fault lines in puget sound
One animation shows the expected path of a Puget Sound tsunami generated by a quake on the Seattle Fault. South of the OWL a definite eastern boundary has not been found, with some indications it is indefinite. This pocket is catching a stream of terranes (crustal blocks about 20 to 30km thick[18]) which the Pacific plate is pushing up the western edge of North America, and in the process imparting a bit of clockwise rotation to southwestern Washington and most of Oregon; the result has been characterized as a train wreck. 1 earthquake in the past 7 days. Today's Earthquakes in Olympic Peninsula, Washington [106] There is an intriguing view from Stanley, Villaseor & Benz (1999) (see Fig. 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. The worst of the tsunami would hit the Pacific Coast and San Juan Islands area but the interior of Puget Sound between Edmonds, Tacoma, and Hoodsport could see waves 10 feet or higher, the. and Fault Location. [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. Puget Sound Earthquake Faults - Seattle Earthquake Faults Puget Sound Energy. (A) Map of the Seattle fault zone (SFZ) in the central Puget Sound . [98] This turns and runs just south of Victoria, nearly in-line with the SWIF. 4 earthquakes in the past 30 days. Full-Time. [153] For these reasons this is now a questioned fault, and is indicated on the map as a dashed line. slope, need not be high. Large plumes of methane bubbles have been discovered throughout the waters of Puget Sound prompting questions about the Puget Sound food web, studies of earthquake faults and climate-change research. PNSN staff will continue to develop this section of the web site but to find more good information now, visit these resources: Those Hollywood depictions of a. The energy of the somewhat smaller Benioff earthquakes is likewise diluted over a relatively large area. 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 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. 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. American Seattle Cruise Reviews - Cruise Critic ), 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. Bubbles of methane rising from seafloor in Puget Sound See Snavely et al. 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). The Devils Mountain Fault separates two similar but distinctive ensembles of Mesozoic (pre-Tertiary, before the dinosaurs died) or older rock. And in between these two the Strawberry Point Fault (SPF) skirts the south side of Ault Field, splits into various strands that bracket Strawberry Point, and then disappear (possibly ending) under the delta of the Skagit River. 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 . [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. There are other tsunami scenarios that are not accounted for in these maps, such as tsunamis caused by . 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). A principal finding is that "[c]rustal seismicity in the southern Puget Sound region appears to be controlled by a key block of Crescent Formation occurring just south of the Seattle fault. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault Calawah fault Barnes Creek With inland, Puget Sound faults, like the Seattle Fault, the risk is comparatively smaller. 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). The Devils Mountain Fault is seismically active, and there is evidence of Holocene offsets. When the applied stresses become overpowering, the rocks at the fault rupture. [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. [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 largest intra-crustal earthquakes have about the same total energy (which is about one-hundredth of a subduction event), but since they are closer to the surface they will cause more powerful shaking, and, therefore, more damage. [182], The Doty Fault the southernmost of the uplift-and-basin dividing faults reviewed here, and located just north of the Chehalis Basin is one of nearly a dozen faults mapped in the CentraliaChehalis coal district in 1958. "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 . Black lines show the South Whidbey Island Fault Zone, the . Rainier, along the DDMFZ, and under Puget Sound between Olympia and approximately the Southern Whidbey Island Fault. (Not included in QFFDB. The Puget Sound region is not just potentially seismic, it is actively seismic. [32] And it is suggested that the Great Seattle Quake of approximately 1,100 years ago, and other coseismic events in southern Puget Sound around that time, were a single event that affected this entire block, with a magnitude of around 8, possibly triggered by an earthquake deeper in the crust.[33]. They estimate the fault is within a few miles of the surface and was active as recently as 1,000 to 1,100 years ago. Tobin says offshore faults tend to cause bigger earthquakes and are a larger tsunami risk. Geographic boundaries of Puget Sound and the Salish Sea [123] Other studies have faults extending NW or WNW from the SF towards Dabob Bay;[124] these are now recognized as part of the Dabob Bay fault zone. 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). That earthquake, likely between magnitude 7 and 7.5, lifted the southern end of Bainbridge Island and West Seattle more than 20 feet (3 meters), generated a tsunami, and created landslides into Lake Washington, says Bill Steele . Review for American Spirit to U.S.A. Gilliancruise. (See, There is a preliminary report of aeromagnetic and gravity mapping placing the eastern edge of the Siletz terrane under Lake Washington. Locations of some previously mapped faults have been adjusted on the latest map. This bend has distorted the subducting slab into an arch that has lifted the Olympic Mountains and prevented them from subducting. [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. [62] These ridges (part of a broader regional pattern that reflects the roots of the former Calkins Range[63]) are formed of sediments that collected in the Everett basin during the Eocene, and were subsequently folded by northeast-directed compression against the older Cretaceous and Jurassic rock to the east that bound the Puget Lowland. Gonzalez: That Seattle Fault tsunami has been modeled by others. Review for American Constellation to U.S.A. chatuga. 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. 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]. [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. Today's Earthquakes in Puget Sound, Washington The Earthquake That Will Devastate the Pacific Northwest These lineaments have been associated with possible zones of faulting in the crust and subducting plate.[212]. 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. The implications of this are not only "the possibility of a moderate to large crustal earthquake along the SHZ", but that the tectonics under Puget Sound are more complicated than yet understood, and may involve differences in the regional stress patterns not reflected in current earthquake hazard assessments. [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. Tsunami waves would reach Seattle within minutes after earthquake [6] The first definite indications of most of these faults came from gravitational mapping in 1965,[7] and their likely existence noted on mapping in 1980 and 1985. 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. These faults are: the Kopiah Fault (note the curious curve), Newaukum Fault, Coal Creek Fault, and three other unnamed faults. 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. Puget Sound and San Juan islands. A magnitude 7.1 earthquake in the Tacoma Fault Zone A - USGS [46] Seismic tomography studies show that this portion of the SWIF marks a strong contrast of seismic velocities, such as is expected of Crescent Formation basalts in contact with the metamorphic basement rocks of the Cascades geologic province to the east. Glacially deposited and shaped fill covers most of the lower elevations of Puget Sound. 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. Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc. Mapping from the Pacific Northwest Seismic Network shows that the bulk of the earthquakes in western Washington are concentrated in four places: in two narrow zones under Mt. [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. The SWCC appears to be Tertiary marine sediments, not the pre-Tertiary metamorphic rock of the Cascades province; this would seem to make it part of the Coast Range province, with the Coast RangeCascade contact further east. It is believed that all of these faults, folds, basins, and uplifts are related. [53] Reckoned between Victoria and approximately Fall City the length of the SWIF is around 150km (90 miles). [143] Such interconnection also suggests a capability for larger earthquakes (> M7 for the Seattle Fault); the amount of increased risk is unknown.[144]. Puget Sound Lidar Consortium Finding faults scarp(n). San Juan Island hopping on the Puget Sound, WA. I've been in the business for 20 years and the way skilled labor has been treated up until very recently drove a ton of people away from the industry. 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]. [96] As the juxtaposition of various disparate tectonic structures in northwest Washington requires significant strike-slip movement, it is further expected that this contact will be a major fault.[97]. [193] The SHZ and WRZ lie just outside the topographical basin that constitutes the Puget Lowland (see image), do not participate in the uplift and basin pattern, and unlike the rest of the faults in the Puget Lowland (which are reverse or thrust faults reflecting mostly compressive forces) they appear to be strike-slip faults; they reflect a geological context distinctly different from the rest of the Puget Lowland. 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. Modeling a Magnitude 7.2 Earthquake on the Seattle Fault Zone in This may explain why the Seattle and Tacoma faults seem to have ruptured at nearly the same time.[127]. 112 earthquakes in the past 365 days. The map is from a 2007 report (click here to download) on seismic design categories in Washington. Geologic map of southwestern Washington (GM-34). The lowest exposed strata of Tiger Mountain, the mid-Eocene marine sediments of the Raging River formation, may be correlative with the SWCC. Display Faults. Also, the sedimentary Chuckanut Formation (part of the NWCS, green) north of the DMF correlates to the Suak and Roslyn Formations just north of Manastash Ridge. This section of the SWIF forms the southwestern side of the Everett Basin[48] (see map), which is notably aseismic in that essentially no shallow (less than 12km deep) earthquakes have occurred there, or on the section of the SWIF adjoining it, in the first 38 years of instrumental recording. These faults are not quite aligned with the Olympia structure, striking N75W (285) rather than N45W (315). 6 earthquakes in the past 7 days. Contact Us | VA Puget Sound Health Care | Veterans Affairs The Olympia structure also known as the Legislature fault[168] is an 80km long gravitational and aeromagnetic anomaly that separates the sedimentary deposits of the Tacoma Basin from the basalt of the Black Hills Uplift (between lines A and B on the map). 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. fault Which of the following statements best describes elastic-rebound theory? From the north these are (see the map at right): The Hood Canal Fault (and its possible extensions) and Saddle Mountain faults to the west are believed to form the western boundary to all this. The Cascadia Fault is 620 miles long off the coast of Washington and British Columbia. 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. This is only one of a series of active large crustal faults in the Puget Lowland. Sail Date: October 2022 . The Seattle fault isn't a single strand, but a zone of subterranean fractures that extends across Puget Sound, passing under Seattle and reaching as far east as Issaquah. "[50], The contrast of seismic velocities seen to the northwest is lacking in this section, suggesting that it is not the Coast RangeCascade contact. Seattle Fault Bigger Quake Threat Than Thought | Live Science These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. This map shows the primary earthquake faults in the Puget Sound and other less prominent faults. 182-3]", "Western limits of the Seattle fault zone and its interaction with the Olympic Peninsula, Washington", "Seismic reflection imaging across the eastern portions of the Tacoma fault zone", "The western extension of the Seattle fault: new insights from seismic reflection data", "Seismic Characterization of the Seattle and Southern Whidbey Island Fault Zones in the Snoqualmie River Valley, Washington", "Fault number 552, Hood Canal fault zone", "Radiocarbon Ages of Probable Coseismic Features from the Olympic Peninsula and Lake Sammamish, Washington", "Geologic map of the Summit Lake 7.5-minute quadrangle, Thurston and Mason Counties, Washington", "The Olympia structure; ramp or discontinuity? [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. 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. [74], Early Eocene igneous units in the area appear to be part of a 49- to 44- Ma magmatic belt that appeared just after the arrival of Siletzia, and possibly associated with that event. 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). Earthquakes occur nearly every day in Washington. 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. In some places, such as along the South Fork of the Stillaguamish River between Arlington and Granite Falls, there are also contrasting geological contacts. 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. 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). Olympic Peninsula, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours.