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. (Enter only one word per blank.) The last large event was in 1700, but there is a 37 percent chance of an 7.1+ in the next 50 years. . Page 2 of 4 / 2012-2013 Type of Earthquake Most earthquake hazards result from ground shaking caused by seismic waves that radiate out from a fault when it ruptures. [38] These earthquakes probably caused tsunamis, and several nearby locations have evidence of tsunamis not correlated with other known quakes. While there is a short zone (not shown) of fainter seismicity near Goat Rocks (an old Pliocene volcano[196]) that may be associated with the contact, the substantially stronger seismicity of the WRZ is associated with the major Carbon RiverSkate Mountain anticline. This map of Puget Sound shows the location of the methane plumes as yellow and white circles. [190] These faults also cross the Saint Helens Zone (SHZ), a deep, north-northwest trending zone of seismicity that appears to be the contact between different crustal blocks. Washington's faults: Where the Earth moves the Seattle area Tobin says offshore faults tend to cause bigger earthquakes and are a larger tsunami risk. 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. Puget Sound Earthquake Faults - Seattle Earthquake Faults Turkey's fault line is similar to faults under Puget Sound Folding and faulting has exposed these basalts in some places (black areas in diagram); the intervening basins have been filled by various sedimentary formations, some of which have been subsequently uplifted. and Fault Location. 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. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. [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. [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. Earthquake Hazard Maps | Sound Seismic 3511 NE Second St. Renton, WA 98056. 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. [72] The WMB is an assemblage of Late Jurassic and Cretaceous rock (some of it as much as 166 million years old) collected in the accretionary wedge (or prism) of a subduction zone. They interpreted it as "simple folds in Eocene bedrock", though Sherrod (1998) saw sufficient similarity with the Seattle Fault to speculate that this is a thrust fault. Scientists Search for New Faults in Puget Sound 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. Fault line puts Seattle at risk of 'The Big One' - UW Magazine 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. 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. The Puget Sound Region is crisscrossed by fault lines and zones and also located close to the Cascadia Subduction Zone, where the Juan de Fuca and North American tectonic plates meet. [9] Not until 1992 was the first of the lowland faults, the Seattle Fault, confirmed to be an actual fault with Holocene activity, and the barest minimum of its history established.[10]. Tsunami waves would reach Seattle within minutes after earthquake West of Puget Sound the tectonic basement of the Coast Range geologic province is the approximately 50 million year (Ma) old marine basalts of the Crescent Formation, part of the Siletzia terrane that underlies western Washington and Oregon. 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. 206-296-3830. These are usually fairly short, and not believed to be significantly seismogenic. "[50], The contrast of seismic velocities seen to the northwest is lacking in this section, suggesting that it is not the Coast RangeCascade contact. Crustal Faults | Pacific Northwest Seismic Network In the wedge model of Pratt et al. [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. With inland, Puget Sound faults, like the Seattle Fault, the risk is comparatively smaller. The Doty fault has been mapped from the north side of the Chehalis airport due west to the old logging town of Doty (due north of Pe Ell), paralleled most of that distance by its twin, the Salzer Creek Fault, about half a mile to the north. 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. At the northern end the right-lateral McMurray Fault Zone (MFZ) straddles Lake McMurray, just south of the Devils Mountain Fault, and is suspected of being a major bounding fault. Glacially deposited and shaped fill covers most of the lower elevations of Puget Sound. The most striking concentrations of mid-crustal seismicity in western Washington outside of Puget Sound are the Saint Helens Zone (SHZ) and Western Rainier Zone (WRZ) at the southern edge of the Puget Lowland (see seismicity map, right). In the previous study seismicity, surface geology, and geophysical data were modeled in order to examine the fault structuring of the upper crust. [143] Such interconnection also suggests a capability for larger earthquakes (> M7 for the Seattle Fault); the amount of increased risk is unknown.[144]. Geochemistry, Geophysics, Geosystems , 2021; 23 (1) DOI: 10.1029/2021GC010211 Cite This Page : It is believed capable of generating earthquakes of at least magnitude 7, and there is evidence of such a quake approximately 1,000 years ago, possibly the same earthquake documented on the Seattle Fault 24 miles (38km) to the north. (1997), while observing the "remarkable straight boundaries that we interpret as evidence of structural control",[171] refrained from calling this structure a fault. Sail Date: October 2022 . It appears that the Seattle Uplift is acting as a rigid block, with the Tacoma, Dewatto, and Seattle faults being the southern, western, and northern faces. Analyze Instructions: Close. Tacoma's Gain is Seattle's Pain. Puget Sound faults - Wikipedia Geographic boundaries of Puget Sound and the Salish Sea The uplift and basin pattern is continued to the west and southwest by the Grays Harbor Basin, Willapa Hills Uplift, and Astoria Basin,[25] but it is not known if these are bounded by faults in the same manner as in the Puget Sound region. [180], That Olympia and the south Sound are at risk of major earthquakes is shown by evidence of subsidence at several locations in southern Puget Sound some 1100 years ago. Nurse Information Line at VA Puget Sound health care, 800-329-8387 x4. [112] But if the Seattle Fault should break in conjunction with other faults (discussed above), considerably more energy would be released, on the order of ~M 8. A Seattle Fault quake could be as large as M7.5,160 but less than M7.0 is more probable. The length of the Doty Fault is problematical: the report in 2000 gave it as 65km (40 miles), but without comment or citation. Five Puget Sound cities likely to feel strong shaking in a megaquake Get directions. The energy released depends on the length of the fault; the faults here are believed capable of generating earthquakes as great as M 6 or 7. The ultimate driver of the stresses that cause earthquakes are the motions of the tectonic plates: material from the Earth's mantle rises at spreading centers, and moves out as plates of oceanic crust which eventually are subducted under the more buoyant plates of continental crust. However, the Hood Canal fault has been "largely inferred"[147] due to a paucity of evidence, including lack of definite scarps and any other signs of active seismicity. fault Which of the following statements best describes elastic-rebound theory? [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. The DotySalzer Creek Fault does not fully fit the regional pattern of basins and uplifts bounded by faults described above. slope, need not be high. Review for American Constellation to U.S.A. chatuga. Devils Mountain Fault Zone, Northern Puget Sound, Washington The principal effects of this complex interplay of forces on the near-surface crust underlying the Puget Lowland are: Further complicating this is a feature of unknown structure and origin, the OlympicWallowa Lineament (OWL). [52], Subsequent mapping shows the SWIF wrapping around the eastern end of the Seattle Basin to merge with the Rattlesnake Mountain Fault Zone (RMFZ); the RMFZ, despite the approximately 15 bend and different context, is now believed to be the southern extension of the SWIF. Interpretation of the eastern part of the Tacoma Fault is not entirely settled. 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. 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. [Paper No. Publication Year: 2010: Title: A magnitude 7.1 earthquake in the Tacoma Fault Zone A plausible scenario for the southern Puget Sound region, Washington: DOI: 10.3133/fs20103023: Authors: 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. 64, on-line) that the edge of the Crescent Formation offsets west along the Seattle Fault, with the Seattle Basin resulting from a gap between the main part of Siletiza and a northern block that has broken away. For information about the Energize Eastside project, . Slippage along the SWIF would be expected to continue east-southeast until it merged with the OWL, but instead appears to be taking a shortcut ("right step") along the RMFZ. [61], North of Everett is an area of parallel ridges and stream drainages oriented approximately NW-SE, evident even on non-geological maps. This follows the front of the Rosedale monocline, a gently southwest-tilting formation that forms the bluffs on which Tacoma is built. 20);[208] it includes the Cherry Creek Fault Zone NNE of Carnation, location of the 1965 Duvall earthquake. Puget Sound Tsunami Simulation - National Oceanic and Atmospheric Study: Tsunami from Cascadia mega-quake would submerge Puget Sound These maps are based on only one Cascadia scenario. [109] It extends as far east as (and probably terminates at) the Rattlesnake Mountain Fault Zone (RMFZ; the southern extension of the SWIF) near Fall City. If, as this model suggests, the various faults are interconnected within the thrust sheet, there is a possibility that one earthquake could trigger others. WASHINGTON: Methane Bubbles Up From Seafloor Near Seattle Several possible explanations of the enhanced conductivity have been considered; Eocene marine sediments containing brine are most likely (. 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 . The Seattle Fault crosses east-west through Puget Sound and downtown Seattle. [95], (Rattlesnake Mountain Fault Zone not included in QFFDB. Click a second point on the map, this will be the right side of the cross-section. [133] The Tacoma fault was initially suspected of following a weak magnetic anomaly west to the Frigid Creek fault,[127] but is now believed to connect with a steep gravitational, aeromagnetic, and seismic velocity gradient that strikes north towards Green Mountain (Blue Hills uplift). When the applied stresses become overpowering, the rocks at the fault rupture. These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) [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. Review for American Spirit to U.S.A. Gilliancruise. However, most seismic activity is not associated with any known fault. Most of these "faults" are actually zones of complex faulting at the boundaries between sedimentary basins (synclines, "") and crustal uplifts (anticlines, ""). [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. Geologic Hazard Maps | WA - DNR [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). - Read More Expert Puts Turkey, Syria Quake into Perspective | FOX 13 Based on this and geophysical anomalies it was inferred that there is a major, active strike-slip fault zone running from the south end of Hood Canal, up Dabob Bay, and continuing north on land. Active tectonics of the Seattle fault and central Puget sound Fault lines in the New Madrid seismic zone are being mapped, thanks in part to . 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]. The history and capabilities of the Frigid Creek Fault are not known. [206] This line may also mark the northwestern boundary of the SWCC. Seattle Earthquakes, Types of Quakes & Fault Lines - TripSavvy Shallow fault below Seattle went undiscovered for a millennium They run . One study compared the relative elevation of two marshes on opposite sides of Whidbey Island, and determined that approximately 3,000 years ago an earthquake of M 6.57.0 caused 1 to 2 meters of uplift. [174] Although no surface traces of faulting have been found in either the Holocene glacial sediments or the basalts of the Black Hills,[175] on the basis of well-drilling logs a fault has been mapped striking southeast from Offut Lake (just west of Rainier); it appears to be in line with the easternmost fault mapped in the CentraliaChehalis area.[176]. E.g., HH mlange rock has been found in Manastash Ridge, 110km to the south (look for the small sliver of purple near the bottom of the diagram). See Snavely et al. [51] 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. Offsets in the eastwest oriented Monroe Fault (south side of the Skykomish River), earthquake focal mechanisms, and kinematic indications show that the CCFZ is a left-lateral strike-slip fault, possibly with some oblique motion (up on the eastern side). [85] The Tokul Creek Fault (TCF) strikes NNE from Snoqualmie, aligned with a possible offset of the Western Melange Belt[86] and with a valley that cuts through to the Skykomish River; it is now believed to be of regional significance. Bubbles of methane rising from seafloor in Puget Sound Although these faults are west of the Hood Canal Fault (previously presumed to be the western boundary of the Puget Lowland), new studies are revealing that the Saddle Mountain and related faults connect with the Seattle fault zone. A parallel line ("B") about 15 miles (25 kilometers) to the west corresponds to the western limit of a zone of seismicity stretching from the WRZ to southwest of Portland. An earthquake occurs along a south-moving fault. [125] While some coherency is developing, the story is not complete: identified faults do not yet account for much of the region's seismicity. Railroad Development in the Seattle/Puget Sound Region, 1872-1906 In 1870, as construction of the Northern Pacific began, Seattle numbered fewer than 1,200 souls. The structure of the Seattle Fault zone still have great uncertainty and there exist a number of interpretations. Puget Sound Energy Maps and Records Non-Disclosure Agreement: (NDA ONLY) ko ru zh es vi hi: PSE Map Request Form and Non-Disclosure Agreement: 07/29/2022: 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). It is believed that all of these faults, folds, basins, and uplifts are related. [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. . [58], Paleoseismological studies of the SWIF are scant. Seattle Fault Bigger Quake Threat Than Thought | Live Science Most people in the United States know just one fault line by name: the San Andreas, which runs nearly the length of California and is perpetually rumored to be on the verge of unleashing "the. [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. Because the Seattle and Tacoma faults run directly under the biggest concentration of population and development in the region, more damage would be expected, but all the faults reviewed here may be capable of causing severe damage locally, and disrupting the regional transportation infrastructure, including highways, railways, and pipelines. "[31] More particularly, the concentration of seismicity under Puget Sound south of the Seattle Fault is attributed to uplift of that block, bounded by the Seattle, Tacoma, and Dewatto faults on the north, south, and west (the eastern boundary is not determined), creating the Seattle Uplift. [90], The RMFZ continues NNW past Fall City and Carnation, where strands of the RMFZ have been mapped making a gentle turn of 15 to 20 west to meet the Southern Whidbey Island Fault zone (SWIF, discussed above); the RMFZ is therefore considered to be an extension of the SWIF. 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. This is only one of a series of active large crustal faults in the Puget Lowland. Sail Date . The Doty fault particularly seems to have gained prominence with geologists since it was associated with an aeromagnetic anomaly,[184] and a report in 2000 credited it capable of a magnitude 6.7 to 7.2 earthquake. Yet the former is only the first of at least six more parallel southeast striking faults, which do cross the Salzer Creek Fault. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. See. [75], The strongly expressed topographical lineaments at the north end of the Rogers Belt pose a perplexing problem, as they show no definite offset where they are bisected by the left-lateral oblique-slip Devils Mountain Fault. The western flank of the Seattle Uplift forms a strong gravitational, aeromagnetic, and seismic velocity gradient known as the Dewatto lineament. [88] (See the adjacent map. [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. If the pattern is continued to the southwest, along cross-section A-A' in Pratt's figure 11 (and missing the mapped trace of the Doty Fault), then the next basin is at Grays Harbor (not shown here). [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. ), The Coast Range Boundary Fault (CRBF) is hypothesized, expected on the basis of tectonic considerations, which may correlate in part with one or more currently known faults, or may involve as yet undiscovered faulting. They are also on-strike with a swarm of faults on the Columbia River, bracketing The Dalles. 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). Since 2000 studies of LIDAR and high-resolution aeromagnetic data have identified scarps near Woodinville which trenching has confirmed to be tectonically derived and geologically recent.
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