths crust where rock periodically breaks and moves, releasing seismic energy and creating an 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. But it didnt. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. Hold on to any sturdy shelter until the shaking stops. So the fault remained mostly a mystery until the 1990s. We pray for people of WA and our all north Americans as well. Experts believe a magnitude 9.0 could happen there anytime in the next 200 years or so. PDF Cretaceous-Jurassic accreted terrains - University of Washington Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. Other faults may lie entirely underground, or could be covered by vegetation and (or) sediment. In Washington, the risk from earthquake-induced landslides is large. 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. 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. This map of gravity residuals measured over the puget lowland reveals a pattern of deep, fault bounded basins (cool colors) and uplifts (warm colors). A drill rig left of the blockade is collecting data about the failure. Charles Richter and Beno Gutenberg discovered that for every magnitude of earthquake, there are about ten times more earthquakes of the next lower magnitude. This map is from a 2007 report on the seismic design categories in Washington. The 2011 Tohoku earthquake in Japan occurred on this type of fault and released enough energy to slightly change the Earths axis of rotation. A lot of people are transplants, Forson said. ; (5) large-scale liquefaction features in upper Quaternary sediments within the fault zone; and (6) minor historical seismicity. The southern Whidbey Island fault zone (SWIF) is a mostly concealed, northwest-trending structure extending across southern Whidbey Island toward Vancouver Island (Figures 1 and 2). South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . When the landslide hit the water it may have created a tsunami. The Survey works to increase public and scientific understanding of fault and earthquake hazards in our state. Paleoseismologists have found places that record many of these tsunami deposits. Liquefaction can be a big problem. The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. What are the most dangerous fault lines around Seattle - Strange Sounds Emergency Management Maps - Island County, Washington After the shaking stopped the sand regained its strength. Finding and learning about faults requires many different aspects of geology and geophysics. 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. And when are documentary film called Cascadia The Big One, Dangerous Inland Earthquake Destroys Homes and Schools near Jakarta, Indonesia, Terrifying video shows olive grove turned into a Gigantic Canyon after Turkeys earthquake split land in huge rifts. Unlike sound, ground shaking can be amplified or attenuated (made less) depending on the type of material at the Earths surface. If a large earthquake happens, be prepared for many more earthquakes. 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. The height difference likely was caused by a 7.5 magnitude earthquake on the fault about 2,700 years ago, Sherrod said. This scenario was modeled on the part of the SWIF from Woodinville to just west of Whidbey Island. One of the best views of SWIF should be from Grand Avenue Park in Everett. Do you know what to do if there is an earthquake? For example, the DNR team found evidence that the rocks creating Snoqualmie Falls are much younger than previously thought. The team determined that the Rattlesnake Mountain fault zone, originally mapped by DNR geologist Tim Walsh in the 1980s, is likely the southern continuation of the southern Whidbey Island fault, extending this fault zone from the Strait of Juan de Fuca to Rattlesnake Mountain near North Bend. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Each of these aftershocks would be a significant earthquake if it happened on its own. 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. Radiocarbon dating and other paleoseismic methods have also confirmed this date. These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) Rogers Belt (Mount Vernon Fault/Granite Falls Fault Zone) Cherry Creek Fault Zone Rattlesnake Mountain Fault Zone Seattle Fault Tacoma Fault Saddle Mountain Faults 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. The years have gone by. Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. The western half of Washington state is considered earthquake country, with the potential for very large quakes. 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. PI22343). Visit our School Seismic Safety page for more information. All Rights Reserved 2021, Site Disclaimer 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. What are the most dangerous fault lines for Seattle? Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . USA Earthquake Hazard Map. 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 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. If everyone tries to use their cell phones, it can overload the system. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. 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. Johnson and others (1996 #4751) described the structure and stratigraphy of the southern Whidbey Island fault zone. This kind of grouping gives us information about how common earthquakes might be and how large an area may be affected. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. 1 0 obj During site visits in 2005, Sherrods team found evidence of four SWIF earthquakes in the past 30,000 years. PO Box 5000 Notable earthquakes in bold happened in Washington. For example, the Cascadia subduction zone has had between 15 to 19 earthquakes over the past 10,000 years. People stagger into the streets to avoid an avalanche of debris. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. The experts say few are ready. There are also tsunami evacuation signs on the highways. Finding faults and knowing how often they rupture is one of the most important tasks to keep society safe from these hazards. PDF Modeling a Magnitude 7.4 Earthquake on the Western Section of the After a large earthquake it is common to have other large earthquakes for hours, days, and even weeks. Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. Plate Tectonics | Pacific Northwest Seismic Network Landslide at Salmon Beach was triggered by the 1949 Tacoma earthquake and caused a tsunami. Tohoku killed nearly 16,000 people; most died as a result of drowning or being crushed in the tsunami. Another big one is expected, and it could be devastating. There are also many faults that have not been studied enough to know if they are active. DO NOT get in a doorway. Faults often occur at and near the boundary of large tectonic plates because the plates are moving in different directions. In general, larger faults make larger earthquakes. Within minutes, he spotted something groundbreaking. We also use third-party cookies that help us analyze and understand how you use this website. With Medical Martial Law imposed in Washington state. The southern Whidbey Island fault divides the two. Devils Mountain Fault -- Online Professional Paper - USGS The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. A .gov website belongs to an official government organization in the United States. There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. Bookcases and china cabinets topple, trapping people beneath. Standing becomes almost impossible as the jolts turn to rolling waves. This evidence can come from finding something younger than 12,000 years that has been deformed or moved by the fault. Hover over a cluster of earthquakes to learn about the different types in the Pacific Northwest. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). View of the Sunset Lake liquefaction failure about three weeks after the earthquake. Johnson and others . An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. Reverse faults are usually steep and occur in regions of compression. . In addition, the Survey performs seismic safety evaluations of schools. 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. One model suggests it extends to about 30 miles east of Yakima. Its just the way scientists work, he said. Johnson et al. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington.