southern whidbey island fault map

@\;L;=}%FC*l $@ 4x: 888O~xrsxx'/*rGRF\gI%~x(G-^-hjjq kx/V ou0hyegy0;ei`Tx&ilZ )TmZ$vb,`bQm|DR5x/ 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. If you are already planning your Christmas gifts, please buy with us on Amazon. This averages to ~660 to 525 years between events, but there is a lot of variation. 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. In the area of North Bend, the fault zone is 4 miles wide and consists of a series of parallel faults. The threat to Puget Sound from a quake along the Cascadia Subduction Zone, off the coast of Washington, Oregon and California, is well documented. They conclude the observed features have a glaciotectonic origin and are not seimotectonic. 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. 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 What are the most dangerous fault lines for Seattle? Close to shore, this same wave could reach heights of 30100 feet or more. Evacuate to higher ground if you are near a large body of water. Scientists have been trying to understand how often earthquakes happen for over 100 years. Most are too small to be felt or cause damage. Please visit our Geologic Information Portal and Geologic Hazard Maps page for the most up-to-date listing of all of our hazard maps. Map Releases; Topographic (Topo) Maps; Volcanic Maps; All Maps; Multimedia Gallery. This movement created a tsunami in Puget Sound and triggered a large landslide into Lake Washington. We use the term deep to talk about faults and earthquakes deeper than about 18 miles. Within this rich oral history there are many references to events like earthquakes and tsunamis. East of Puget Sound, the SWIF makes landfall between the cities of Seattle and Everett but is concealed . For example, a M7 earthquake releases 32 times more energy than a M6 earthquake, and 1,000 times more than a M5 earthquake. ?7) and represents a potential seismic hazard to residents of the Puget Lowland. Scientists are not sure how far east it goes. USA Earthquake Hazard Map. 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. endobj Most damage and loss of life in earthquakes is a result of ground shaking. A thrust fault is a special kind of reverse fault that has a shallow dip. Check out the liquefaction susceptibility and NEHRP site class maps on the Geologic Hazard Maps page. If folding on the Little Bear Creek lineament resulted in one or two of unconformities, the poorly constrained timing of the earthquakes is younger than 12,000 yr BP and older than about 2,850 cal yr BP. Even if the earthquake is too small to be felt by people, seismographs can detect it. 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. Tsunamis and seiches are destructive waves which can be triggered by certain types of large earthquakes. What about the localized tsunami risk? 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. Everything points to one thing, Sherrod said, waving his hand across the inland sea. Others, like the Seattle fault and southern Whidbey Island fault zone, cross under major cities and pose a significant hazard. If they know theres data available that could help them in any way, they want to get it. The coast is now the home of one of the states largest network of warning sirens called All Hazard Alert Broadcast (AHABs). The Southern Whidbay Island Fault represents another major earthquake threat for Seattle and its residents. <>>> of Earth and Space Sciences, Box 351310, Univ. Tap/click on "gear icon" for options and settings. 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. His team wanted to find the rate of sea level rise along the shore. 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. Photo by Steve Palmer. Know what to expect. A normal fault occurs when two blocks are pulled away from each other. 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. Years ago, Howard Gower and James Yount came to the Puget lowlands to study earthquake risks and stumbled on what appeared to be a fault in Island and Snohomish counties. The Safe America Foundation suggests texting as a way of communication. These types of faults are common, but usually small. The best thing you can do is to become prepared. The more you know what to expect, the better prepared you will be to help yourself, your family, and others around you. After the shaking stopped the sand regained its strength. This uplift creates a very broad wave called a tsunami. It is capable of generating severe earthquakes that would impact the entire west coast. Map by And while scientists keep digging for more information and more situational awareness of what we face, the other problem is human. In the Puget Sound region, it takes a trained eye to recognize rocky outcrops and subtly raised ground as evidence of a fault. The South Whidbey Island Fault and Darrington Devil's Mountain Fault bound the Everett Basin. Johnson, on a whim, acquired the data that would prove its existence beyond a doubt. 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 . Higher risk areas are in orange and lower risk areas are in green. A community meeting about a shelter at the Harbor Inn may have yielded more questions than answers. Once a fault is located, it is important to know if it is active. Another piece can be seen under the elevated lanes of northbound Interstate 5 in South Seattle not far from the Rainier brewery. Sherrod shrugged his shoulders. 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. 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). 2 0 obj A small quake was registered in the Coupeville area just this summer. One of the most important new technologies for finding faults (and landslides too) is called lidar. Most faults in Washington are a mix of a strike-slip fault and a thrust or reverse fault. Coupeville, WA 98239, Camano Office An earthquake occurs when rock inside the Earth moves or breaks. If you are in bed: STAY there and COVER your head and neck with a pillow. Large earthquakes, like those from the Cascadia subduction zone on January 26, 1700, often create tsunamis. This map shows areas of seismic risk from high (red) to low (grayish-green). Small talk stops. Within minutes, he spotted something groundbreaking. A national credit rating service has improved its opinion of WhidbeyHealths financial future. Because they rupture at such great depth, their seismic energy is distributed over a large area. The SWIF has been assessed by the USGS as capable of generating the largest crustal earthquake in Puget Sound. Landslides can be caused by strong ground shaking during an earthquake. During site visits in 2005, Sherrods team found evidence of four SWIF earthquakes in the past 30,000 years. These faults and earthquakes usually occur at great depth (tens to hundreds of miles). The fault has at least three almost parallel strands within a 4- to 7-mile-wide band, stretching eastward from Vancouver Island. 1 0 obj Stop as quickly as safety permits and stay in the vehicle. Tsunamis and seiches can also be triggered by large slides, both on land and underwater. 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. Electricity, water, natural gas, and phones may not work. (Andy Bronson / The Herald). For some active faults, such as the Seattle fault or Cascadia subduction zone, we can also learn how often large earthquakes have happened in the past. Photo from, This image shows the how the 1700 AD tsunami from the Pacific Northwest crossed the Pacific Ocean. Learning earthquake faults around where we live is a first good way to prepare the next devastating earthquake. On Dec. 15th, a small swarm even hit near Bremerton, a few miles away from downtown. View Earthquake Map Faults Interactive fault map and comprehensive geologically based information on known or suspected active faults and folds in the United States. The Cascadia subduction zone off the Washington and Oregon coast is capable of some of the largest earthquakes in the world. In the month after the main earthquake there were about 60 M7 and M6 earthquakes. The southern Whidbey Island fault, and several others, were exposed for the first time from a camouflage of forest, ocean and glacial sediment. Scientists dont know. Like other faults, when enough stress builds up, the megathrust will rupture. Liquefaction is when wet soil or sediment loses strength because it is being shaken during an earthquake. Johnson and others . Roads, bridges, or ramps may have been damaged by the earthquake. Larger crustal faults, such as the Seattle fault and southern Whidbey Island fault zone, can produce earthquakes up to magnitude 7.5. Recent geologic mapping by Washington State Department of Natural Resources (DNR) geologists reveals that this major fault zone extends through the Snoqualmie River valley in the vicinity of Carnation, Fall City, and North Bend. It is a qualitative scale that ranges from IXI (1-11) and measures the amount of damage caused by an event. With Medical Martial Law imposed in Washington state. And being ready means being able to support yourself, your loved ones, your neighborhood for 2 weeks. A baristas hand hovers over the bean grinder. This is a hypothetical scenario created by Mark Murphy of the Snohomish County Department of Emergency Management. These faults and earthquakes occur in the continental crust of North America. Power could be out for days. Large and damaging earthquakes are inevitable in Washington, but no one knows exactly when they will happen. The fault, not so much. Sometimes Geologists can use the offset land surface to understand how much the fault moved during the earthquake. This earthquake is along the southern Whidbey Island fault, a less-known, less-studied subterranean boundary. When earthquakes occur on faults that reach the Earths surface, the ground may rupture. In this sense, the shaking of the ground is the sound of rocks breaking and moving deep within the Earth. Faults can also be grouped based on what part of the crust they occur in. There are also tsunami evacuation signs on the highways. Since the last ice age, the southern Whidbey Island fault zone has probably spawned several highly destructive shallow earthquakes. For earthquakes that occurred before seismographs were invented, the Mercalli Intensity scale was used to make maps of damage and determine the size and location of an earthquake.