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. The apparent gap north of Riffe Lake is possibly due to obscuration by volcanic deposits of the Northcraft Formation. Saint Helens and Mt. [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. 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. Let's make your home safer [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. 1 - 10 of 77 American Spirit Cruise Reviews. [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. 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). ISNS Ch 5 Flashcards | Quizlet And the magnitude used to generate that wave is only about 7.5, as opposed to a magnitude-9 earthquake off the coast. Read More. This formation, up to 15km thick, is largely buried (from one to ten kilometers deep), and known mainly by magnetotellurics and other geophysical methods. TTY Relay 711. Initially it was not specified, and rather vaguely indicated to be west of Restoration Point (i.e., west of Puget Sound). The Puget Sound region is not just potentially seismic, it is actively seismic. Turkey's fault line is similar to faults under Puget Sound 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. 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. [29] This prospect is especially intriguing as a possible explanation of a cluster of seismic events around 1100 years ago.[30]. [45] The Leech River Fault has been identified as the northern edge of the Crescent Formation (aka Metchosin Formation, part of the Siletzia terrane that underlies much of western Washington and Oregon). But their significance to the Puget Sound area is unknown. "Most often, when we think of tsunamis, we think of our outer coast and communities along the Pacific Ocean. KUOW Public Radio on Twitter: "A UW researcher says the fault line that 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 . [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). 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. See. The answer is still unresolved. [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]. Posted: 12 days ago. The Cascadia Fault is 620 miles long off the coast of Washington and British Columbia. Earthquake - King County Geologic Map. Turkey's Fault Line is Similar to Faults Under Puget Sound | KUOW Officials on Tuesday said they believe that more than 7,000 people are dead after a magnitude 7.8 earthquake shook southern Turkey, near the Turkish-Syrian border. 10+ Cruises Age 2020s. UW researchers model tsunami hazards on the Northwest coast Strawberry Point and Utsalady Point faults, "The Puget Lowland is a north-south-trending structural basin that is flanked by Mesozoic and Tertiary rocks of the Cascade Range on the east and by Eocene rocks of the Olympic Mountains on the west. In 1870, as construction of the Northern Pacific began, Seattle numbered fewer than 1,200 souls. 48), along the edge of a formation known as the Southern Washington Cascades Conductor. This is just after the terrane carrying the Olympic Mountains came into contact with the North American continent. 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. Simply put, the basement rock on the west side of Puget Sound does not match the basement rock on the east side. It's due for another one,. If, as this model suggests, the various faults are interconnected within the thrust sheet, there is a possibility that one earthquake could trigger others. 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. [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. Though these faults have been traced for only a little ways, the southeast striking anticlines they are associated with continue as far as Riffe Lake, near Mossyrock. Marine seismic reflection surveys on either side of Whidbey Island extend the known length of these faults to at least 26 and 28km (about 15 miles). 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. PNSN staff will continue to develop this section of the web site but to find more good information now, visit these resources: (Links with more information on various hazards can be found at Seattle Fault.). The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about magnitude 7 - an event that entered Native American oral legend. 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 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. Nurse Recruiter at VA Puget Sound health care, 206-764-2487. San Juan Island hopping on the Puget Sound, WA. The western flank of the Seattle Uplift forms a strong gravitational, aeromagnetic, and seismic velocity gradient known as the Dewatto lineament. (Their model of the Black Hills Uplift is analogous with their "wedge" model of the Seattle Uplift, discussed above, but in the opposite direction. 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. North Olympic Peninsula VA Clinic at VA Puget Sound health care, 360-565-7420. 112 earthquakes in the past 365 days. Part of the Snohomish River Delta between Everett and Marysville could get nearly 6 feet, and Seattle's Harbor Island could be inundated with nearly 4 feet of water. 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. This fault seems to be associated with the Kingston arch anticline, and part of the uplift and basin pattern, but shortened because of the geometry of the SWIF. Aeromagnetic surveys,[13] seismic tomography,[14] and other studies have also contributed to locating and understanding these faults. Extensive research has since shown the Seattle Fault to be part of a regional system of faults . 1 earthquake in the past 7 days. [91] The relationship between these two fault zones is not entirely clear. ISNS 2359 Earthquakes and Volcanoes Chapter 5 Questions - Quizlet $30-$33/hr Electrician Job at University of Puget Sound [44] Another problem with the SWIF/RMFZ as CRBF is that a large westward step is required to connect from the RMFZ to the Saint Helens Zone (SHZ; see map), whereas the RMFZ turns easterly to align with the OWL. Study of surface deformation suggests possible unmapped faults near Federal Way, running between Sumner and Steilacoom, and south of Renton.[223]. Please follow the steps below: . 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. Seattle Fault Bigger Quake Threat Than Thought | Live Science 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 geology also suggests that the DMF is moving obliquely up a ramp that rises to the east,[35] possibly an ancient coastal shore. [125] While some coherency is developing, the story is not complete: identified faults do not yet account for much of the region's seismicity. 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. Modeling a Magnitude 7.2 Earthquake on the Seattle Fault Zone in [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". [98] This turns and runs just south of Victoria, nearly in-line with the SWIF. 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 . South of Monroe the folds of the Rogers Belt are obscured by subsequent volcanic formations, but other faults parallel to the RMFZ (e.g., the Snoqualmie Valley and Johnson's Swamp fault zones) extend the general trend of NNW faulting as far as Monroe. The Doty Fault/Chehalis Basin sequence follows the cross-section X-X' shown on the, The long-range mapping plan area and current status of planned mapping can be seen at, For the County's interpretation of the geological hazard and anticipated impacts of a major earthquake, see the, Interstate 5 runs nearly due north from Everett to Mount Vernon, except for a stretch southeast of Conway that parallels one of these low-amplitude folds. They are also on-strike with a swarm of faults on the Columbia River, bracketing The Dalles. [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). However, an enormous threat lurks just off the coast of the Pacific Northwest. 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. Crustal Faults | Pacific Northwest Seismic Network The lowest exposed strata of Tiger Mountain, the mid-Eocene marine sediments of the Raging River formation, may be correlative with the SWCC. The Seattle Fault is a zone of complex thrust and reverse faults between lines E and F on the map up to 7km wide and over 70km long that delineates the north edge of the Seattle Uplift. [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. This is being obliquely overridden by the North American plate coming out of the northeast, which has formed a bend in the subducting plate and in the forearc basin above it. Some of these faults possibly developed in the Mesozoic, when these deposits were in the accretionary wedge;[72] the cross-cutting NE and NNE-striking faults that form the various basins resulted from a subsequent change to transtension. The map also shows potentially active faults from a separate 2014 report (click here to download). slope, need not be high. [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. [39] On the basis of marine seismic reflection surveying in the Strait of Juan de Fuca it has been suggested that the DMF, SPF, and UPF are structurally connected (at least in the segment crossing Whidbey Island). King County Emergency Management. . 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. Sail Date: October 2022 . A similar line aligns with the termination of the WRZ, SHZ, and Gales Creek Fault Zone (northwest of Portland), with faulting along the upper Nehalem River on the Oregon coast,[211] and a topographical contrast at the coast (between Neahkahnie Mountain and the lower Nehalem River valley) distinct enough to be seen on the seismicity map above (due west of Portland). 4) Drag square on line to include events to plot. Especially as seismic reflection data[135] shows some faulting continuing east across Vashon Island and the East Passage of Puget Sound (the East Passage Zone, EPZ) towards Federal Way and an east-striking anticline. 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. [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. Review for American Constellation to U.S.A. chatuga. [141] (Originally named the Tahuya Fault. Seattle Fault - Wikipedia 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. [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. [118], Studies of the Seattle Fault west of Bremerton have revealed a complexity of geological structure and faulting. In this model the Tacoma fault zone is primarily the result of local adjustments as the slab bends upward at the bottom of the ramp. We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Nurse Information Line at VA Puget Sound health care, 800-329-8387 x4. There are numerous other faults (or fault zones) in the Puget Lowland, and around its edges, sketchily studied and largely unnamed. Plot. Earthquake - Emergency Management | seattle.gov The Pacific Northwest Seismic Network (PNSN) reported at least three earthquakes within the past few days. 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. [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. [129] The western part is an active eastwest striking north dipping reverse fault that separates the Seattle Uplift and the Tacoma Basin, with approximately 30 miles (50km) of identified surface rupture. The mapped surface traces are only 5km long, but LIDAR-derived imagery shows longer lineaments, with the traces cutting Holocene alluvial traces. ), Aeromagnetic mapping in 1999 showed a very prominent anomaly[172] (such as typically indicates a contrast of rock type); that, along with paleoseismological evidence of a major Holocene earthquake, has led to a suggestion that this structure "may be associated with faulting". These features suggest that the southern Puget Lowland is influenced by the deep crust and even the subducting Juan de Fuca plate, but the details and implications are not yet known. 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. WASHINGTON: Methane Bubbles Up From Seafloor Near Seattle The energy of the somewhat smaller Benioff earthquakes is likewise diluted over a relatively large area. Washington's faults: Where the Earth moves the Seattle area . 09 Feb 2023 03:01:00 [88] (See the adjacent map. Base map is hillshaded DEM derived from LiDAR data (pixel size 1.8 m) from Puget Sound LiDAR Consortium; illumination from azimuth 05, at 5 above the horizon; datum is NAD83, UTM zone 10N. 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. [198], Does the SHZ extend north? Sail Date . Those Hollywood depictions of a. 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.
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