southern whidbey island fault map

But Forson says you also need to know what to do when the shaking happens. These cookies do not store any personal information. This website uses cookies to improve your experience while you navigate through the website. Seismologists estimate that such quakes and tsunami waves occur roughly every 500 years on average on the Cascadia Subduction Zone. The southern Whidbey Island fault represents a segment of a boundary between two major crustal blocks. 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. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. Electricity, water, natural gas, and phones may not work. 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. Much of the land along the southwestern part of the lake cracked and subsided. It could also create dangerous currents and hazards to the north including Everett. These cookies will be stored in your browser only with your consent. It will happen; we dont know when.. 1 NE 7th Street This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). It is mandatory to procure user consent prior to running these cookies on your website. This car was parked on sand during the 2011 earthquake in Christchurch, New Zealand. An increase of 2 means that ~1,000 times more energy is released. Evacuate to higher ground if you are near a large body of water. The continued movement along faults over millions of years can build mountains, tear a continent apart, and move tectonic plates thousands of miles. Drop, Cover, and Hold On whenever you feel shaking. Landslide at Salmon Beach was triggered by the 1949 Tacoma earthquake and caused a tsunami. 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. The tsunamis can travel far inland and deposit layers of sand and organic material. During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. Many universities and other organizations (such as Cascadia Region Earthquake Working Group and the Pacific Northwest Seismic Network) also work to understand active faults in Washington. Keaton and Perry (2006 #7653) excavated two trenches on the south end of the Brightwater treatment plant (KP1 site 572-3, and KP2 site 572-4). Finding nothing of serious monetary value, the companies abandoned reams of information they had gathered through seismic surveys. The southern Whidbey Island fault zone (SWIF), as previously mapped using borehole data, potential field anomalies, and marine seismic reflection surveys, consists of three subparallel, northwest trending strands extending ~100 km from near Vancouver Island to the northern Puget Lowland. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. Higher risk areas are in orange and lower risk areas are in green. If the epicenter is Everett, the SWIF could cause. You saw its potential in the 9.1 magnitude Tohuku earthquake and tsunami that hit northeastern Japan in March 2011. Get On The List To Receive Your Daily Dose Of Weird News And Amazing Phenomena. This averages to ~660 to 525 years between events, but there is a lot of variation. The San Andreas in California, for example, left gaping scars in the Earths crust, at the surface. People stagger into the streets to avoid an avalanche of debris. What scientists dont know is its timing interval. Seattle Fault Lines. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. Though it was not directly related to Johnsons work, he asked a friend working for Mobil Oil to pass along the information. The Port of Coupeville will apply for a grant to fund two electric vehicle charging stations. Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. In fact, new faults are found every year during our geologic mapping efforts. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. That could spell trouble not only for its namesake island but for south and north King County and further west. Because they rupture at such great depth, their seismic energy is distributed over a large area. 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. PO Box 5000 Johnsons curiosity changed the course of his career. These sediments were laid down 20,000 to 60,000 years ago, before the last ice age. They havent dug up enough history to estimate. Expect aftershocks. Oil companies descended in search of riches. Although we know much about active faults and earthquakes, there is much more to learn. Liquefaction can be a big problem. When this happens, even a very small slope can cause the ground to slide. Even if the earthquake is too small to be felt by people, seismographs can detect it. Faults can be grouped based on their relative movement into three types. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. A lock () or https:// means youve safely connected to the .gov website. This fault will have an earthquake in the future, but we cannot predict exactly when. Third, the South Whidbey Island Fault running from northwest to southeast of the southern tip of the island. endobj Sherrods son has since completed graduate school in applied geosciences. Do you know what to do if there is an earthquake? Theres an uneasy hush. One model suggests it extends to about 30 miles east of Yakima. In the early 2000s, USGS scientists including Brian Sherrod set out to further Johnsons work and better understand the slumbering fissure. This uplift creates a very broad wave called a tsunami. The South Whidbey Island Fault and Darrington Devil's Mountain Fault bound the Everett Basin. The Cascadia subduction zone just off the Washington coast is this kind of fault and is one of the largest geologic hazards to our state. Once we got it, we were sort of shocked to see these big faults in the Puget lowlands, he said. Other faults are inactive and are left over from much older periods of deformation. Sherrod remembers his son, age 5 at the time, playing with toy trucks on the mossy banks of the marsh while the scientists worked. 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. Although we cannot predict exactly when the next earthquake will happen, we can predict the general distribution of earthquake sizes. For example, the Cascadia subduction zone has had between 15 to 19 earthquakes over the past 10,000 years. A reverse fault occurs when two blocks are pushed together and one moves up and over the other. We pray for people of WA and our all north Americans as well. A 2014 map shows what we know about the age of faults in Washington. Expect and help to extinguish fires. /L\Axc4Q/w4Ks^#, sRITgZf>,e}iI5,F_ADGc?f e@L. But they didnt document it hardly at all.. HOLOCENE FAULT SCARPS AND SHALLOW MAGNETIC ANOMALIES ALONG THE SOUTHERN WHIDBEY ISLAND FAULT ZONE NEAR WOODINVILLE, WASHINGTON By Brian L. Sherrod1, Richard J. Blakely2, Craig Weaver1, Harvey Kelsey3, Elizabeth Barnett1, and Ray Wells4 1 U.S. Geological Survey, Dept. In the late 1960s, speculators considered the Puget Sound region a frontier for petroleum exploration. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. 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 Seattle fault is a good example of a fault that is mostly reverse. . Photo from Pacific Northwest Seismic Network Seismo Blog. 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 Within this rich oral history there are many references to events like earthquakes and tsunamis. The combination of all of these effects is what makes earthquakes such a powerful geologic hazard. 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. Earthquakes between 45 and 185 miles deep are called intermediate, and earthquakes over 185 miles deep are called deep. Discover in this article the most dangerous earthquake zones for Seattle and its area: The Cascadia Subduction Zone, the Seattle Fault and the South Whidbey Island Fault. 572 Last Review Date: 2016-11-29 It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. A damaging earthquake is inevitable on this fault, but we do not know exactly when it will happen. The 1964 M9.2 Alaska earthquake created a large tsunami from the fault rupture, and many smaller tsunamis from on-land and underwater landslides. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. 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. 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). In general, larger faults make larger earthquakes. The Eastern Sierra fault along the east side of the Sierra Nevada mountains in California is a good example of an active normal fault. Both types of faults can cause ground shaking during an earthquake and may cause permanent deformation of the ground. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. In the 1990s, scientists producedan animationthat shows inundation, and people wont have much time to run to higher ground. 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. Fir trees near the failure are tilted and indicate rotation into the lake (to the left of the photo). Radiocarbon dating and other paleoseismic methods have also confirmed this date. Since about 1870 there have been about 15 large earthquakes (greater than M5) in the state. 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). The Safe America Foundation suggests texting as a way of communication. The strength of ground shaking (called strong motion by seismologists) usually decreases with distance from the earthquake source. Hold on to any sturdy shelter until the shaking stops. A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . Each of the earthquakes listed on the bottom of the screen is capable of significant damage. Consider a magnitude 7.4 quake with Whidbey Island at or near the epicenter. The height difference likely was caused by a 7.5 magnitude earthquake on the fault about 2,700 years ago, Sherrod said. Faults are features in the Earths crust where rock periodically breaks and moves, releasing seismic energy and creating an earthquake. Avoid stopping near or under buildings, trees, overpasses, or utility wires. endobj 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. southern Whidbey Island fault zone (Class A) No. Some of these faults are in remote areas. The South Whidbey Island Fault is also dangerous. Small fires are the most common hazard after an earthquake. In this photo, visitors to Green Lake Park near Seattle, Washington, have parked their bicycles as they look at the cracks made by the April 1949 earthquake. Depending on the type of fault, the ground can move laterally, vertically, or a combination of both. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. <> Once the shaking has stopped, exit the building if it is safe to do so. This map of gravity residuals measured over the puget lowland reveals a pattern of deep, fault bounded basins (cool colors) and uplifts (warm colors). Maps. 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. However, we can learn which faults are active and which are inactive. The southern Whidbey Island fault divides the two. Be prepared and read more on DNR, USGS, King5, Strange Sounds and Steve Quayle. The most recent hit roughly 2,700 years ago. 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. After a large earthquake it is common to have other large earthquakes for hours, days, and even weeks. Geologists do not yet know how often earthquakes happen on this fault. People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). These older faults do not have any evidence for recent activity, but the Earth is always changing. Know what other hazards you might face. 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 We use the term deep to talk about faults and earthquakes deeper than about 18 miles. Scientists have been trying to understand how often earthquakes happen for over 100 years. Never use a lighter or match near damaged areas. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. The map is from a 2007 report (click here to download) on seismic design categories in Washington. Stratigraphy in the Flying Squirrel trench showed gentle warping of late glacial and post-glacial sediments; no faults were exposed. Ready to retrofit? 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). Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. This earthquake caused parts of Restoration Point near on Bainbridge Island to be lifted 35 feet straight up. The Richter scale was developed in southern California in 1935 and was based on the local ground motion. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. Knowing how often large earthquakes have happened in the past helps us to know how often they might occur in the future. #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. This can cause landslides to occur where they wouldnt normally happen. Even places that are far from active faults are still at risk during a large Cascadia subduction zone earthquake. 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. There must be tsunami deposits of the same age along much of the Oregon and Washington coast in order to qualify as an earthquake. Both of these things can cause equal or greater damage than the actual earthquake. The Survey has developed several types of hazard maps for different types of earthquake- and fault-related hazards: The maps are used by state and local governments to develop and update hazard-mitigation and response plans, and to mark geologically hazardous areas. USA Earthquake Hazard Map. The Mercalli Intensity scale is another historical way to measure the intensity of an earthquake. 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. Consider whether earthquake insurance is right for you. Make an emergency response plan for you and your family. All faults, regardless of size, can be dangerous if they rupture. Necessary cookies are absolutely essential for the website to function properly. The Geologic Information Portal has a Natural Hazards theme that shows active faults and earthquakes. There are also tsunami evacuation signs on the highways. Its certainly not to scare you. In the Pacific Northwest we use the term shallow to talk about faults and earthquakes less than 18 miles deep. Latest earthquakes map and list (past 24 hours, M2.5+) from the ANSS (Advanced National Seismic System). Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. Bookcases and china cabinets topple, trapping people beneath. Along the coast residents may have between 20 and 30 minutes to get to higher ground. After large earthquakes there are usually many aftershock earthquakes. 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. For the most up-to-date information, please refer to the interactive fault map. 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). Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. A seiche is a large standing wave caused by the resonance of a particular period of wave energy. These quakes are capable of magnitudes from 7 to over 9. . The plate that is forced down can have faults within it that still rupture and produce earthquakes. (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. We work closely with the Washington Emergency Management Division, the Washington Seismic Safety Committee, and the Federal Emergency Management Agency to ensure that the best-available science is used in the development of hazard mitigation plans. Other types of seismic energy (S waves) also travel through the earth, but they move with a side-to-side (shearing) motion. With Medical Martial Law imposed in Washington state. Most are too small to be felt or cause damage. The friend obliged. 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. Its just the way scientists work, he said. Most injuries occur when people inside change rooms or try to leave the building. Armentrout, J. J. Miller, C. Finn, C. S. Weaver. He said scientists have known about the southern Whidbey fault for decades. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. During site visits in 2005, Sherrods team found evidence of four SWIF earthquakes in the past 30,000 years. Its significantly larger than the Seattle Fault, and South Whidbey could hand us a magnitude 7.5 earthquake. This map shows different seismic design categories that correlate with amount of seismic risk. You also have the option to opt-out of these cookies. When a fault with vertical movement ruptures the ocean floor, it lifts up part of the ocean. What are the most dangerous fault lines for Seattle? This date was confirmed by records in Japan of an orphan tsunami and by many lines of geologic evidence. Proceed cautiously once the earthquake has stopped. The map also shows potentially active faults from a separate 2014 report (click here to download). A low-angle fault, which is not conclusively earthquake related, separates a diamicton from the overlying recessional outwash deposit. All Rights Reserved 2021, Site Disclaimer 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. Tsunamis are a common result of large earthquakes in Washington. Stay away from glass, windows, outside doors and walls, and anything that could fall down. 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. 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. 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 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. Others, like the Seattle fault and southern Whidbey Island fault zone, cross under major cities and pose a significant hazard. The age of the earthquake is learned by dating the organic material in these tsunami deposits. Some faults reach the surface and can be found by geologists. It forms the northern boundary of the Everett basin and lies along a series of high-amplitude aeromagnetic anomalies that extend from the Cascade Mountains to Vancouver Island, B.C. Identify and secure items in your home or work that could cause damage. Save my name, email, and website in this browser for the next time I comment. This diagram shows the many types of active faults and the general location of past earthquakes in Washington. (Andy Bronson / The Herald). The most important thing you can do before the next earthquake is to prepare. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. 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. These types of faults are common, but usually small. Doctor reveals the horrors Italian medics are facing in overwhelmed hospitals where dying patients are being left untreated as experts warn UK and US are just two weeks behind Italy and the public are not SCARED enough, An intensive care doctor in northern Italy has described the scale of the crisis Often this cracking happens because a soft part of the ground liquefies during the shaking. He said he believes dramatic shifts from that quake also may be visible on the western edge of Camano Island. A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. Tsunami waves can travel over 500 miles per hour in the open ocean. 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. Check out the liquefaction susceptibility and NEHRP site class maps on the Geologic Hazard Maps page. This means that a large area feels the shaking, but the intensity is less than a similar shallow earthquake. @\;L;=}%FC*l $@ 4x: 888O~xrsxx'/*rGRF\gI%~x(G-^-hjjq kx/V ou0hyegy0;ei`Tx&ilZ )TmZ$vb,`bQm|DR5x/ 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. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). They conclude the observed features have a glaciotectonic origin and are not seimotectonic. This is similar to how sound is quieter when you move away from a speaker. The southern Whidbey fault is shallow, running right under Snohomish County as opposed to many miles off shore like the Cascadia fault. You have entered an incorrect email address! An abrupt rise or decline in sea level would reveal if the fault had triggered a quake before. Paleoseismologists have found places that record many of these tsunami deposits.

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southern whidbey island fault map