fault lines in puget sound fault lines in puget sound

[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. 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. [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. Aeromagnetic surveys,[13] seismic tomography,[14] and other studies have also contributed to locating and understanding these faults. But their significance to the Puget Sound area is unknown. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). San Juan Island hopping on the Puget Sound, WA. But the western segment the Devils Mountain Fault has left-lateral movement. In the wedge model of Pratt et al. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. 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. For information about the Energize Eastside project, . 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. Nor does this uplift delineate any significant basin between it and the Devils Mountain Fault. [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. (Their model of the Black Hills Uplift is analogous with their "wedge" model of the Seattle Uplift, discussed above, but in the opposite direction. 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. 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. to the north, past Lummi Island is contrary to the prevailing consensus that the DMF is not offset. 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. King County Emergency Management. 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. 2-5 Cruises Age 60s. This map shows the primary earthquake faults in the Puget Sound and other less prominent faults. 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. Energy builds up as elastic strain in rocks. These are usually fairly short, and not believed to be significantly seismogenic. 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 [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. 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. 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. That wave is quite severe, quite high. Please follow the steps below: . Olympia VA Clinic at VA Puget Sound health care, 253-583-2621 Puget Sound Energy. Kinematic analysis suggests that if shortening (compression) in the Puget Lowland is directed to the northeast (i.e., parallel to Hood Canal and the Saddle Mountain deformation zone) and thus oblique to the Dewatto lineament, it should be subject to both strike-slip and dip-slip forces, implying a fault. This is the Puget Lowland. ), 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. [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. 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. Its capable magnitude is a megathrust quake exceeding 9.0. 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. Recent EQ List 6) Click "Plot" Draw. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates . The Devils Mountain Fault separates two similar but distinctive ensembles of Mesozoic (pre-Tertiary, before the dinosaurs died) or older rock. [215] 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). [216], An Everett Fault, running east-northeast along the bluffs between Mukilteo and Everett that is, east of the SWIF and at the southern edge of the Everett Basin has been claimed, but this does not appear to have been corroborated.[217]. Other similar lineaments (such as from Astoria to Glacier Peak) align with various topographical features and changes in fault orientation. Interpretation of the eastern part of the Tacoma Fault is not entirely settled. The Seattle uplift, and possibly the Black Hills uplift, consist of Crescent Formation basalt that was exposed when it was forced up a ramp of some kind. 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]. Olympic Peninsula, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. [78] It is projected to extend past Lake Chaplain, and perhaps to the east end of Mount Pilchuck. [92] This is where the SWIF encounters the edge of the Western and Eastern Melange Belts (remnants of a mid-Cretaceous subduction zone[93]); the RMFZ is where the Seattle Uplift is being forced against the Western Melange belt[94], To the north the Melange Belt is manifested as the Rogers Belt, a zone of low-amplitude folding stretching from Monroe to Mount Vernon; the apparent western edge of this zone is on-strike with the RMFZ. 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. This formation, up to 15km thick, is largely buried (from one to ten kilometers deep), and known mainly by magnetotellurics and other geophysical methods. 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. [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]. The Bellingham BayChaplain fault zone was first mapped by Cheney in 1976 as running from near Chaplain Lake (north of Sultan) NNW past Bellingham Bay. 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 map also shows potentially active faults from a separate 2014 report (click here to download). 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. [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). Cheney also mapped the Lake Chaplain Fault, parallel and just east of the MVF, from Lake Chaplain to Granite Falls. Next to a 4-6 lines highways with 90db noise and cancerous pollution. [219] Various other faults in the North Cascades are older (being offset by the Straight Creek Fault) and are unrelated to the faults in Puget Sound. While the great subduction events release much energy (around magnitude 9), that energy is spread over a large area, and largely centered near the coast. 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. 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. Those Hollywood depictions of a. 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 . 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. This bend has distorted the subducting slab into an arch that has lifted the Olympic Mountains and prevented them from subducting. . Plot Type: X-Section Depth Cumulative # Mag-Time. [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. 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. [122] This trend extends further north where the Pleasant Harbor lineament appears to terminate other westward extensions of the SFZ. A Coast Range Boundary Fault (CRBF, discussed above) was inferred on the basis of differences in the basement rock to the west and east of Puget Sound (the Crescent FormationCascadia core contact), and arbitrarily mapped at various locations including Lake Washington; north of the OWL this is now generally identified, with the Southern Whidbey Island Fault. [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. 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. 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. "Most often, when we think of tsunamis, we think of our outer coast and communities along the Pacific Ocean. [66] This is located on a topographical lineament that aligns with Mount Vernon to the north, and, to the south, the city of Granite Falls and Lake Chaplain (just north of Sultan). 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. The magnitude-4.0 earthquake that rattled people awake across the Puget Sound region last Wednesday probably struck on the western edge of the Seattle Fault, according to geologists. Glacially deposited and shaped fill covers most of the lower elevations of Puget Sound. Puget Sound and San Juan islands. 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. [200], Mount St. Helens and Mount Rainier are located where their associated fault zones make a bend (see map, above).[201](Mt. Clearance, service lines and meter locations. The Cascadia Fault is 620 miles long off the coast of Washington and British Columbia. The answer is still unresolved. 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). [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. Not until 2001 was it identified as a fault zone,[12] and only in 2004 did trenching reveal Holocene activity. Marine technician Sony Brugger, right, retrieves underwater sampling equipment during a December 2020 research cruise aboard the RV Rachel Carson. [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). [209] Between the Cherry Creek and parallel Tokul Creek faults is a contact between formations of the Western Melange Belt. Study of surface deformation suggests possible unmapped faults near Federal Way, running between Sumner and Steilacoom, and south of Renton.[223]. 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. Rainier, along the DDMFZ, and under Puget Sound between Olympia and approximately the Southern Whidbey Island Fault. Combined with continued aggressive electric conservation efforts, Energize . 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. 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. Aeromagnetic anomaly maps (USGS OFR 99-514). The structure of the Seattle Fault zone still have great uncertainty and there exist a number of interpretations. 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. 48), along the edge of a formation known as the Southern Washington Cascades Conductor. 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. 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. 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. There is evidence that the Tacoma Fault connects with the White River River Fault (WRF) via the EPZ and Federal Way, under the Muckleshoot Basin (see map),[137] and thence to the Naches River Fault. [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. It is coincident with, and possibly a result of uplift on, the Rattlesnake Mountain Fault Zone (RMFZ), a band of at least eleven faults that show both dip-slip (vertical) and right-lateral strike-slip motion. There's a one-in-10 chance that the next . But. However, there are indications that the fault is segmented, which might limit rupturing and earthquake magnitude.[36]. 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. [61], North of Everett is an area of parallel ridges and stream drainages oriented approximately NW-SE, evident even on non-geological maps. While these models vary in some details, both indicate that the Seattle Fault itself is capable of a magnitude 7.5 earthquake. [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. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. 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. [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. There are some interesting relationships here. 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). . Accommodation of strain (displacement) between the Seattle Fault and the Saddle Mountain deformation zone is likely distributed across the more pliable sediments of the Dewatto Basin; this, and the greater depth to the Crescent Formation, may account for the subdued expression of the Seattle Fault west of Green Mountain. Black squares are urban sewer outfalls, which don't match the bubble plumes' locations. 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. 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). Energize Eastside project is building a new substation and upgrading approximately 16 miles of existing transmission lines from Redmond to Renton. The fault type is subducting. [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. [114] An early view was that "the Seattle Fault appears to be truncated by the Hood Canal fault and does not extend into the Olympic Mountains". Tobin says offshore faults tend to cause bigger earthquakes and are a larger tsunami risk. 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. [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. [145] This is conformable with some regional tectonic interpretations[146] that put a major terrane boundary between the Olympics and the Puget Lowland, and imply a connection (either via the Discovery Bay Fault, or closer to Port Townsend) to the various faults in the Strait of Juan de Fuca. The DotySalzer Creek Fault does not fully fit the regional pattern of basins and uplifts bounded by faults described above. This map is useful in showing the location and approximate length of faults but does not provide the impact an earthquake from a fault could have on the area surrounding. 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. (1997), while observing the "remarkable straight boundaries that we interpret as evidence of structural control",[171] refrained from calling this structure a fault. 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. Fault lines in the New Madrid seismic zone are being mapped, thanks in part to . 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