fault lines in puget sound

Very little is known about the structure of the deep crust (below about 30km or 19 miles), though this and other seismic tomography studies (such as Ramachandran 2001) provide tantalizing glimpses. At Darrington it is seen to connect with the Darrington Fault, which runs nearly south 110km to converge with the Straight Creek Fault (SCF), and then to turn near Easton to align with the OlympicWallowa Lineament; together these are known as the DarringtonDevils Mountain Fault Zone (DDMFZ). 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. But their significance to the Puget Sound area is unknown. 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. [102] Or the Crescent margin may simply (and quietly) just run south-southeast under Seattle to the WRZ. [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. Marine technician Sony Brugger, right, retrieves underwater sampling equipment during a December 2020 research cruise aboard the RV Rachel Carson. This is the Puget Lowland. [141] (Originally named the Tahuya Fault. Fault line puts Seattle at risk of 'The Big One' - UW Magazine The Puget Sound faults under the heavily populated Puget Sound region (Puget Lowland) of Washington state form a regional complex of interrelated seismogenic (earthquake-causing) geologic faults. 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. Although Washington State's Puget Sound has been shaken every few decades, damage in the region's largest cities, including Seattle, Tacoma and Olympia, has only ever been modest. [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". "[50], The contrast of seismic velocities seen to the northwest is lacking in this section, suggesting that it is not the Coast RangeCascade contact. [143] Such interconnection also suggests a capability for larger earthquakes (> M7 for the Seattle Fault); the amount of increased risk is unknown.[144]. Earthquake - Emergency Management | seattle.gov A Massive Earthquake Is Coming to CascadiaAnd It Can't Be Stopped Other faults to the south and southeast the Frigid Creek Fault and (to the west) Canyon River Fault suggest an extended zone of faulting at least 45km long. The 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. 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. [71], These faults cut through the Western Mlange Belt (WMB; blue area in map), exposed from North Bend (on Interstate 90) to Mount Vernon. 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. It is of interest here because the various strands of the Seattle Fault change orientation where they appear to cross the OWL,[20] and various other features, such as the Rosedale monocline and Olympia structure, and a great many local topographical features, have parallel alignments. This map of Puget Sound shows the location of the methane plumes (yellow and white circles) detected along the ship's path (purple). Scientists Search for New Faults in Puget Sound 1 - 10 of 77 American Spirit Cruise Reviews. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. 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). 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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? [73] The presence of detritus from the Idaho Batholith[72] indicates a former location closer to southern Idaho. 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. 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. [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. [42] Marine seismic reflection surveys show it striking northwest across the eastern end of the Strait of Juan de Fuca. Recent EQ List 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. 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. [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. Black lines show the South Whidbey Island Fault Zone, the Seattle Fault Zone and the Tacoma Fault Zone. [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. This formation, up to 15km thick, is largely buried (from one to ten kilometers deep), and known mainly by magnetotellurics and other geophysical methods. 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. Seattle Earthquakes, Types of Quakes & Fault Lines - TripSavvy [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. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. [207] North of the RMFZ it follows a topographical lineament that can be traced to Rockport (on Hwy. [115] This seems reasonable enough, as Hood Canal is a prominent physiographic boundary between the Olympic Mountains and Puget Lowlands, and believed to be the location of a major fault. Crustal Faults | Pacific Northwest Seismic Network [125] While some coherency is developing, the story is not complete: identified faults do not yet account for much of the region's seismicity. The Earthquake That Will Devastate the Pacific Northwest https://en.wikipedia.org/w/index.php?title=Puget_Sound_faults&oldid=1132982136, Creative Commons Attribution-ShareAlike License 3.0, A great subduction earthquake, such as the. Over 7,000 people are dead after a magnitude 7.8 earthquake shook southern Turkey, near the Turkish-Syrian border. Although the largely unstudied White River Fault (WRF) appears to lie just outside the Puget Lowland, it may actually connect under the Muckleshoot Basin to the East Passage Zone and the Tacoma Fault (map). Mapping from the Pacific Northwest Seismic Network shows that the bulk of the earthquakes in western Washington are concentrated in four places: in two narrow zones under Mt. Geochemistry, Geophysics, Geosystems , 2021; 23 (1) DOI: 10.1029/2021GC010211 Cite This Page : San Juan Island hopping on the Puget Sound, WA. Methane Plume Emissions Associated With Puget Sound Faults in the On the other hand, the contrasting character of the east-striking and southeast-striking segments is unsettling, and the change of direction somewhat difficult to reconcile with the observed fault traces. 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. 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 is the Dewatto lineament, believed to result from an east-dipping low-angle thrust fault where the western flank of the Seattle Uplift has been pushed into the northwestern corner of the Tacoma Basin. 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. [28] Faults and folds may develop where the thrust sheet is being bent, or where the leading edge is thrust over softer, weaker sedimentary deposits, and breaks off and slumps. Bubbles of methane rising from seafloor in Puget Sound 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. OLYMPIA, Wash. - A 9. Subsidence dated to between AD 1445 and 1655 has been reported in Mud Bay (just west of Olympia). "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 . American Seattle Cruise Reviews - Cruise Critic The fault type is subducting. [98] This turns and runs just south of Victoria, nearly in-line with the SWIF. [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). Observing these topographical features, some parallel gravity gradients, and a "very active zone of minor seismicity", William Rogers inferred in 1970 a "fault or other major structural feature".[64]. [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". On the eastern side, where the SWCC is believed to be in contact with pre-Tertiary terranes accreted to the North American craton, matters are different. 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. News Media at VA Puget Sound health care, 206-764-2435, 206-764-2317. [69] The principal zone of faulting extends from the Woods Creek Fault to the Granite Falls Fault Zone (GFFZ), slightly offset from the WCF and running under the town of Granite Falls. - Read More Expert Puts Turkey, Syria Quake into Perspective | FOX 13 Site Info - Earth and Space Sciences - University of Washington (A) Map of the Seattle fault zone (SFZ) in the central Puget Sound [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. On the east, the Devils Mountain Fault connects with the south striking Darrington Fault (not shown) which runs to the OWL, and the Southern Whidbey Island Fault extends via the Rattlesnake Mountain Fault Zone (dashed line) to the OWL. In some places, such as along the South Fork of the Stillaguamish River between Arlington and Granite Falls, there are also contrasting geological contacts. [78] It is projected to extend past Lake Chaplain, and perhaps to the east end of Mount Pilchuck. [82] These include (from north to south, see map) the: Devils Mountain Fault Strawberry Point and Utsalady Point faults Southern Whidbey Island Fault (SWIF) [46] Seismic tomography studies show that this portion of the SWIF marks a strong contrast of seismic velocities, such as is expected of Crescent Formation basalts in contact with the metamorphic basement rocks of the Cascades geologic province to the east. [154] In this view Hood Canal is only a syncline (dip) between the Olympic Mountains and the Puget Lowland, and such faults as have been found there are local and discontinuous, ancillary to the main zone of faulting to the west. [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. [198], Does the SHZ extend north? Seattle Fault Bigger Quake Threat Than Thought | Live Science American Spirit Cruise Reviews - Cruise Critic And since those models for the Seattle Fault were published, there've actually been many more Puget Sound faults discovered. Saint Helens and Mt. [153] For these reasons this is now a questioned fault, and is indicated on the map as a dashed line. 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? Nor does this uplift delineate any significant basin between it and the Devils Mountain Fault. See Snavely et al. Black lines show the South Whidbey Island Fault Zone, the . Puget Sound Lidar Consortium Finding faults scarp(n). [96] As the juxtaposition of various disparate tectonic structures in northwest Washington requires significant strike-slip movement, it is further expected that this contact will be a major fault.[97]. Toll Free 1-800-523-5044. 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. [58], Paleoseismological studies of the SWIF are scant. 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. 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). North Olympic Peninsula VA Clinic at VA Puget Sound health care, 360-565-7420. A new view is developing that the regional tectonic boundary is not under Hood Canal, but just to the west, involving the Saddle Mountain fault zone (discussed below) and associated faults. [132], Scarps associated with Holocene uplift of the Tacoma fault have been traced westward to Prickett Lake (southwest of Belfair, see map). 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. 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 . 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). [74], Early Eocene igneous units in the area appear to be part of a 49- to 44- Ma magmatic belt that appeared just after the arrival of Siletzia, and possibly associated with that event. 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 uplift and basin pattern is continued to the west and southwest by the Grays Harbor Basin, Willapa Hills Uplift, and Astoria Basin,[25] but it is not known if these are bounded by faults in the same manner as in the Puget Sound region. [123] Other studies have faults extending NW or WNW from the SF towards Dabob Bay;[124] these are now recognized as part of the Dabob Bay fault zone. [129] The western part is an active eastwest striking north dipping reverse fault that separates the Seattle Uplift and the Tacoma Basin, with approximately 30 miles (50km) of identified surface rupture. The 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. [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). 1958 and Geologic Map GM-34 for details.). Whether the faulting continues eastward is not yet determined. It appears that the Seattle Uplift is acting as a rigid block, with the Tacoma, Dewatto, and Seattle faults being the southern, western, and northern faces. [9] Not until 1992 was the first of the lowland faults, the Seattle Fault, confirmed to be an actual fault with Holocene activity, and the barest minimum of its history established.[10]. It may also be the original location of the DarringtonDevils Mountain Fault (the dashed line "X" at the top of the following map). [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]. 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. A recent (2009) analysis of aeromagnetic data[159] suggests that it extends at least 35km, from the latitude of the Seattle Fault (the Hamma Hamma River) to about 6km south of Lake Cushman. Those Hollywood depictions of a. Hood Canal marks an abrupt change of physiography between the Puget Lowland and the Olympic Mountains to the west. [106] There is an intriguing view from Stanley, Villaseor & Benz (1999) (see Fig. PSE | Technical Resources for Construction - Puget Sound Energy This map of Puget Sound shows the location of the methane plumes as yellow and white circles. Analyze Instructions: Close. [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. Tsunami waves as high as 42 feet could crash into Seattle within [76], The Cherry Creek fault zone (CCFZ) was discovered in 2010 while mapping the area at the north end of the Rattlesnake Mountain fault zone (RMFZ). [2] All this is at risk of earthquakes from three sources:[3]. The question of where on Puget Sound the line would ultimately end was intentionally left open, and the region's fledgling cities began competing furiously for the good fortune of a major railroad terminus. Puget Sound Energy Maps and Records Non-Disclosure Agreement: (NDA ONLY) ko ru zh es vi hi: PSE Map Request Form and Non-Disclosure Agreement: 07/29/2022: [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). Active tectonics of the Seattle fault and central Puget sound