southern whidbey island fault map southern whidbey island fault map

Expect aftershocks. Aftershocks can be nearly as large as the main earthquake and can cause significant additional damage. The Moment Magnitude Scale (M) measures the total amount of seismic energy (known as moment to engineers and seismologists) released by an earthquake. Geologists are constantly trying to better understand the faults in our state. Earthquakes on faults like these may cause tsunamis in the Puget Sound region. This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. Liquefaction is when wet soil or sediment loses strength because it is being shaken during an earthquake. endobj This map shows different seismic design categories that correlate with amount of seismic risk. You just need one person to crash or a power line to fall over the road, and the roads are unusable.. Emergency planners all had a simple message: Its not IF a disaster will happen, its WHEN. The experts say few are ready. This part of the Japanese coast had not seen this type of seismic rupture in some 800 years, and what failed was that walls built to keep tsunami waves were not high enough. The map is from a 2007 report (click here to download) on seismic design categories in Washington. The southern Whidbey fault is unlike more visible faults on the West Coast. California Geological Survey. If a large earthquake happens, be prepared for many more earthquakes. The risk is complicated, but there are millions of people who live in the Seattle area, said Forson. Identify and secure items in your home or work that could cause damage. Southeast Extension of the Southern Whidbey Island Fault, Washington: Implications for Earthquake Hazards, 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). One model suggests it extends to about 30 miles east of Yakima. 3 0 obj The fault's length depends on whom you ask, Sherrod said. Washington, Seattle, WA 98195 2 U.S. Geological Survey, 345 Middlefield Road, M/S . Also issued a warning for the UK that the Italian chaos could come to Britain 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. There are also tsunami evacuation signs on the highways. Because they can travel great distances, tsunamis generated from earthquakes across the ocean can still cause damage. One or possibly two of the unconformities are interpreted as event horizons. Click the "Seismogenic Features" button in the Map Contents window to display faults and earthquakes. California Department of Conservation. Finding and learning about faults requires many different aspects of geology and geophysics. Restoring tap water to some homes could take over a year. Scientists are not sure how far east it goes. An earthquake along the southern Whidbey Island fault reshaped the land some 2,700 years ago. Geologists have used the location of these shallow, intermediate, and deep earthquakes to learn about subduction zones throughout the world. This is sometimes called "The Big One" by news media. But the mapping offered geological clues that the newly found fault was indeed capable of future quakes. Even when the location of a fault is known, there is much additional work to determine how hazardous it may be. Still think well avoid Gods wrath, its not going to happen regardless of what the multi millionaire TV preachers tell you. These and other problems led to the search for a scale that was based on the physical processes that happen during an earthquake. <>/XObject<>/ExtGState<>/Pattern<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 612 792] /Contents 4 0 R/Group<>/Tabs/S/StructParents 0>> " A lot of people are transplants, " Forson said. 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. However, we can learn which faults are active and which are inactive. The more you know what to expect, the better prepared you will be to help yourself, your family, and others around you. 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. 1 NE 7th Street What we know about this fault is that its ruptured may times in the pastit will happen again. Know what other hazards you might face. The last earthquake on the Seattle fault (about AD 950) triggered a landslide and seiche in Lake Washington. People who look for evidence of past movement on faults are usually called paleoseismologists (from paleo-ancient and seismologist-one who studies earthquakes). Then consider that the Seattle Fault is a complex of faults with various branches that run at or just below the surface. Even places that are far from active faults are still at risk during a large Cascadia subduction zone earthquake. 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. Moving inland, the Seattle Fault is capable of a magnitude 7. That place is the Ocosta School. Why is Strange Sounds focusing so much on disaster preps? Move away from buildings, streetlights, and utility wires if you can. The San Andreas fault in California is a good example of a very active strike-slip fault. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). Radiocarbon ages of macrofossils constrain uplift timing to 2.83.2 ka. Save my name, email, and website in this browser for the next time I comment. The 1949 earthquake near Tacoma triggered a landslide near the Tacoma Narrows that caused a local tsunami. Bending of the fault and transpressional deformation began during the late middle Eocene and continues to the present. This scenario was modeled on the part of the SWIF from Woodinville to just west of Whidbey Island. Many faults have not been studied enough to know if they are active. All faults, regardless of size, can be dangerous if they rupture. A major southern Whidbey quake, on the other hand, could kill and injure many more, according to Murphy. 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. Contact Us, Whidbey Office On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. A 2014 map shows what we know about the age of faults in Washington. After a large earthquake it is common to have other large earthquakes for hours, days, and even weeks. Jump from 60 to 600 per week in just 5 years in Pahala, Is the Cascadia Subduction Zone about to blow? The fault probably originated during the early Eocene as a dextral strike-slip fault along the eastern side of a continental-margin rift. It can also make landslides that are much bigger than expected. Videos: Strong M6.0 earthquake rattles Mindanao in the Philippines, Dramatic earthquake increase in Hawaii! The Seattle fault last ruptured about 1,100 years ago in AD 900950. All Rights Reserved 2021, Site Disclaimer The southern Whidbey Island fault: An active structure in the Puget Lowland Washington, Geological Society of America Bulletin 1996;108;334-354. Additionally, because the continent moves up and over the ocean plate, large amounts of sea water are displaced and cause damaging tsunamis. 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. Each of the earthquakes listed on the bottom of the screen is capable of significant damage. South Whidbey Island Fault Zone. This category only includes cookies that ensures basic functionalities and security features of the website. Radiocarbon dating and other paleoseismic methods have also confirmed this date. Theyre FREE CLICK HERE to subscribe, EAR TO THE GROUND WITH DNR & COMMISSIONER FRANZ, Tree Link helps you answer questions about urbantrees. The buildings in this photo were built on soft materials that liquefied during the 1964 Niigata earthquake in Japan. The trenches exposed glacial deposits disrupted by faults and liquefaction features. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. This was a problem because no two locations would agree on the size of the same earthquake. 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. Theres an uneasy hush. Geologists at the Survey spend time mapping the geology of the state, looking for faults, folds, landslides, and different rock types. Roads, bridges, or ramps may have been damaged by the earthquake. Large earthquakes are less common but can cause significant damage to the things we count on in everyday life, such as buildings, roads, bridges, dams, and utilities. We just dont know when.. 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. 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. The most recent hit roughly 2,700 years ago. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. After large earthquakes there are usually many aftershock earthquakes. This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. Cover your head and neck with your arms to protect against falling debris. Everything points to one thing, Sherrod said, waving his hand across the inland sea. So the fault remained mostly a mystery until the 1990s. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. The last time was 1,000 years ago between 900 and 903 A.D., said Forson. Close to shore, this same wave could reach heights of 30100 feet or more. Paleoseismologists have found places that record many of these tsunami deposits. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. It devastated the coast of the Pacific Northwest and sent an orphan tsunami to Japan. For example, a M7 earthquake releases 32 times more energy than a M6 earthquake, and 1,000 times more than a M5 earthquake. . <> Liquefaction has caused significant damage during earthquakes in Washington. Notable earthquakes in bold happened in Washington. The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. A national credit rating service has improved its opinion of WhidbeyHealths financial future. 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. Sometimes Geologists can use the offset land surface to understand how much the fault moved during the earthquake. The buildings sank when ground shaking weakened the underlying sediments. This fault zone was originally named the Devils During the shaking liquefaction occurred, the sand lost its strength, and the car sunk. 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. But Forson says you also need to know what to do when the shaking happens. The French Onion trench exposed glaciolacustrine claystones, till, colluvial deposits, and Holocene soils. <>>> An official website of the United States government. The largest active fault that will affect Washington (and the whole Pacific Northwest) is the Cascadia subduction zone. Theres a must-see documentary film called Cascadia The Big One that exposes whats currently going on in this region of the Cascade volcanoes and the Pacific NorthWest. Photo from https://buildingfailures.files.wordpress.com/2014/02/tiltedbuilding.jpg. Every year Western. Small talk stops. The last large earthquake on the Cascadia subduction zone was in 1700. Hundreds could die, with thousands more injured. In places where there is little vegetation, different rock types and faults can be found with relative ease. Each type has different kinds of earthquakes. It usually also means that there are earthquakes (even small ones) on the fault. The Safe America Foundation suggests texting as a way of communication. Electricity, water, natural gas, and phones may not work. These cookies do not store any personal information. Landslides can be caused by strong ground shaking during an earthquake. Doorways do not provide protection from falling or flying objects and you may not be able to remain standing. The biggest one is called the South Whidbey Island fault, and it's thought to run from Victoria, B.C., through Woodinville and possibly beyond. In the Pacific Northwest we use the term shallow to talk about faults and earthquakes less than 18 miles deep. 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 Other types of seismic energy (S waves) also travel through the earth, but they move with a side-to-side (shearing) motion. 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 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. Most are too small to be felt or cause damage. These quakes are capable of magnitudes from 7 to over 9. When the landslide hit the water it may have created a tsunami. There are also many faults that have not been studied enough to know if they are active. The Cascadia subduction zone off the Washington and Oregon coast is capable of some of the largest earthquakes in the world. Power could be out for days. America is going to be punished just like the rest of the world. Small normal faults are found along the top of folds in eastern Washington in the Saddle Mountain graben. 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. 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. A baristas hand hovers over the bean grinder. While the intensity of this seismic event has now decreased, a big earthquake is overdue in the region. 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. (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. This photo shows a fence that was offset about 8.5 feet during the 1906 Great San Francisco Earthquake on the San Andreas fault. Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. 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. Graphic from IRIS. These faults and earthquakes occur in the continental crust of North America. The Cascadia subduction zone last ruptured over 300 years ago on January 26, 1700. This map shows areas of seismic risk from high (red) to low (grayish-green). The Seattle Fault is a zone of multiple shallow east-west thrust faults that cross the Puget Sound Lowland and through Seattle (in the U.S. state of Washington) in the vicinity of Interstate Highway 90.The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about . Though it was not directly related to Johnsons work, he asked a friend working for Mobil Oil to pass along the information. Official websites use .gov South Whidbey Island Fault (SWIF) M7.4 Earthquake Scenario Fire (Vegetation Condition Class) . #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. 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. 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. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. Later movement on this long-term active fault zone cut the volcano. Secure .gov websites use HTTPS In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. Once a fault is located, it is important to know if it is active. 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. A special type of shallow fault, called a subduction zone or megathrust, occurs where an oceanic plate moves beneath a continental plate. It may not be possible to find water, fuel, or food until services are restored days or even weeks after the event. The moment magnitude scale replaced the Richter scale in the late 1970s. Most of the populated areas of the state have a 4080% chance of having an earthquake in the next 50 years. Along the coast residents may have between 20 and 30 minutes to get to higher ground. These fault strands follow the valley edges and control the location of the Snoqualmie River along some portions of the valley. Watch the video below to learn how you can be ready for the next earthquake. But opting out of some of these cookies may affect your browsing experience. 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. Both studies suggested that the SWIF Do you live or work near an area that could have liquefaction? The height difference likely was caused by a 7.5 magnitude earthquake on the fault about 2,700 years ago, Sherrod said. Photo by Steve Palmer. Scientists have also dated large underwater landslides and turbidites that travel from the continental edge far out into the ocean basin. But it didnt. Excavations across several LiDAR scarps show evidence for multiple post-glacial folding and faulting event on faults with reverse oblique sense of slip. Knowing how often large earthquakes have happened in the past helps us to know how often they might occur in the future. 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. A magnitude 7.4 along the southern Whidbey fault would rattle 18 counties in Washington, according to a federal projection . % They didnt recognize the significance of what they found. Using the stratigraphic column from the Freeport quadrangle map, confirm that you can recognize . Third, the South Whidbey Island Fault running from northwest to southeast of the southern tip of the island. <> Even if the earthquake is too small to be felt by people, seismographs can detect it. Once the shaking has stopped, exit the building if it is safe to do so. Scientists dont know. We do not encourage people to evacuate in vehicles. Earthquakes cause damage by moving and shaking the ground, sometimes for several minutes. Earthquakes. The combination of all of these effects is what makes earthquakes such a powerful geologic hazard. His team wanted to find the rate of sea level rise along the shore. 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. The northwestern part of the fault zone forms the northeastern limit of the Port Townsend basin (Brocher and others, 2001 #4718). Camano Island, WA 98282, Mailing Address If they know theres data available that could help them in any way, they want to get it. North Anatolian Fault is currently locked, accumulating stresses which could be suddenly released anytime now like the Hayward Fault in California, Videos: New destructive M7.5 earthquake hits Turkey a few hours after largest quake in 100 years kills 1300. Audio; Before and After Images; Images; Slideshows; Stereograms; Videos; Webcams; . Ground shaking is a hazard near the epicenter of an earthquake and also in areas far from the earthquake where amplification occurs. 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. Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. This fundamental tool for earth scientists, maps show map units, faults and folds, cross sections, and other regional or local features, depending on map scale. These faults and earthquakes occur in oceanic crust as it is subducted beneath the continent. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. The last major earthquake was over 300 years ago. 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. For each increase in earthquake magnitude, there are about 10 times fewer earthquakes. It is mandatory to procure user consent prior to running these cookies on your website. Since about 1870 there have been about 15 large earthquakes (greater than M5) in the state. Disoriented drivers wonder whats wrong with their cars, then realize something much bigger is amiss. The Cascade block to the northeast is floored by diverse assemblages of pre-Tertiary rocks; the Coast Range block to the southwest is floored by lower Eocene marine basaltic rocks of the Crescent Formation. What about the localized tsunami risk? Be prepared and read more on DNR, USGS, King5, Strange Sounds and Steve Quayle. In much of Washington, dense vegetation covers the land and makes finding faults very difficult. Sherrods son has since completed graduate school in applied geosciences. Fault Activity Map of California. Like other faults, when enough stress builds up, the megathrust will rupture. of Earth and Space Sciences, Box 351310, Univ. But they didnt document it hardly at all.. It is capable of generating severe earthquakes that would impact the entire west coast. Photo by G.K. Gilbert, from the Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research Center. Never use a lighter or match near damaged areas. The age of the earthquake is learned by dating the organic material in these tsunami deposits. Image from the Pacific Geoscience Center of the Natural Resources of Canada. The affiliate sales will help us to continue the hard work we are putting in this website. Someone screams. Washington has dozens of active faults and fault zones.