[192] Indeed, it is mainly by their seismicity that these faults are known and have been located, neither showing any surface faulting. [59] Another study identified an unusually broad band of scarps passing between Bothell and Snohomish, with several scarps in the vicinity of King County's controversial Brightwater regional sewage treatment plant showing at least four and possibly nine events on the SWIF in the last 16,400 years. If entirely analogous, then "roof duplex" might also apply, and the Olympia Fault would be a reverse fault similar to the Tacoma Fault. [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. This is supported by geologically recent scarps and other signs of active faulting on the Saddle Mountain faults, and also discovery of a geophysical lineament running through Pleasant Harbor (south of Brinnon) that appears to truncate strands of the Seattle Fault. [Paper No. external structure, lines, and riggings; stand deck watches, such as helmsman and lookout underway; stand pier sentry, fire security, anchor, and . The Devils Mountain Fault (DMF) runs about 125km (75 miles) from the town of Darrington in the Cascade foothills due west to the northern tip of Whidbey Island, and on towards Victoria, British Columbia, where the DMF is believed to join the Leech River fault system at the southern end of Vancouver Island. Just four miles (6km) south the city of Oak Harbor straddles several stands of the Utsalady Point Fault (UPF) as they head roughly east-southeast towards Utsalady Point at the north end of Camano Island. There are other tsunami scenarios that are not accounted for in these maps, such as tsunamis caused by . Ongoing mapping is revealing more faults. PNSN Recent Events | Pacific Northwest Seismic Network The Doty Fault appears to terminate against, or possibly merge with, the Salzer Creek Fault at Chehalis; the Salzer Creek Fault is traced another seven miles east of Chehalis. [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]. Aeromagnetic anomaly maps (USGS OFR 99-514). One problem with this is that the parts of the SWIF east of Puget Sound do not show the velocity contrasts that would indicate contrasting rock types. The Little River Fault (see the QFFDB, Fault 556) is representative of an extensive zone of faults along the north side of the Olympic Peninsula and in the Strait of Juan de Fuca (likely connected with the fault systems at the south end of Vancouver Island, see fault database map), but these lie west of the crustal blocks that underlie the Puget Lowland, and again their possible impact on the Puget Sound region is unknown. Deep quakes are the most common large earthquakes that occur in the Puget Sound region. Earthquakes occur nearly every day in Washington. Report: Earthquake could produce tsunami waves that would hit Seattle The Puget Sound region is not just potentially seismic, it is actively seismic. On the other hand, the contrasting character of the east-striking and southeast-striking segments is unsettling, and the change of direction somewhat difficult to reconcile with the observed fault traces. Earthquakes and Faults | WA - DNR [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). [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. Recent EQ List For the following reviews the primary source of information is the U.S. Geological Survey's Quaternary fault and fold database (QFFDB), which includes details of discovery, a technical description, and bibliography for each fault; a specific link is provided (where available) at the end of each section. NW-striking black lines are right-lateral bedrock faults thought to be subsidiary to Dar- rington-Devils Mountain fault zone (Dragovich and DeOme, 2006). That wave is quite severe, quite high. If, as this model suggests, the various faults are interconnected within the thrust sheet, there is a possibility that one earthquake could trigger others. [131], The Tacoma Fault was first identified by Gower, Yount & Crosson (1985) as a gravitational anomaly ("structure K") running east across the northern tip of Case and Carr Inlets, then southeast under Commencement Bay and towards the town of Puyallup. South of the OWL a definite eastern boundary has not been found, with some indications it is indefinite. Curiously, the extension of line "B" north of the OWL is approximately the eastern limit of Puget Sound seismicity, the rest of southwestern Washington and the North Cascades being relatively aseismic (see the seismicity map, above). [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. They are also on-strike with a swarm of faults on the Columbia River, bracketing The Dalles. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. American Spirit Cruise Reviews - Cruise Critic It aligns with the West Coast fault and Queen Charlotte Fault system of strike-slip fault zones (similar to the San Andreas Fault in California) on the west side of Vancouver Island, but does not itself show any significant or through-going strike-slip movement. Cheney also mapped the Lake Chaplain Fault, parallel and just east of the MVF, from Lake Chaplain to Granite Falls. One of these faults, the Sequim Fault Zone (striking east from the town of Sequim), crosses Discovery Bay (and various possible extensions of the Hood Canal Fault) and bounds the Port Ludlow Uplift ("uplift of unknown origin" on the map); it appears to extend to the Southern Whidbey Island Fault. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. Puget Sound Lidar Consortium Finding faults scarp(n). 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. [181] What is unknown is whether this was due to a great subduction earthquake, to the noted earthquake on the Seattle Fault about that time, or to an earthquake on a local fault (e.g., the Olympia structure); there is some evidence that there were two earthquakes over a short time period. [79] It is deemed a "major active or potentially active" structure. This follows the front of the Rosedale monocline, a gently southwest-tilting formation that forms the bluffs on which Tacoma is built. Energy builds up as elastic strain in rocks. Read More. There is a general pattern where most of these faults partition a series of basins and uplifts, each about 20km wide. According to the preeminent model, the "Puget Lowland thrust sheet hypothesis",[26] these faults, etc., occur within a sheet of crust about 14 to 20km deep that has separated from and is being thrust over deeper crustal blocks. Five Puget Sound cities likely to feel strong shaking in a megaquake Of great interest here is that both the northern lobe of the SWCC and the Carbon River anticline are aligned towards Tiger Mountain (an uplifted block of the Puget Group of sedimentary and volcanic deposits typical of the Puget Lowland) and the adjacent Raging River anticline (see map). Relatively shallow crustal earthquakes, generally less than 25km (16 miles) deep, caused by stresses and faulting in the near-surface crustal structures. (A) Map of the Seattle fault zone (SFZ) in the central Puget Sound The Frigid Creek fault seems more directly aligned with this southwestward extension of the Seattle Fault, but such a connection seems to be as yet unremarked by geologists. The Canyon River Fault is believed to have caused a similar-sized earthquake less than 2,000 years ago;[167] this is a particular hazard to the Wynoochee Dam (to the west). [183] While the towns of Centralia and Chehalis in rural Lewis County may seem distant (about 25 miles) from Puget Sound, this is still part of the Puget Lowland, and these faults, the local geology, and the underlying tectonic basement seem to be connected with that immediately adjacent to Puget Sound. The EPZ is active, being the locale of the 1995 M 5 Point Robinson earthquake.[136]. It is not known to be seismic indeed, there is very little seismicity south of the Tacoma Basin as far as Chehalis[169] and not even conclusively established to be a fault. The SE striking Scammon Creek Fault seems to be terminated by the Salzer Creek Fault (the exact relationship is not clear), with the latter continuing east for another seven miles. Nurse Information Line at VA Puget Sound health care, 800-329-8387 x4. [162] Trench studies indicate major earthquakes (in the range of M 6. to 7.8) on the Saddle Mountain faults [163] at nearly the same time (give or take a century) as the great quake on the Seattle Fault about 1100 years ago (900930 AD). (Links with more information on various hazards can be found at Seattle Fault.). In the map above these are represented by the pair of dotted lines at the lower right. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). PSE | Energize Eastside Improvements Project [153] For these reasons this is now a questioned fault, and is indicated on the map as a dashed line. [21] The OWL appears to be a deep-seated structure over which the shallower crust of the Puget Lowland is being pushed, but this remains speculative. 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. 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. Prior to 2000, prominent aeromagnetic anomalies strongly suggested that the fault zone continued southeast, perhaps as far as the town of Duvall, but this was uncertain as the SWIF is largely concealed, and the faint surface traces generally obliterated by urban development. [70] Although the intervening section has not been mapped, geologists believe the GFFZ connects with the McMurray FZ to the north, and forms the eastern boundary of the Everett Basin. 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. Study of surface deformation suggests possible unmapped faults near Federal Way, running between Sumner and Steilacoom, and south of Renton.[223]. Tsunami waves would reach Seattle within minutes after earthquake . Plot. The maps show slightly lower . Movement on the southern segment of the DDMFZ that converges with the SCF the Darrington Fault was, as on the SCF itself, right-lateral. It is uncertain how these faults relate to the structure, and whether they are deep-seated faults, or fractures due to bending of the shallow crust. The University of Puget Sound's Facilities Services Department is hiring an Electrician responsible for the inspection, installation, modification, maintenance and repair of the electrical systems across Puget Sound's beautiful residential campus community located . Over 7,000 people are dead after a magnitude 7.8 earthquake shook southern Turkey, near the Turkish-Syrian border. 48), along the edge of a formation known as the Southern Washington Cascades Conductor. At the edge of this older rock is the Rogers Belt, a geologically interesting zone running from the area of Sultan (due east of Everett) to Mount Vernon (just north of the bend in the Devils Mountain Fault). The Pacific Northwest Seismic Network (PNSN) reported at least three earthquakes within the past few days. Active faults and earthquakes in Washington state Seismic Scenario Catalog NEHRP site class and liquefaction susceptibility Seismic design categories Hazardous Minerals Lahar Hazards Landslides and landforms Inactive and abandoned mines Contact Us Susan Schnur Editor-in-Chief 360-701-6122 DNR is led by Commissioner of Public Lands Hilary Franz The fault type is subducting. [154] In this view Hood Canal is only a syncline (dip) between the Olympic Mountains and the Puget Lowland, and such faults as have been found there are local and discontinuous, ancillary to the main zone of faulting to the west. [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. It has been speculated that the OS might connect with the seismically active Saint Helens Zone (discussed below), which would imply that the OS is both locked and being stressed, raising the possibility of a major earthquake. [191] How they might be connected is unknown. Study: Tsunami from Cascadia mega-quake would submerge Puget Sound [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). Contact Us | VA Puget Sound Health Care | Veterans Affairs Yet the SHZ and WRZ may be integral to the regional geology of Puget Sound, possibly revealing some deep and significant facets, and may also present significant seismic hazard. At Darrington it is seen to connect with the Darrington Fault, which runs nearly south 110km to converge with the Straight Creek Fault (SCF), and then to turn near Easton to align with the OlympicWallowa Lineament; together these are known as the DarringtonDevils Mountain Fault Zone (DDMFZ). [8] As of 1985 only the Saddle Mountain Faults had been shown to have Holocene activity (since the last ice age, about 12,000 years ago). A UW researcher says the fault line that caused earthquake that shook southern Turkey near the Turkish-Syrian border this week and killed more than 7,000 people is similar to the faults under Puget Sound. Though a 2012 study[149] interpreted a different variety of tomographic data as showing the Hood Canal fault, other mapping has "found no convincing evidence for the existence of this fault",[150] considers it doubtful,[151] depicted it "with low level of confidence",[152] or omits it entirely. PNSN staff will continue to develop this section of the web site but to find more good information now, visit these resources: Geologic Map. An informal consortium of regional agencies has coordinated LIDAR mapping of much of the central Puget Lowland, which has led to discovery of numerous fault scarps which are then investigated by trenching (paleoseismology). [102] Or the Crescent margin may simply (and quietly) just run south-southeast under Seattle to the WRZ. One study of seismic vulnerability of bridges in the Seattle Tacoma area[4] estimated that an M 7 earthquake on the Seattle or Tacoma faults would cause nearly as much damage as a M 9 subduction earthquake. These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) The QFFDB, citing lack of consensus, ignores the eastern part. [37] Trenching on the UPF (at a scarp identified by LIDAR) shows at least one and probably two Holocene earthquakes of magnitude 6.7 or more, the most recent one between AD 1550 to 1850, and possibly triggered by the 1700 Cascadia earthquake. A Massive Earthquake Is Coming to CascadiaAnd It Can't Be Stopped Yet the former is only the first of at least six more parallel southeast striking faults, which do cross the Salzer Creek Fault. It does bound the north side of the Chehalis basin, but the south boundary of the Black Hills Uplift is more properly the southeast striking Scammon Creek Fault that converges with the DotySalzer Creek Fault just north of Chehalis. This formation, up to 15km thick, is largely buried (from one to ten kilometers deep), and known mainly by magnetotellurics and other geophysical methods. [91] The relationship between these two fault zones is not entirely clear. Can be formed by differential erosion of adjacent hard and soft rock; by localized erosion, for example at the edge of a river terrace; by movement of a landslide; or by a shallow earthquake that is large enough to break the Earth's surface. The energy of the somewhat smaller Benioff earthquakes is likewise diluted over a relatively large area. - Read More Expert Puts Turkey, Syria Quake into Perspective | FOX 13 Geologic map of southwestern Washington (GM-34). Interpretation of the eastern part of the Tacoma Fault is not entirely settled. [164] Such quakes pose a serious threat to the City of Tacoma's dams at Lake Cushman,[165] located in the fault zone,[166] and to everyone downstream on the Skokomish River. [49] Yet it is also notable that "most seismicity in the northern Puget Sound occurs along and southwest of the southern Whidbey Island fault at typical depths of 1527 km within the lower part of the Crescent Formation. It is of interest here because the various strands of the Seattle Fault change orientation where they appear to cross the OWL,[20] and various other features, such as the Rosedale monocline and Olympia structure, and a great many local topographical features, have parallel alignments. The Puget Sound faults under the heavily populated Puget Sound region (Puget Lowland) of Washington state form a regional complex of interrelated seismogenic (earthquake-causing) geologic faults. "Puget Sound and related inland marine waters, including all salt waters of the state of Washington inside the international boundary line between Washington and British Columbia, and lying east of the junction of the Pacific Ocean and the Strait of Juan de Fuca, and the rivers and streams draining to Puget Sound as mapped by water resource . Observing these topographical features, some parallel gravity gradients, and a "very active zone of minor seismicity", William Rogers inferred in 1970 a "fault or other major structural feature".[64]. The question of where on Puget Sound the line would ultimately end was intentionally left open, and the region's fledgling cities began competing furiously for the good fortune of a major railroad terminus. 4 earthquakes in the past 30 days. Scientists Search for New Faults in Puget Sound Although the southwest striking Canyon River Fault is not seen to directly connect with the Saddle Mountain faults, they are in general alignment, and both occur in a similar context of Miocene faulting (where Crescent Formation strata has been uplifted by the Olympics) and a linear aeromagnetic anomaly. Could a Tsunami Hit Puget Sound? - Washington Sea Grant This seems geologically reasonable, as both the SWIF and RMFZ appear to be the contact between Tertiary Crescent Formation basement of Puget Sound on the west and the older Mesozoic (pre-Tertiary) mlange belt basement rocks under the Cascades on the east.[110]. A magnitude 7.1 earthquake in the Tacoma Fault Zone A - USGS The Woods Lake Fault, running past Lake Chaplain, corresponds closest to the mapped position of the southern end of Cheney's Mount Vernon Fault. It has been suggested that a corresponding change in the character of the SWIF may reflect a change in the direction of regional crustal strain. It appears the entire DDMFZ and Leech River fault system was pushed onto the early continental margin from an original alignment along the OWL. For information about the Energize Eastside project, . This may explain why the Seattle and Tacoma faults seem to have ruptured at nearly the same time.[127]. Thick glacial and other deposits, heavy vegetation, urban development, and a topography of sharp relief and rapid erosion obscures the surface expression of faults in this region, and has hindered their discovery. This boundary would be the contact where northward movement of the basement rock of the Puget Lowland against the Olympic Peninsula is accommodated; it would be expected to be a significant seismological zone. [138] It arises from the contrast between the denser and more magnetic basalt of the Crescent Formation that has been uplifted to the east, and the glacial sediments that have filled the Dewatto basin to the west. A Tsunami Hits Puget Sound: New Simulation Shows How It Unfolds Housing: The Puget Sound had the largest increase in population per [43] Just south of Victoria, British Columbia it intersects the west-striking Devils Mountain Fault (reviewed above), and either merges with it,[44] or crosses (and possibly truncates) it to connect with the Leech River Fault. Piecing together the puzzle of the Seattle Fault Zone And the magnitude used to generate that wave is only about 7.5, as opposed to a magnitude-9 earthquake off the coast. slope, need not be high. Tacoma's Gain is Seattle's Pain. Crustal Faults | Pacific Northwest Seismic Network A different mountain and fault zone of the same name are located near Pasco; see QFFDB Fault #565), The southern end of Rattlesnake Mountain is truncated at the OlympicWallowa Lineament (OWL), and the faults turn easterly to merge with the OWL. [221] Where it might run south of Seattle is not known; an argument has been made that it runs beneath Seattle[222] but this is still conjectural.
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