Tacoma, WA. [195] The southwestern boundary of the SWCC, where it is believed to be in near vertical contact with the Eocene basalts of the Crescent Formation, forms a good part of the 90km (56 mile) long SHZ. Simply put, the basement rock on the west side of Puget Sound does not match the basement rock on the east side. Washington's fault lines tend to sweep east-west. This map shows areas of seismic risk from high (red) to low (grayish-green). 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a new perspective on seismic hazards in Washington using aeromagnetic data", "Constraints on surface deformation in the Seattle, WA, urban corridor from satellite radar interferometry time-series analysis", "Crustal Structure and Earthquake Hazards of the Subduction Zone in Southwestern British Columbia and Western Washington", "Late Mesozoic or Early Tertiary Melanges in the Western Cascades of Washington", "Seismotectonic map of the Puget Sound region, Washington", "Distribution of late Cenozoic volcanic vents in the Cascade Range: Volcanic arc segmentation and regional tectonic considerations", "Geologic map of the Wildcat Lake 7.5' quadrangle, Kitsap and Mason Counties, Washington", "Fault scarp detection beneath dense vegetation cover: airborne LIDAR mapping of the Seattle Fault Zone, Bainbridge Island, Washington State", 10.1130/1052-5173(2003)13<0004:HLTOTP>2.0.CO;2, "Structural variation along the Devil's Mountain fault zone, northwestern Washington", 10.1130/0091-7613(1980)8<15:SOTCVC>2.0.CO;2, "Fault number 572, Southern Whidbey Island Fault", "Active shortening of the Cascadia forearc and implications for seismic hazards of the Puget Lowland", "Active tectonics of the Seattle fault and central Puget Sound, Washington Implications for earthquake hazards", 10.1130/0016-7606(1999)111<1042:ATOTSF>2.3.CO;2, "Evidence for Late Holocene Earthquakes on the Utsalady Point Fault, Northern Puget Lowland, Washington", 10.1130/0091-7613(1994)022<0071:OAEOTS>2.3.CO;2, "The southern Whidbey Island fault An active structure in the Puget Lowland, Washington", 10.1130/0016-7606(1996)108<0334:TSWIFA>2.3.CO;2, "Late Holocene displacement on the Southern Whidbey Island fault zone, northern Puget lowland", "The Tahuya Lineament: Southwestern Extension of the Seattle Fault? 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. 09 Feb 2023 03:01:00 Just past them is the parallel Olympia Structure, which as a geophysical lineament has been traced to a point due east of Chehalis;[189] these would seem to be related somehow, but the nature of that relationship is not yet known. The Seattle Fault, a zone of east-west thrust faults under the Puget Sound and Seattle, last ruptured in a magnitude-7.0 to -7.5 earthquake about 1,100 years ago. [178] Alternately, the OS appears to coincide with a gravitational boundary in the upper crust that has been mapped striking southeast to The Dalles on the Columbia River,[179] where there is a swarm of similarly striking faults. Saint Helens and Mt. OLYMPIA, Wash. - A 9. 0 magnitude subduction earthquake off the Washington coast would generate a tsunami capable of submerging not only coastal areas but also most of the Puget Sound shoreline . Conjugate faults are secondary faults that branch off from opposite sides of a strike-slip fault at approximately the same angle. Tacoma's Gain is Seattle's Pain. Geologic Hazard Maps | WA - DNR These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault Calawah fault Barnes Creek [213] Seismicity sometimes occurs in zones, such as has been observed under Mercer Island, or from downtown Seattle towards Kirkland[214] but whether particular zones reflect undiscovered faults, or might be the source of damaging earthquakes, is generally unknown. It follows the Bainbridge Island ferry route east under Puget Sound and the route of Interstate 90 toward, and possibly beyond, the Cascade Mountains. These faults are: the Kopiah Fault (note the curious curve), Newaukum Fault, Coal Creek Fault, and three other unnamed faults. This map of Puget Sound shows the location of the methane plumes as yellow and white circles. https://en.wikipedia.org/w/index.php?title=Puget_Sound_faults&oldid=1132982136, Creative Commons Attribution-ShareAlike License 3.0, A great subduction earthquake, such as the. [54], It has been suggested that the SWIF might extend past its intersection with the RMFZ (with only peripheral strands turning to join the RMFZ) to cross the Cascades and eventually merge with or cross the OlympicWallowa Lineament;[55] a study of regional features suggests such a pattern. Puget Sound quake likely in Seattle Fault zone, geologists say - Phys.org This is an important observation because the Strawberry Point, Utsalady Point, Southern Whidbey Island, and various other unnamed faults lying between the DDMFZ and the OWL all of which converge at the western end of the DDMFZ seem to be intermediate versions of the DDMFZ.[34]. These faults are not quite aligned with the Olympia structure, striking N75W (285) rather than N45W (315). On the eastern side, where the SWCC is believed to be in contact with pre-Tertiary terranes accreted to the North American craton, matters are different. New tsunami maps show how water could reach Seattle, Everett, Tacoma WASHINGTON: Methane Bubbles Up From Seafloor Near Seattle [102] Or the Crescent margin may simply (and quietly) just run south-southeast under Seattle to the WRZ. [198], Does the SHZ extend north? Bubbles of methane rising from seafloor in Puget Sound - Phys.org Geographic boundaries of Puget Sound and the Salish Sea [5] The southern limit nearly matches the southern limit of the glaciation; possibly the seismicity reflects rebound of the upper crust after being stressed by the weight of the glacial ice. A Seattle Fault quake could be as large as M7.5,160 but less than M7.0 is more probable. [44] The significance of this whether the edge of the Crescent Formation (and implicitly of the Siletz terrane) turns southward (discussed below), or the metamorphic basement is supplanted here by other volcanic rock is not known. Analyze Instructions: Close. [120] However, the Saddle Mountain fault zone is not quite reciprocally aligned,[121] trending more northerly to where it encounters westeast trending faults (including the Hamma Hamma fault zone) that appear to be a westward extension of the Seattle Fault zone. Whether the faulting continues eastward is not yet determined. On the north is the HelenaHaystack mlange (HH mlange, purple in the diagram at right), on the south the Western and Eastern mlange belts (WEMB, blue). . Even before Washington became a state in 1889, Puget Sound beaches had been exploited as log dumps, farmed for shellfish, occupied as homesites and enjoyed for recreation. [207] North of the RMFZ it follows a topographical lineament that can be traced to Rockport (on Hwy. Do you live in a natural-disaster danger zone? Check this Seattle map American Seattle Cruise Reviews - Cruise Critic Puget Sound Tsunami Simulation - National Oceanic and Atmospheric How the CRBF might run north of Seattle (specifically, north of the OWL, which Seattle straddles) is unknown, and even questioned, as there is no direct evidence of such a fault. The true length of the UPF is likely twice as long, as it forms the southern margin of an aeromagnetic high that extends another 25km to the southeast. (Links with more information on various hazards can be found at Seattle Fault.). to the north, past Lummi Island is contrary to the prevailing consensus that the DMF is not offset. [140] Recent geophysical modeling suggests that the Dewatto lineament is the expression of a blind (concealed), low-angle, east-dipping thrust fault, named the Dewatto fault. [216], An Everett Fault, running east-northeast along the bluffs between Mukilteo and Everett that is, east of the SWIF and at the southern edge of the Everett Basin has been claimed, but this does not appear to have been corroborated.[217]. Although the largely unstudied White River Fault (WRF) appears to lie just outside the Puget Lowland, it may actually connect under the Muckleshoot Basin to the East Passage Zone and the Tacoma Fault (map). [38] These earthquakes probably caused tsunamis, and several nearby locations have evidence of tsunamis not correlated with other known quakes. (2001),[111] relying on seismic tomography data from the "Seismic Hazards Investigation in Puget Sound" (SHIPS) experiment, retains the thrusting slab and master ramp concepts, but interprets the Tacoma fault as a reverse fault (or back thrust) that dips north towards the south dipping Seattle fault (see diagram); as a result the Seattle Uplift is being popped up like a horst. The WRZ and SHZ are associated with the southern Washington Cascades conductor (SWCC), a formation of enhanced electrical conductivity[194] lying roughly between Riffe Lake and Mounts St. Helens, Adams, and Rainier, with a lobe extending north (outlined in yellow, right). TTY Relay 711. ), and headed for the definitely active Saint Helens Zone; this appears to be a large-scale structure. [87], Rattlesnake Mountain is a prominent NNW trending ridge just west of North Bend (about 25 miles east of Seattle). [141] (Originally named the Tahuya Fault. [19] These terranes were covered by the basalts of the Crescent Formation (part of Siletzia). It may also be the original location of the DarringtonDevils Mountain Fault (the dashed line "X" at the top of the following map). These lineaments have been associated with possible zones of faulting in the crust and subducting plate.[212]. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). The Devils Mountain Fault separates two similar but distinctive ensembles of Mesozoic (pre-Tertiary, before the dinosaurs died) or older rock. A magnitude 7.1 earthquake in the Tacoma Fault Zone A plausible scenario for the southern Puget Sound region, Washington May 18, 2010 Citation Information. Though the Olympia Structure (a suspected fault) runs towards the SHZ, and delineates the northern edge of an exposed section of the Crescent Formation, it appears to be an upper crustal fold, part of a pattern of folding that extends southeast to cross the Columbia River near The Dalles, and unrelated to the mid and lower crustal SHZ. Some upper-crustal formations (such as the Western and Eastern Melange Belts, see, There is a general north or northeast directed compression within the Lowland causing folds, which eventually break to become, This page was last edited on 11 January 2023, at 17:28. Other similar lineaments (such as from Astoria to Glacier Peak) align with various topographical features and changes in fault orientation. But their significance to the Puget Sound area is unknown. A Massive Earthquake Is Coming to CascadiaAnd It Can't Be Stopped The Seattle uplift, and possibly the Black Hills uplift, consist of Crescent Formation basalt that was exposed when it was forced up a ramp of some kind. These bends are located where they intercept a "subtle geological structure"[202] of "possible fundamental importance",[203] a NNE striking zone (line "A" on the map) of various faults (including the Tokul Creek Fault NNE of Snoqualmie) and early-Miocene (about 24 Ma) volcanic vents and intrusive bodies (plutons and batholiths) extending from Portland to Glacier Peak;[204] it also marks the change in regional fault orientation noted above. 112 earthquakes in the past 365 days. If so, this would be a major fault system (over 185km long), connecting the Puget Lowland with the Yakima Fold Belt on the other side of the Cascades, with possible implications for both the OlympicWallowa Lineament (which it parallels) and geological structure south of the OWL. After all, Olympia, which is the closest of the cities to the megathrust fault, is estimated to experience the least severe shaking; at the same time, many cities on the east side of the Puget Sound further away from the fault experience much stronger shaking. What makes the DotySalzer Fault (and the short Chehalis Fault striking due east from Chehalis) stand out from the many other faults south of Tacoma is its eastwest strike; the significance of this is not known. Other faults to the south and southeast the Frigid Creek Fault and (to the west) Canyon River Fault suggest an extended zone of faulting at least 45km long. Those Hollywood depictions of a. (A tsunami generated by a quake on the offshore Cascadia Subduction Zone would be . A Lofall Fault has been reported on the basis of marine seismic reflection surveying,[216] but has not been confirmed by trenching. Very little is known about the structure of the deep crust (below about 30km or 19 miles), though this and other seismic tomography studies (such as Ramachandran 2001) provide tantalizing glimpses. Earthquakes and Faults | WA - DNR [122] This trend extends further north where the Pleasant Harbor lineament appears to terminate other westward extensions of the SFZ. [104] Although there is no direct evidence for any major north-striking faults under Seattle, this prospect appears to be endorsed by the geological community.[105]. Get directions. A Puget Sound Fault running down the center of Puget Sound (and Vashon Island) was once proposed,[220] but seems to have not been accepted by the geological community. Although Washington State's Puget Sound has been shaken every few decades, damage in the region's largest cities, including Seattle, Tacoma and Olympia, has only ever been modest. PNSN staff will continue to develop this section of the web site but to find more good information now, visit these resources: It is not notably seismogenic. Could a Tsunami Hit Puget Sound? - Washington Sea Grant A 2001 study[148] using high-resolution seismic tomography questioned its existence. [215] [95], (Rattlesnake Mountain Fault Zone not included in QFFDB. Other similar rock has been found at the Rimrock Lake Inlier (bottom of diagram), in the San Juan Islands, and in the Pacific Coast Complex along the West Coast Fault on the west side of Vancouver Island. [66] This is located on a topographical lineament that aligns with Mount Vernon to the north, and, to the south, the city of Granite Falls and Lake Chaplain (just north of Sultan). This forms a pocket or trough what one local geologist calls the "big hole between the mountains"[17] between the Cascades on the east and the Olympic Mountains and Willapa Hills on the west. Earthquakes occur nearly every day in Washington. About 1,100 years ago, a major earthquake rocked Puget Sound, suddenly shooting what is now Restoration Point on Bainbridge Island up about 23 feet while Seattle 's West Point sunk more than. These faults also form the north and south boundaries of uplifted pre-Tertiary rock, suggesting that the faults come together at a lower level, much like one model of the Seattle and Tacoma faults, but at a smaller scale. The map is from a 2007 report (click here to download) on seismic design categories in Washington. 6) Click "Plot" Draw. Washington's faults: Where the Earth moves the Seattle area Harold Tobin, . Over 7,000 people are dead after a magnitude 7.8 earthquake shook southern Turkey, near the Turkish-Syrian border. Please follow the steps below: . And like the SCF, strike-slip motion died out between 44 and 41 MA (due to plutonic intrusions). The San Juan Island and Leach River faults crossing the southern end of Vancouver Island are significant and undoubtedly connected with the DarringtonDevils Mountain and Southern Whidbey Island faults, and certainly of particular interest to the residents of Victoria, B.C. Following a mega quake on the Cascadia fault, simulations show that the tiny town of La Push would get hit first by a tsunami, 10 minutes after shaking started. [68] Both of these faults (and some others) appear to terminate against the left-lateral Sultan River Fault at the western margin of the NNE-striking Cherry Creek Fault Zone (CCFZ; see next section). In the map above these are represented by the pair of dotted lines at the lower right. [185] The prospect of a major earthquake on the Doty Fault poses a serious hazard to the entire Puget Sound region as it threatens vital economic lifelines: At Chehalis there is but a single freeway (Interstate 5) and a single rail line connecting the Puget Sound region with the rest of the west coast; the only alternate routes are very lengthy.[186]. fault Which of the following statements best describes elastic-rebound theory? Harold Tobin, a researcher at the University of Washington and director of the Pacific Northwest Seismic Network, says the fault line that caused this disaster is similar to the faults under Puget Sound. [199] It has been speculated that the SHZ might extend under the Kitsap Peninsula (central Puget Sound), possibly involved with a section of the subducting Juan de Fuca plate that is suspected of being stuck. Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc CC BY 4.0 Authors: H. Paul Johnson University of Washington Seattle S. G. Merle National Oceanic and. Also intersecting at Mount St. Helens is a NE (045) trending line (red) of Pleistocene (about 4 Ma) plug domes and a topographic lineament (followed in part by Highway 12). Clearance, service lines and meter locations. [56] But detailed mapping just past the intersection shows only a complex and confused pattern of faulting, with no indication that there is, or is not, through-going faulting. 14 earthquakes in the past 30 days. Here the main strand on the western edge merges with the Sultan River Fault under the Sultan River. [119] Several studies show that the southernmost strand of the SF, once past Green Mountain, turns southwest, towards the Saddle Mountain and Frigid Creek faults. King County Emergency News. [145] This is conformable with some regional tectonic interpretations[146] that put a major terrane boundary between the Olympics and the Puget Lowland, and imply a connection (either via the Discovery Bay Fault, or closer to Port Townsend) to the various faults in the Strait of Juan de Fuca. [127], The Tacoma Fault (at right, and also between lines C and D on the Uplift and basin map, above) just north of the city of Tacoma, Washington has been described as "one of the most striking geophysical anomalies in the Puget Lowland". South of the OWL a definite eastern boundary has not been found, with some indications it is indefinite. For information about the Energize Eastside project, . Despite not having active plate tectonics, the eastern United States still experiences earthquakes. [130] This is likely not coincidental, as it appears that the Tacoma and Seattle faults converge at depth (see diagram above) in a way that northsouth compression tends to force the Seattle Uplift up, resulting in dip-slip movement on both fault zones. A marine seismic reflection study[177] found evidence of faulting at the mouth of Budd Inlet, just north of the Olympia structure, and aligning with faint lineaments seen in the lidar imagery. While these models vary in some details, both indicate that the Seattle Fault itself is capable of a magnitude 7.5 earthquake. Earthquake Hazard Maps | Sound Seismic They run . [79] It is deemed a "major active or potentially active" structure. Toll Free 1-800-523-5044. Doubts on the connectivity of these faults led to abandonment of this name in 1986[65] when Cheney mapped the Mount Vernon fault (MVF) from near Sultan northwest past Lummi Island (west side of Bellingham Bay, visible at the top of the map), crossing the Devils Mountain Fault (DMF, part of the DarringtonDevils Mountain Fault Zone) near Mount Vernon. $30 to $33 Hourly. Seattle Fault - Wikipedia 1 - 10 of 83 American Seattle Cruise Reviews. Posted: 12 days ago. There are other tsunami scenarios that are not accounted for in these maps, such as tsunamis caused by . [188] In the acute angle between these is located the minor Lincoln Creek uplift, the Doty Hills, and an impressive chunk of uplifted Crescent basalt (reddish area at west edge of the map). The Bellingham BayChaplain fault zone was first mapped by Cheney in 1976 as running from near Chaplain Lake (north of Sultan) NNW past Bellingham Bay. [89] The northern end of the mountain falls off where it crosses the eastern end of the Seattle Fault, which in turn terminates at the RMFZ; Rattlesnake Mountain forms the eastern edge of the Seattle Uplift. And since those models for the Seattle Fault were published, there've actually been many more Puget Sound faults discovered. In the previous study seismicity, surface geology, and geophysical data were modeled in order to examine the fault structuring of the upper crust. (E.g., the Olympia Fault is aligned with and appears to be the northernmost member of a set of faults between Olympia and Chehalis that may extend to the Columbia River, and there has been a suggestion that the Tacoma Fault may connect with the White RiverNaches River fault on the east side of the Cascades.[24]).
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