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. 1 - 10 of 77 American Spirit Cruise Reviews. 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. 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. [91] The relationship between these two fault zones is not entirely clear. The energy of the somewhat smaller Benioff earthquakes is likewise diluted over a relatively large area. [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). The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about magnitude 7 - an event that entered Native American oral legend. [38] These earthquakes probably caused tsunamis, and several nearby locations have evidence of tsunamis not correlated with other known quakes. A Seattle Fault quake could be as large as M7.5,160 but less than M7.0 is more probable. 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]. 48), along the edge of a formation known as the Southern Washington Cascades Conductor. [19] These terranes were covered by the basalts of the Crescent Formation (part of Siletzia). ISNS 2359 Earthquakes and Volcanoes Chapter 5 Questions - Quizlet [60] Such seismic hazards were a major issue in the siting of the plant, as it is tucked between two active strands, and the influent and effluent pipelines cross multiple zones of disturbed ground. Let's make your home safer The mapped surface traces are only 5km long, but LIDAR-derived imagery shows longer lineaments, with the traces cutting Holocene alluvial traces. The history and capabilities of the Frigid Creek Fault are not known. Strands of the east-striking Devils Mountain Fault cross the northern tip of Whidbey Island at Dugualla Bay and north side of Ault Field (Whidbey Island Naval Air Station). WASHINGTON: Methane Bubbles Up From Seafloor Near Seattle The map is from a 2007 report (click here to download) on seismic design categories in Washington. 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. [44] Another problem with the SWIF/RMFZ as CRBF is that a large westward step is required to connect from the RMFZ to the Saint Helens Zone (SHZ; see map), whereas the RMFZ turns easterly to align with the OWL. 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. PSE | Technical Resources for Construction - Puget Sound Energy 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: [51] Base map is hillshaded DEM derived from LiDAR data (pixel size 1.8 m) from Puget Sound LiDAR Consortium; illumination from azimuth 05, at 5 above the horizon; datum is NAD83, UTM zone 10N. Fault line puts Seattle at risk of 'The Big One' - UW Magazine 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. 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. Fault lines in the New Madrid seismic zone are being mapped, thanks in part to . [197] This anticline, or uplifted fold, and the narrower width of the northern part of the SWCC, reflects an episode of compression of this formation. (See, There is a preliminary report of aeromagnetic and gravity mapping placing the eastern edge of the Siletz terrane under Lake Washington. 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. These are usually fairly short, and not believed to be significantly seismogenic. There are other tsunami scenarios that are not accounted for in these maps, such as tsunamis caused by . [158] Vertical movement on these faults has created prominent scarps that have dammed Price Lake and (just north of Saddle Mountain) Lilliwaup Swamp. It's due for another one,. [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]. These mlanges may have been off-shore islands or seamounts that were caught between the Olympic terrane and the North American continent, and were pushed up (obducted) onto the latter. [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. [198], Does the SHZ extend north? 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. [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. [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. According to the Washington state Department of Natural Resources, more than 1,000 earthquakes happen in Washington state each year! 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. [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. The last major earthquake on the Seattle Fault occurred around 1,100 years ago, shifting the landscape in Puget Sound. [2] All this is at risk of earthquakes from three sources:[3]. They are also on-strike with a swarm of faults on the Columbia River, bracketing The Dalles. As all of these are thrust and reverse faults, they probably result from northeast directed regional compression. Nurse Recruiter at VA Puget Sound health care, 206-764-2487. Puget Sound, Washington has had: (M1.5 or greater) 0 earthquakes in the past 24 hours. The Pacific Northwest Seismic Network (PNSN) reported at least three earthquakes within the past few days. ISNS Ch 5 Flashcards | Quizlet ), 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". Bubbles of methane rising from seafloor in Puget Sound - Phys.org 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. 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 . The fault type is subducting. The Earthquake That Will Devastate the Pacific Northwest 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. 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 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. 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. Next to a 4-6 lines highways with 90db noise and cancerous pollution. 112 earthquakes in the past 365 days. $30 to $33 Hourly. [132], Scarps associated with Holocene uplift of the Tacoma fault have been traced westward to Prickett Lake (southwest of Belfair, see map). 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. ecc.kc@kingcounty.gov. 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. South of the OWL a definite eastern boundary has not been found, with some indications it is indefinite. 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. Some upper-crustal formations (such as the Western and Eastern Melange Belts, see, There is a general north or northeast directed compression within the Lowland causing folds, which eventually break to become, This page was last edited on 11 January 2023, at 17:28. This map shows the primary earthquake faults in the Puget Sound and other less prominent faults. [213] Seismicity sometimes occurs in zones, such as has been observed under Mercer Island, or from downtown Seattle towards Kirkland[214] but whether particular zones reflect undiscovered faults, or might be the source of damaging earthquakes, is generally unknown. Most of these "faults" are actually zones of complex faulting at the boundaries between sedimentary basins (synclines, "") and crustal uplifts (anticlines, ""). Puget Sound Lidar Consortium Finding faults scarp(n). Methane Plume Emissions Associated With Puget Sound Faults in the Cascadia Forearc. [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. PSLC--finding faults - University of Washington Puget Sound Energy transmission line project Energize Eastside. Active tectonics of the Seattle fault and central Puget sound The Straight Creek Fault is a major structure in the North Cascades, but has not been active for over 30 million years. 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. 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 Rainier, along the DDMFZ, and under Puget Sound between Olympia and approximately the Southern Whidbey Island Fault. One animation shows the expected path of a Puget Sound tsunami generated by a quake on the Seattle Fault. Tacoma's Gain is Seattle's Pain. [77] From a point just north of Carnation the eastern edge of the CCFZ (here it is about three-quarters of a mile wide) can be traced up Harris Creek, crossing the upper reach of Cherry Creek, eventually reaching the town of Sultan. 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. [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. Puget Sound Energy. Toll Free 1-800-523-5044. This section of the SWIF forms the southwestern side of the Everett Basin[48] (see map), which is notably aseismic in that essentially no shallow (less than 12km deep) earthquakes have occurred there, or on the section of the SWIF adjoining it, in the first 38 years of instrumental recording. Full-Time. 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).