. 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. East of Puget Sound the basement of the Cascades province is various pre-Tertiary (older than 65 Ma) metamorphic rock. King County Emergency News. The Devils Mountain Fault separates two similar but distinctive ensembles of Mesozoic (pre-Tertiary, before the dinosaurs died) or older rock. 1 earthquake in the past 7 days. This follows the front of the Rosedale monocline, a gently southwest-tilting formation that forms the bluffs on which Tacoma is built. Site Info - Earth and Space Sciences - University of Washington The Pacific Northwest Seismic Network (PNSN) reported at least three earthquakes within the past few days. [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). 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. Over 7,000 people are dead after a magnitude 7.8 earthquake shook southern Turkey, near the Turkish-Syrian border. ISNS 2359 Earthquakes and Volcanoes Chapter 5 Questions - Quizlet [47], To the southeast the SWIF passes through Admiralty Inlet (past Port Townsend) and across the southern part of Whidbey Island, crossing to the mainland between Mukilteo and Edmonds. 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. 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. Recent EQ List [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. In some places, such as along the South Fork of the Stillaguamish River between Arlington and Granite Falls, there are also contrasting geological contacts. 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. Seattle Fault - Wikipedia These mlanges may have been off-shore islands or seamounts that were caught between the Olympic terrane and the North American continent, and were pushed up (obducted) onto the latter. Despite not having active plate tectonics, the eastern United States still experiences earthquakes. 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. Simply put, the basement rock on the west side of Puget Sound does not match the basement rock on the east side. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. 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. [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. [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. Job Description. 09 Feb 2023 03:01:00 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. 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 ramp could be either in the lower crustal blocks, or where the thrust sheet has split and one part is being forced over the next. The Seattle fault zone is where the forward edge of the slab, coming to the top of the ramp, breaks and slips into the Seattle Basin. [173] One reason for caution is that a detailed gravity survey was unable to resolve whether the Olympia structure is, or is not, a fault. More than a millennium ago, a quake estimated at a magnitude 7 on the Seattle Fault thrust land upward as much as 23 feet and submerged 200-acre chunks of forest in central Puget Sound and Lake . These are usually fairly short, and not believed to be significantly seismogenic. If, as this model suggests, the various faults are interconnected within the thrust sheet, there is a possibility that one earthquake could trigger others. In the angle between these is located the minor Lincoln Creek uplift, the Doty Hills, and, further west, an impressive chunk of Crescent basalt. These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) 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. Modeling a Magnitude 7.2 Earthquake on the Seattle Fault Zone in There is no firm evidence that this has occurred in the Seattle fault zone near Puget Sound, although a low terrace of 1 m or less formed during a moderate earthquake would be difficult to. ", Because of the geometry of the SWIF and the Kingston arch, the "uplift of unknown origin" between them is smaller, and the fault separating the uplift from the arch (the Lofall Fault, discovered relatively recently by, Strictly speaking the southern edge of the Black Hills Uplift would be the southeast striking Scammon Creek Fault that converges with the east striking Doty Fault at Chehalis. Methane Plume Emissions Associated With Puget Sound Faults in the These maps are based on only one Cascadia scenario. Earthquake Fault Maps in Seattle and Washington State Read More. News Media at VA Puget Sound health care, 206-764-2435, 206-764-2317. The alternative, that younger faulting in the Rogers Belt has offset the DMF Cheney argued that the MVF had offset the DMF 47km. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. One animation shows the expected path of a Puget Sound tsunami generated by a quake on the Seattle Fault. [27] This "basement" rock is covered with sedimentary deposits similar to the Chuckanut Formation, and more recent (typically Miocene) volcanic deposits. Geographic boundaries of Puget Sound and the Salish Sea [51] 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]. Aeromagnetic surveys,[13] seismic tomography,[14] and other studies have also contributed to locating and understanding these faults. 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. Review for American Constellation to U.S.A. chatuga. This is a seemingly accidental alignment of topographic features that runs roughly east-southeast from the north side of the Olympic Peninsula to the Wallowa Mountains in northeastern Oregon. [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]. [107], The Seattle Fault was first identified in 1965[108] but not documented as an active fault until 1992 with a set of five articles establishing that about 1100 years ago (AD 900930) an earthquake of magnitude 7+ uplifted Restoration Point and Alki Point, dropped West Point (the three white triangles in the Seattle Basin on the map), caused rockslides in the Olympics, landslides into Lake Washington, and a tsunami on Puget Sound. [71], These faults cut through the Western Mlange Belt (WMB; blue area in map), exposed from North Bend (on Interstate 90) to Mount Vernon. The history and capabilities of the Frigid Creek Fault are not known. Puget Sound Energy transmission line project Energize Eastside. TTY Relay 711. This fault produced a large earthquake that left a geologic record of surface offsets about 1100 years ago. 2-5 Cruises Age 60s. Fault line puts Seattle at risk of 'The Big One' - UW Magazine Puget Sound Earthquake Faults - Seattle Earthquake Faults 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. 1958 and Geologic Map GM-34 for details.). [158] Vertical movement on these faults has created prominent scarps that have dammed Price Lake and (just north of Saddle Mountain) Lilliwaup Swamp. ISNS Ch 5 Flashcards | Quizlet Get directions. However, an enormous threat lurks just off the coast of the Pacific Northwest. It stands out in regard of its eastwest orientation, depth to bedrock, and hazard to an urban population center. These lineaments have been associated with possible zones of faulting in the crust and subducting plate.[212]. [53] Reckoned between Victoria and approximately Fall City the length of the SWIF is around 150km (90 miles). But it does not appear that there have been studies of the deeper structure of these faults, or whether there has been any recent activity. E.g., mapping along the Rattlesnake Mountain Fault Zone has revealed a complex network of active or potentially active faults across (and likely beyond) the lower Snoqualmie Valley, including the Cherry Creek Fault Zone, scene of the 1996 M 5.3 Duvall earthquake. 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. [102] Or the Crescent margin may simply (and quietly) just run south-southeast under Seattle to the WRZ. A Tsunami Hits Puget Sound: New Simulation Shows How It Unfolds [153] For these reasons this is now a questioned fault, and is indicated on the map as a dashed line. Please follow the steps below: . [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. In particular, to the southeast of Mount St. Helens and Mount Rainier they reflect a regional pattern of NNW oriented faulting, including the Entiat Fault in the North Cascades and the Portland Hills and related faults around Portland (see QFFDB fault map). The apparent gap north of Riffe Lake is possibly due to obscuration by volcanic deposits of the Northcraft Formation. Olympic Peninsula, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. 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. 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). [91] The relationship between these two fault zones is not entirely clear. 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. [19] These terranes were covered by the basalts of the Crescent Formation (part of Siletzia). "Most often, when we think of tsunamis, we think of our outer coast and communities along the Pacific Ocean. [139] The Dewatto linement extends from the western end of the Tacoma fault (see map immediately above) northward towards Green Mountain at the western end of the Seattle fault. In 1870, as construction of the Northern Pacific began, Seattle numbered fewer than 1,200 souls. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates . 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. The first item on your list though is the fault of builders and nobody else. 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). This MSH-MR-GP lineament is believed to reflect a "long-lived deep-seated lithospheric flaw that has exerted major control on transfer of magma to the upper crust of southern Washington for approximately the last 25 [million years]";[203] it has been attributed to the geometry of the subducting Juan de Fuca plate.[205]. The Earthquake That Will Devastate the Pacific Northwest The EPZ is active, being the locale of the 1995 M 5 Point Robinson earthquake.[136]. 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. [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. Whether the faulting continues eastward is not yet determined. [218] This would pose significantly greater seismic hazard than currently recognized, especially as the White River Fault is believed to connect with the Naches River Fault that extends along Highway 410 on the east side of the Cascades towards Yakima. Pratt et al. This is the Puget Lowland. Gonzalez: That Seattle Fault tsunami has been modeled by others. The DotySalzer Creek Fault does not fully fit the regional pattern of basins and uplifts bounded by faults described above. 1 - 10 of 77 American Spirit Cruise Reviews. Ancient quake and tsunami in Puget Sound shake researchers [16] For the past 50 million years or so (since the early Eocene epoch) these have been thrust by subduction up against the North Cascades ("fixed block" in the diagram), which sit on the North American Plate. The Devils Mountain Fault is seismically active, and there is evidence of Holocene offsets. And though the faults in this area are not notably seismogenic, the southeast striking faults seem to be en echelon with the Olympia structure (fault? Study: Tsunami from Cascadia mega-quake would submerge Puget Sound 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. [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. Seven times in the past 3,500 years, the CSZ has buckled and fractured to produce an earthquake so massive that it left a mark in the geologic record. 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). 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. Estimated shaking in the Puget Sound - Strange Sounds Posted: 12 days ago. This interpretation suggests that the Seattle Uplift acts as a rigid block, and possibly explains the kinematic linkage by which large earthquakes may involve ruptures on multiple faults: the Seattle, Dewatto, and Tacoma faults represent the northern, western, and southern faces of a single block. 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. It appears the entire DDMFZ and Leech River fault system was pushed onto the early continental margin from an original alignment along the OWL. [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). 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. They are also on-strike with a swarm of faults on the Columbia River, bracketing The Dalles. Today's Earthquakes in Olympic Peninsula, Washington [198], Does the SHZ extend north? Glacially deposited and shaped fill covers most of the lower elevations of Puget Sound. And like the SCF, strike-slip motion died out between 44 and 41 MA (due to plutonic intrusions). [29] This prospect is especially intriguing as a possible explanation of a cluster of seismic events around 1100 years ago.[30]. [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. [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. Toll Free 1-800-523-5044. Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc. A single earthquake in Seattle could cause a catastrophic situation for the northwest corner of the state, a new report from Washington's Department of Natural Resources found. 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. Plot Type: X-Section Depth Cumulative # Mag-Time. [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. Bubbles of methane rising from seafloor in Puget Sound - Phys.org The answer is still unresolved. 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. [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]. [160] The Canyon River Fault is a major fault in itself, associated with a 40km long lineament and distinct late Holocene scarps of up to 3 meters.[161]. It is not notably seismogenic. 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. ), 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. The northern end of the Crescent Formation (aka Metchosin Formation) has been identified as the eastwest trending Leech River Fault on the southern tip of Vancouver Island. The mapped surface traces are only 5km long, but LIDAR-derived imagery shows longer lineaments, with the traces cutting Holocene alluvial traces. [126], An emerging view is that the Dewatto fault marks the western edge of the relatively rigid Seattle Uplift (see map). 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. [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). 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. [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. Ongoing mapping is revealing more faults. 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. [80], In the crowded field of active or potentially active fault zones that have been discovered in the lower Snoqualmie Valley, the Cherry Creek fault zone is particularly notable because east of Duvall[81] it passes through a hotspot of active seismicity, including the 1996 '"`UNIQ--templatestyles-00000057-QINU`"'ML 5.3 Duvall earthquake. - Read More Expert Puts Turkey, Syria Quake into Perspective | FOX 13 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. 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. 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. [210] The zone between these two lines, reflecting changes in regional structure, seismicity, fault orientation, and possibly the underlying lithospheric structure, appears to be a major structural boundary in the Puget Lowland. to the north, past Lummi Island is contrary to the prevailing consensus that the DMF is not offset. Interpretation of the eastern part of the Tacoma Fault is not entirely settled. 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. Nurse Information Line at VA Puget Sound health care, 800-329-8387 x4. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). 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. Bubbles of methane rising from seafloor in Puget Sound Earthquake - Emergency Management | seattle.gov [11] Marine seismic reflection surveys on Puget Sound where it cuts across the various faults have provided cross-sectional views of the structure of some of these faults, and an intense, wide-area combined on-shore/off-shore study in 1998 (Seismic Hazards Investigation in Puget Sound, or SHIPS)[12] resulted in a three-dimensional model of much of the subsurface geometry. [187] Such a length would be comparable to the length of the Seattle or Tacoma faults, and capable of an earthquake of M 6.7. (1997) a slab of rock mainly basalts of the Crescent Formation about 20km thick is being pushed up a "master ramp" of deeper material; this forms the Seattle Uplift. It's due for another one,. 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. 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. Bubbles of methane rising from seafloor in Puget Sound