fault lines in puget sound

[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]. Geologic map of southwestern Washington (GM-34). All this is explained by right-lateral strike-slip motion on the Straight Creek Fault, which initiated about 50 to 48 Ma (millions of years ago). . 3511 NE Second St. Renton, WA 98056. [87], Rattlesnake Mountain is a prominent NNW trending ridge just west of North Bend (about 25 miles east of Seattle). [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. 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. 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. [138] It arises from the contrast between the denser and more magnetic basalt of the Crescent Formation that has been uplifted to the east, and the glacial sediments that have filled the Dewatto basin to the west. In the wedge model of Pratt et al. Gonzalez: That Seattle Fault tsunami has been modeled by others. According to the recent seismological studies, the Seattle Fault is believed to be a zone of thrust or reverse faults that strikes through Seattle in the densely populated Puget Lowland of western Washington (Johnson et al., 1999). 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. [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. 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. 48), along the edge of a formation known as the Southern Washington Cascades Conductor. Initially it was not specified, and rather vaguely indicated to be west of Restoration Point (i.e., west of Puget Sound). "[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. Cheney also mapped the Lake Chaplain Fault, parallel and just east of the MVF, from Lake Chaplain to Granite Falls. The fault type is subducting. 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? Pratt et al. 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. "[50], The contrast of seismic velocities seen to the northwest is lacking in this section, suggesting that it is not the Coast RangeCascade contact. 5) Select plot type. In the angle between these is located the minor Lincoln Creek uplift, the Doty Hills, and, further west, an impressive chunk of Crescent basalt. Rainier, along the DDMFZ, and under Puget Sound between Olympia and approximately the Southern Whidbey Island Fault. [181] What is unknown is whether this was due to a great subduction earthquake, to the noted earthquake on the Seattle Fault about that time, or to an earthquake on a local fault (e.g., the Olympia structure); there is some evidence that there were two earthquakes over a short time period. Aeromagnetic surveys,[13] seismic tomography,[14] and other studies have also contributed to locating and understanding these faults. Nor does this uplift delineate any significant basin between it and the Devils Mountain Fault. Geologic map of northwestern Washington (GM-50). 39 earthquakes in the past 365 days. . [38] These earthquakes probably caused tsunamis, and several nearby locations have evidence of tsunamis not correlated with other known quakes. [104] Although there is no direct evidence for any major north-striking faults under Seattle, this prospect appears to be endorsed by the geological community.[105]. NW-striking black lines are right-lateral bedrock faults thought to be subsidiary to Dar- rington-Devils Mountain fault zone (Dragovich and DeOme, 2006). The DotySalzer Creek Fault does not fully fit the regional pattern of basins and uplifts bounded by faults described above. 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. [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 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. Not until 2001 was it identified as a fault zone,[12] and only in 2004 did trenching reveal Holocene activity. One study of seismic vulnerability of bridges in the Seattle Tacoma area[4] estimated that an M 7 earthquake on the Seattle or Tacoma faults would cause nearly as much damage as a M 9 subduction earthquake. But. Most of this thrust sheet consists of the Crescent Formation (corresponding to the Siletz River volcanics in Oregon and Metchosin Formation on Vancouver Island), a vast outpouring of volcanic basalt from the Eocene epoch (about 50 million years ago), with an origin variously attributed to a seamount chain, or continental margin rifting (see Siletzia). The Straight Creek Fault is a major structure in the North Cascades, but has not been active for over 30 million years. "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 . [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. 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. 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. 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. This structure is shown in the gravitational mapping of 1965, but without comment. 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. There is a general pattern where most of these faults partition a series of basins and uplifts, each about 20km wide. [51] This is because the Olympic terrane is moving (relative to North America) northeast; its continued clockwise rotation is akin to a giant wheel rolling up the western side of the North Cascade crystalline core. [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. Aeromagnetic anomaly maps (USGS OFR 99-514). This map of Puget Sound shows the location of the methane plumes as yellow and white circles. A 2001 study[148] using high-resolution seismic tomography questioned its existence. The earthquake scenario used in the modeling is a "very large, low-probability" magnitude 7.5 earthquake on the Seattle Fault, which runs east-west through Puget Sound and downtown Seattle.. Harold Tobin, a researcher at the University of Washington and director of the Pacific Northwest Seismic Network, says the fault line that caused earthquake that shook southern Turkey near the Turkish-Syrian border and killed more than 7,000 people is similar to the faults under Puget Sound. 4 earthquakes in the past 30 days. [106] There is an intriguing view from Stanley, Villaseor & Benz (1999) (see Fig. [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). The last major earthquake on the Seattle Fault occurred around 1,100 years ago, shifting the landscape in Puget Sound. 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. 2-5 Cruises Age 60s. ), 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". 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. According to the preeminent model, the "Puget Lowland thrust sheet hypothesis",[26] these faults, etc., occur within a sheet of crust about 14 to 20km deep that has separated from and is being thrust over deeper crustal blocks. [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. 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. 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. 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: [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. Faults running on the Snohomish County-Skagit County line and between Port Townsend and Whidbey Island point toward Vancouver Island. But today, after 131 years of statehood, residents of this region still don't know if they have a legal right to walk across a privately . A Lofall Fault has been reported on the basis of marine seismic reflection surveying,[216] but has not been confirmed by trenching. [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). Nurse Information Line at VA Puget Sound health care, 800-329-8387 x4. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault Calawah fault Barnes Creek The history and capabilities of the Frigid Creek Fault are not known. Posted: 12 days ago. It is not notably seismogenic. Western Washington lies over the Cascadia subduction zone, where the Juan de Fuca Plate is subducting towards the east (see diagram, right). San Juan Island hopping on the Puget Sound, WA. 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). [19] These terranes were covered by the basalts of the Crescent Formation (part of Siletzia). [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 map also shows potentially active faults from a separate 2014 report (click here to download). [40], The Southern Whidbey Island Fault (SWIF) is a significant terrane boundary manifested as an approximately four mile wide zone of complex transpressional faulting with at least three strands. [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". OLYMPIA, Wash. - A 9. [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. Whether the faulting continues eastward is not yet determined. 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 . South of the OWL a definite eastern boundary has not been found, with some indications it is indefinite. [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. The length of the Doty Fault is problematical: the report in 2000 gave it as 65km (40 miles), but without comment or citation. 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 . 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. 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. [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. Puget Sound Energy. [206] This line may also mark the northwestern boundary of the SWCC. [100], However, gravity and other data suggest that near the southern tip of Whidbey Island the Crescent Formation contact may turn away from the SWIF, and may even be reentrant under north Seattle,[101] forming the northwestern side of the Seattle Basin, and possibly connecting with the recently reported "Bremerton trend" of faulting running from the southern end of Hood Canal, through Sinclair Inlet (Bremerton), and across Puget Sound. The QFFDB, citing lack of consensus, ignores the eastern part. 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. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). 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. Discovery of faults has been greatly facilitated with the development of LIDAR, a technique that can generally penetrate forest canopy and vegetation to image the actual ground surface with an unprecedented accuracy of approximately one foot (30cm). 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. [5] The southern limit nearly matches the southern limit of the glaciation; possibly the seismicity reflects rebound of the upper crust after being stressed by the weight of the glacial ice. Mount Vernon Fault/Granite Falls FZ/Woods Creek, Rogers Belt (Mount Vernon Fault/Granite Falls Fault Zone), Saint Helens Zone and Western Rainier Zone, Quaternary fault and fold database (QFFDB), USGS QFFDB Fault #574, Devils Mountain Fault, USGS QFFDB Fault #571, Strawberry Point Fault, USGS QFFDB Fault #573, Utsalady Point Fault, Brightwater regional sewage treatment plant, USGS QFFDB Fault #572, Southern Whidbey Island Fault, USGS QFFDB Fault #575, Saddle Mountain Faults, "A Rifted Margin Origin for the Crescent Basalts and Related Rocks in the Northern Coast Range Volcanic Province, Washington and British Columbia", "Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington", "Volcanism, Isostatic Residual Gravity, and Regional Tectonic Setting of the Cascade Volcanic Province", "Findings on the southern Whidbey Island fault zone from aeromagnetic anomalies, lidar surveys, and trenching", "The Saddle Mountain Fault Deformation Zone, Olympic Peninsula, Washington: Western Boundary of the Seattle Uplift", "Connecting Crustal Faults and Tectonics from Puget Sound across the Cascade Range to the Yakima Fold and Thrust Belt, Washington: Evidence from New High-Resolution Aeromagnetic Data [Abstract GP232-02]", Eos, Transactions, American Geophysical Union, "The Cottage Lake Aeromagnetic Lineament: A possible onshore extension of the Southern Whidbey Island Fault, Washington", "Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data", 10.1130/0016-7606(2002)114<0169:LSASOT>2.0.CO;2, "High-pressure metamporphism and uplift of the Olympic subduction complex", 10.1130/0091-7613(1990)018<1252:HPMAUO>2.3.CO;2, "Interpretation of the Seattle Uplift, Washington, as a Passive-Roof Duplex", "Tectonic elements and evolution of northwest Washington", "Quaternary faulting on Dow Mountain, Mason County", "Major Cenozoic faults in the northern Puget Lowland of Washington", "High-Resolution Seismic Reflection Imaging of Growth Folding and Shallow Faults beneath the Southern Puget Lowland, Washington State", "LITHOPROBE southern Vancouver Island: Cenozoic subduction complex imaged by deep seismic reflections", "Geologic map of the Lilliwaup 7.5-minute quadrangle, Mason County, Washington", "Geologic map of the Holly 7.5-minute quadrangle, Jefferson, Kitsap, and Mason Counties, Washington", "Geologic map of the Eldon 7.5-minute quadrangle, Jefferson, Kitsap, and Mason Counties, Washington", "Geophysical Investigation of the Southern Puget Sound Area, Washington", "Geologic Map and Interpreted Geologic History of the Bow and Alger 7.5-minute Quadrangles, Western Skagit County, Washington", "Geologic Map of Washington Northwest Quadrant", "Geologic map of the Oak Harbor, Crescent Harbor, and part of the Smith Island 7.5-minute quadrangles, Island County", "Geologic map of the McMurray 7.5-minute Quadrangle, Skagit and Snohomish Counties, Washington, with a Discussion of the Evidence for Holocene Activity on the DarringtonDevils Mountain Fault Zone", "Geologic map of the Fall City 7.5-minute quadrangle, King County, Washington", "Geologic map of the North Bend 7.5-minute quadrangle, King County, Washington, with a discussion of major faults, folds, and basins in the map area", "Geologic Map of the Snoqualmie 7.5-Minute Quadrangle, King County, Washington", "Geologic map of the Carnation 7.5-minute quadrangle, King County, Washington", "Supplement to the geologic map of the Carnation 7.5-minute quadrangle, King County, Washington Geochronologic, geochemical, point count, geophysical, earthquake, fault, and neotectonic data", "Geologic map of the Monroe 7.5-minute quadrangle, King County, Washington", "Geologic map of the Lake Joy 7.5-minute quadrangle, King County, Washington", "Geologic map of the Sultan 7.5-minute quadrangle, Snohomish and King Counties, Washington", "Geologic Map of the Lake Chaplain 7.5-minute Quadrangle, Snohomish County, Washington", "Geologic map of the Lake Roesiger 7.5-minute quadrangle, Snohomish County, Washington", "Geologic Map of the Granite Falls 7.5-minute Quadrangle, Snohomish County, Washington", "Imaging Crustal Structure in Southwestern Washington With Small Magnetometer Arrays", "Geology of the Mount St. Helens Area: Record of Discontinuous Volcanic and Plutonic Activity in the Cascade Arc of Southern Washington", "Geophysical constraints on Washington convergent margin structure", "Aeromagnetic map compilation: procedures for merging and an example from Washington", "Something old, something new, something borrowed, something blue - a new perspective on seismic hazards in Washington using aeromagnetic data", "Constraints on surface deformation in the Seattle, WA, urban corridor from satellite radar interferometry time-series analysis", "Crustal Structure and Earthquake Hazards of the Subduction Zone in Southwestern British Columbia and Western Washington", "Late Mesozoic or Early Tertiary Melanges in the Western Cascades of Washington", "Seismotectonic map of the Puget Sound region, Washington", "Distribution of late Cenozoic volcanic vents in the Cascade Range: Volcanic arc segmentation and regional tectonic considerations", "Geologic map of the Wildcat Lake 7.5' quadrangle, Kitsap and Mason Counties, Washington", "Fault scarp detection beneath dense vegetation cover: airborne LIDAR mapping of the Seattle Fault Zone, Bainbridge Island, Washington State", 10.1130/1052-5173(2003)13<0004:HLTOTP>2.0.CO;2, "Structural variation along the Devil's Mountain fault zone, northwestern Washington", 10.1130/0091-7613(1980)8<15:SOTCVC>2.0.CO;2, "Fault number 572, Southern Whidbey Island Fault", "Active shortening of the Cascadia forearc and implications for seismic hazards of the Puget Lowland", "Active tectonics of the Seattle fault and central Puget Sound, Washington Implications for earthquake hazards", 10.1130/0016-7606(1999)111<1042:ATOTSF>2.3.CO;2, "Evidence for Late Holocene Earthquakes on the Utsalady Point Fault, Northern Puget Lowland, Washington", 10.1130/0091-7613(1994)022<0071:OAEOTS>2.3.CO;2, "The southern Whidbey Island fault An active structure in the Puget Lowland, Washington", 10.1130/0016-7606(1996)108<0334:TSWIFA>2.3.CO;2, "Late Holocene displacement on the Southern Whidbey Island fault zone, northern Puget lowland", "The Tahuya Lineament: Southwestern Extension of the Seattle Fault?