While these models vary in some details, both indicate that the Seattle Fault itself is capable of a magnitude 7.5 earthquake. 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. Though a 2012 study[149] interpreted a different variety of tomographic data as showing the Hood Canal fault, other mapping has "found no convincing evidence for the existence of this fault",[150] considers it doubtful,[151] depicted it "with low level of confidence",[152] or omits it entirely. Most of these "faults" are actually zones of complex faulting at the boundaries between sedimentary basins (synclines, "") and crustal uplifts (anticlines, ""). This is supported by geologically recent scarps and other signs of active faulting on the Saddle Mountain faults, and also discovery of a geophysical lineament running through Pleasant Harbor (south of Brinnon) that appears to truncate strands of the Seattle Fault. E.g., HH mlange rock has been found in Manastash Ridge, 110km to the south (look for the small sliver of purple near the bottom of the diagram). 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]. [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. This map shows areas of seismic risk from high (red) to low (grayish-green). The Seattle Fault crosses east-west through Puget Sound and downtown Seattle. 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. The apparent gap north of Riffe Lake is possibly due to obscuration by volcanic deposits of the Northcraft Formation. 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. "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 . [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. But. Offsets in the eastwest oriented Monroe Fault (south side of the Skykomish River), earthquake focal mechanisms, and kinematic indications show that the CCFZ is a left-lateral strike-slip fault, possibly with some oblique motion (up on the eastern side). Puget Sound and San Juan islands. It's the other counties in the Puget . 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. [98] This turns and runs just south of Victoria, nearly in-line with the SWIF. [178] Alternately, the OS appears to coincide with a gravitational boundary in the upper crust that has been mapped striking southeast to The Dalles on the Columbia River,[179] where there is a swarm of similarly striking faults. [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". 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. Cluster of earthquakes in Puget Sound considered 'normal', earthquake researchers say. In the angle between these is located the minor Lincoln Creek uplift, the Doty Hills, and, further west, an impressive chunk of Crescent basalt. The energy of the somewhat smaller Benioff earthquakes is likewise diluted over a relatively large area. Energy builds up as elastic strain in rocks. [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. [82] [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". While there is a bit of uplifted pre-Tertiary rock between the SPF and UPF, this does not truly fit the uplift and basin pattern described above because of the small scale (2km wide rather than around 20), and because the uplift here is entirely like a wedge being popped out between two nearly vertical faults, rather than being forced over a ramp such as is involved with the Seattle and Tacoma faults. [29] This prospect is especially intriguing as a possible explanation of a cluster of seismic events around 1100 years ago.[30]. 39 earthquakes in the past 365 days. These bends are located where they intercept a "subtle geological structure"[202] of "possible fundamental importance",[203] a NNE striking zone (line "A" on the map) of various faults (including the Tokul Creek Fault NNE of Snoqualmie) and early-Miocene (about 24 Ma) volcanic vents and intrusive bodies (plutons and batholiths) extending from Portland to Glacier Peak;[204] it also marks the change in regional fault orientation noted above. [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. 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 map is from a 2007 report (click here to download) on seismic design categories in Washington. However, the SWCC is relatively shallow (no more than 15 km deep), and likely is draped over pre-Tertiary bedrock. Read More. The fault type is subducting. [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. 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 These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) 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. These faults also form the north and south boundaries of uplifted pre-Tertiary rock, suggesting that the faults come together at a lower level, much like one model of the Seattle and Tacoma faults, but at a smaller scale. [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). 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. Washington State Earthquake Hazard Map Seattle Fault Lines 552 - Hood Canal fault zone (Class B) 570 - Seattle fault zone 572 - Southern Whidbey Island fault zone 575 - Saddle Mountain faults 581 - Tacoma fault zone USA Earthquake Hazard Map Source: United States Geological Survey Ready to retrofit? [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. 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. The mapped surface traces are only 5km long, but LIDAR-derived imagery shows longer lineaments, with the traces cutting Holocene alluvial traces. 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. The last major earthquake on the Seattle Fault occurred around 1,100 years ago, shifting the landscape in Puget Sound. ecc.kc@kingcounty.gov. Simply put, the basement rock on the west side of Puget Sound does not match the basement rock on the east side. Movement on the southern segment of the DDMFZ that converges with the SCF the Darrington Fault was, as on the SCF itself, right-lateral. However, most seismic activity is not associated with any known fault. Also intersecting at Mount St. Helens is a NE (045) trending line (red) of Pleistocene (about 4 Ma) plug domes and a topographic lineament (followed in part by Highway 12). [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. Read More. Both of these are dip-slip (vertical) faults; the block between them has been popped up by compressive forces. But their significance to the Puget Sound area is unknown. There is a general pattern where most of these faults partition a series of basins and uplifts, each about 20km wide. Somewhere between Puget Sound and Cascades foothills these two geological provinces come into contact. Glacially deposited and shaped fill covers most of the lower elevations of Puget Sound. The true length of the UPF is likely twice as long, as it forms the southern margin of an aeromagnetic high that extends another 25km to the southeast. Ongoing mapping is revealing more faults. Earthquakes occur nearly every day in Washington. These include the: Southern Whidbey Island Fault (SWIF) Seattle Fault Devils Mountain Fault Strawberry Point fault Utsalady Point fault Calawah fault Barnes Creek 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 . This may explain why the Seattle and Tacoma faults seem to have ruptured at nearly the same time.[127]. [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]. The study was. A Cascadia event could cause dangerous currents in Puget Sound, reaching speeds up to 9 knots in the Agate Passage north of Bainbridge Island and 6 knots off of Discovery Park in Seattle. [78] It is projected to extend past Lake Chaplain, and perhaps to the east end of Mount Pilchuck. 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 . Conjugate faults are secondary faults that branch off from opposite sides of a strike-slip fault at approximately the same angle. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. Document name Date Description Additional versions; 2809: 4/1/2021: . 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. [67] However, subsequent mapping shows that the Woods Creek Fault (WCF), a four-mile wide strip of oblique-slip and strike-slip faults just to the west and passing directly under Sultan, appears to be the more significant fault, and better aligned with Mount Vernon. Puget Sound Lidar Consortium Finding faults scarp(n). 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. 206-296-3830. Newport Inglewood Rose Canyon Fault Zone. This is just after the terrane carrying the Olympic Mountains came into contact with the North American continent. 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. [71], These faults cut through the Western Mlange Belt (WMB; blue area in map), exposed from North Bend (on Interstate 90) to Mount Vernon. Yet the former is only the first of at least six more parallel southeast striking faults, which do cross the Salzer Creek Fault. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. Arcos' work suggests. 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. It is not notably seismogenic. 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. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates . Rainier is offset because the faults are deep and the conduits do not rise quite vertically.) Pratt et al. [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. 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. 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. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. PNSN staff will continue to develop this section of the web site but to find more good information now, visit these resources: NW-striking black lines are right-lateral bedrock faults thought to be subsidiary to Dar- rington-Devils Mountain fault zone (Dragovich and DeOme, 2006). 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. [37] Trenching on the UPF (at a scarp identified by LIDAR) shows at least one and probably two Holocene earthquakes of magnitude 6.7 or more, the most recent one between AD 1550 to 1850, and possibly triggered by the 1700 Cascadia earthquake. The SWCC appears to be Tertiary marine sediments, not the pre-Tertiary metamorphic rock of the Cascades province; this would seem to make it part of the Coast Range province, with the Coast RangeCascade contact further east. 10+ Cruises Age 2020s. Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc CC BY 4.0 Authors: H. Paul Johnson University of Washington Seattle S. G. Merle National Oceanic and. This map of Puget Sound shows the location of the methane plumes as yellow and white circles. On the north is the HelenaHaystack mlange (HH mlange, purple in the diagram at right), on the south the Western and Eastern mlange belts (WEMB, blue). They run . When the applied stresses become overpowering, the rocks at the fault rupture. 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. For information about the Energize Eastside project, . 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. TTY Relay 711. 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. 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 . 4) Drag square on line to include events to plot. The QFFDB, citing lack of consensus, ignores the eastern part. [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). This is an important observation because the Strawberry Point, Utsalady Point, Southern Whidbey Island, and various other unnamed faults lying between the DDMFZ and the OWL all of which converge at the western end of the DDMFZ seem to be intermediate versions of the DDMFZ.[34]. (Their model of the Black Hills Uplift is analogous with their "wedge" model of the Seattle Uplift, discussed above, but in the opposite direction. [203] This line is the southernmost of a band of NE trending faults and topographical lineaments that extend from the Oregon coast into the North Cascades. 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. New gravity data provide information [abstract]", "Fault locking, block rotation and crustal deformation in the Pacific Northwest", "The Everett fault: a newly discovered late Quaternary fault in north-central Puget Sound, Washington [abstract]", "Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington", "Field and laboratory data from an earthquake history study of scarps in the hanging wall of the Tacoma fault, Mason and Pierce Counties, Washington", "Three-dimensional velocity structure of Siletzia and other accreted terranes in the Cascadia forearc of Washington", "Geologic map of the Skokomish Valley and Union 7.5-minute quadrangles, Mason County, Washington", "Supplement to Geologic Maps of the Lilliwaup, Skokomish Valley, and Union 7.5-minute Quadrangles, Mason County, Washington Geologic Setting and Development Around the Great Bend of Hood Canal", "Geologic map of the Hoodsport 7.5-minute quadrangle, Mason County, Washington", "Geologic map of the Brinnon 7.5-minute quadrangle, Jefferson and Kitsap Counties, Washington", "Geologic map of the Seabeck and Poulsbo 7.5-minute quadrangles, Kitsap and Jefferson Counties, Washington", "Evidence for earthquake-induced subsidence ~1100 yr ago in coastal marshes of southern Puget Sound, Washington", 10.1130/0016-7606(2001)113<1299:EFEISA>2.0.CO;2, "Holocene fault scarps and shallow magnetic anomalies along the Southern Whidbey Island Fault Zone near Woodinville, Washington", "Finding concealed active faults: Extending the southern Whidbey Island fault across the Puget Lowland, Washington", "Holocene fault scarps near Tacoma, Washington, USA", "The Catfish Lake Scarp, Allyn, Washington: Preliminary Field Data and Implications for Earthquake Hazards posed by the Tacoma Fault", "Seismic Amplification within the Seattle Basin, Washington State: Insights from SHIPS Seismic Tomography Experiments", "Tectonics and Conductivity Structures in the Southern Washington Cascades", "Analysis of Deep Seismic Reflection and Other Data From the Southern Washington Cascades", "Tectonics and Seismicity of the Southern Washington Cascade Range", "Subduction zone and crustal dynamics of western Washington: A tectonic model for earthquake hazards evaluation", 10.1130/0016-7606(1994)106<0217:lmapet>2.3.co;2, "Geologic map of the Snoqualmie Pass 60 minute by 30 minute quadrangle, Washington", "Subsurface Geometry and Evolution of the Seattle Fault Zone and the Seattle Basin, Washington", "Rupture models for the A.D. 900930 Seattle fault earthquake from uplifted shorelines", "Stratigraphy of Eocene rocks in a part of King County, Washington", "Geologic map of Washington Southwest Quadrant", "Geologic Map of the East Olympia 7.5-minute Quadrangle, Thurston County, Washington", "Field data for a trench on the Canyon River fault, southeast Olympic Mountains, Washington", "Crustal Extension at Mount St. Helens, Washington", "Final Technical Report: Two Post-Glavial Earthquakes on the Saddle Mountain West Fault, southeastern Olympic Peninsula, Washington", "Earthquake scenario and probabilistic ground shaking maps for the Portland, Oregon, metropolitan area", "Bedrock Geologic Map of the Seattle 30' by 60' Quadrangle, Washington", Preliminary Atlas of Active Shallow Tectonic Deformation in the Puget Lowland, Washington (USGS Open-File Report 2010-1149). Marine technician Sony Brugger, right, retrieves underwater sampling equipment during a December 2020 research cruise aboard the RV Rachel Carson. - Read More Expert Puts Turkey, Syria Quake into Perspective | FOX 13 How the CRBF might run north of Seattle (specifically, north of the OWL, which Seattle straddles) is unknown, and even questioned, as there is no direct evidence of such a fault. 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. Western Washington lies over the Cascadia subduction zone, where the Juan de Fuca Plate is subducting towards the east (see diagram, right). A different mountain and fault zone of the same name are located near Pasco; see QFFDB Fault #565), The southern end of Rattlesnake Mountain is truncated at the OlympicWallowa Lineament (OWL), and the faults turn easterly to merge with the OWL. [191] How they might be connected is unknown. East of Puget Sound the basement of the Cascades province is various pre-Tertiary (older than 65 Ma) metamorphic rock.