DOCSLIB.ORG

South Puget Sound Earthquake (Pre)History by Timothy J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

South Puget Sound Earthquake (pre)History by Timothy J. Walsh Washington Department of Natural Resources Division of Geology and Earth Resources P. O. Box 47007, Olympia, WA 98504-7007 Photo by Bill Shilts Geologic Hazards • Landslides • Earthquakes • Tsunamis Landslides that have caused significant damage in Washington are generally deep-seated and slow moving or shallow and rapid. Deep-seated landslides tend to have a delayed response to climatic events, generally being triggered by the accumulation of rainfall over weeks or even years. Shallow, rapid landslides respond quickly to large storms and commonly accompany major floods. Either can be triggered by earthquakes. Significant historic deep-seated lanslides include Aldercrest-Banyan in Kelso that destroyed 135 homes in 1998, costing $50 million in federal disaster aid; Carlyon Beach in northwest Thurston County in 1998, destroying 36 homes; Rolling Bay on Bainbridge Island in 1997, destroying a home and killing its 4 occupants; Piper-Rock Creek in Stevenson in 2007 and continuing to the present, destroying 2 homes and endangering a sewage treatment plant; and the SR 530 slide that killed 43 people. Head scarp, Aldercrest-Banyan landslide, 1998 136 homes were lost in this landslide Coastal Zone Atlas, Carlyon Beach Slope stability map of the Carlyon Beach area, northwest Thurston County (near Olympia), 1980 Carlyon development Mapped as intermediate to unstable terrain Carlyon Beach Landslide In February 1999, after 3 consecutive years of above- average rainfall, movement began on a dormant landslide near Olympia, eventually forcing thirty-six families from their homes. This landslide into Tacoma Narrows occurred 3 days after the 1949 earthquake and generated an 8 ft tsunami at Gig Harbor that reflected back and drowned all of these houses 3 ft deep This landslide at Salmon Beach,triggered by the Nisqually earthquake (2001) damaged the houses that survived in 1949 Shallow rapid landslides occur during and soon after significant rain or rain-on-snow events. The National Flood Insurance Program includes mudflows in its definition of flood, so statistics on damage from shallow rapid landslides are not readily separable from flood damage statistics. The 1997 disaster cost about $300 million, and it appears that well more than half of that was from debris flows. Flood disasters in 1981-82, 1984, 1996, 2006, 2007, and 2009, have significant contributions from debris flows. Including deep-seated landslides, a reasonable average annual loss from landslides over the last 35 years is >>$20 million. Perkins Lane Landslide 1997 This reactivated slide area on Perkins Lane in the Magnolia District of Seattle eventually claimed five houses. This dive shop in west Seattle was destroyed by a landslide that came through its back wall and out the front (January, 1997) This landslide 2 weeks later knocked five rail cars into Puget Sound Rolling Bay, Bainbridge Island, 1997 WA DOE Website Tragedy struck on January 19th, 1997. Within three seconds, 2,000 tons of rock, trees, and soil crushed the Herren home, killing all four family members. On December 3, 2007, following an intense rain, a small slump that picked up water in the stream, bulked up, and transformed into this destructive debris flow... Foundation of brown building and destroyed this restaurant just outside of Olympia, which was rebuilt on the same foundation These houses were damaged by debris flows in January, 2009 And North Fork Stillaguamish on March 22, 2014 What tools are available for planners to mitigate landside hazards? Unfortunately, the availability and quality are uneven. Puget Sound coastal bluff landslide hazard maps for Thurston Co. Landslide hazard mitigation begins with hazard identification. The Division of Geology inventories landslides at https://fortress.wa.gov/dnr/geology/?Theme=natural_hazards Zooming in allows delineation of individual landsides With the identify tool, any individual landslide can be queried for source and for more information The interactive map application (https://fortress.wa.gov/dnr/g eology/) allows you to choose which layers to overlay (for example, compare hazard zones with the underlying geology). Point data can be viewed in relation to surface geology and base map information. The application currently has different map themes, each of which can be accessed through the mapping application itself, or the Washington State Geologic Information Portal main page (http://www.dnr.wa.gov/geol ogyportal). However, this inventory was not systematically collected, is not well documented, is geographically spotty, and is of uneven quality. LIght Detection And Ranging • Airborne scanning laser rangefinder • Differential GPS • Inertial Navigation System 30,000 points per second at ~15 cm accuracy • $400–$1000/mi2, 106 points/mi2, or 0.04–0.1 cents/point Extensive filtering to remove tree canopy (virtual deforestation) Largely as a consequence of the Oso landslide, the Division of Geology received an increase in funding for the 2015-2017 Biennium Received $4.6 million and 7 employees Five in landslide hazards group Two to run a state-wide lidar survey; $1.2 million/year to collect lidar 10-meter DEM from contours 12-ft DEM from LIDAR Landslide mapping • Inventory > Susceptibility > Hazard > Risk Mapping Type Definition 1. Inventory Location and characteristics of existing landslides Location and characteristics of potential landslide; 2. Susceptibility areas with a potential to experience future landslides 3. Hazard Estimated annual probability of a landslide Estimated probability of the occurrence and the 4. Risk probability of the consequence Safeguarding Against Landslide Hazards • Research into property • Get advice from licensed geologist or engineering geologist • Leave a safe setback from steep slopes / bluffs • Keep plants on slopes below house • Reduce surface erosion – avoid discharge onto slope • Reduce ponding and infiltration • Maintain and improve vegetation • Maintain drainage • Don’t irrigate or put drainfields at top of slope / bluff • Don’t dump on slope • Don’t change natural drainage • Don’t cut into the toe of slope • Don’t overlook slide hazards (may slide once every several decades or so) Avoidance is your safest bet! Geologic Hazards • Landslides • Earthquakes • Tsunamis Washington has a high exposure to earthquake and has experienced 15 damaging events since 1872. Geologic evidence demonstrates substantial hazard from faults that have not ruptured since European settlement of the Pacific Northwest. These include the Seattle, Tacoma, Olympia?, southern Whidbey Island, Devil’s Mountain, Canyon River, Boulder Creek, Toppenish Ridge, and Saddle Mountain faults, which are all capable of earthquakes larger than M6.5 at shallow, and therefore highly damaging, depths. Additionally, there is substantial evidence that the Cascadia subduction zone is active and has generated earthquakes >M9.0 (Atwater and others, 2005) The earliest record of earthquakes in south Puget Sound is from 1833 FORT NISQUALLY, PUGET SOUND Saturday, June 29, [1833] "Mr. Heron returned about 9 this morning to breakfast. Afterwards we mounted the north bank of Coe by the path & were occupied nearly all day in collecting specimens of the soil at every hundred yards length from the summit of bank to the ploughed land. H. & I on horseback. While thus engaged our three attendants, McKie, Brown & Peter Tahi, the islander, felt the earth under them shake violently at least twice. Brown first exclaimed, & seemed much alarmed - He & McKie were on their knees at the time & felt violently lifted up, the sensations of Peter I could not ascertain, Mr. H[eron] & I [on horseback] did not perceive anything remarkable - this happened at 20 minutes from 2 by Rendall's watch, which is not far wrong. On returning to the house we learn't that the shock had been felt there, the boards in the floor of house rattling together. The Indians were much struck & said "The Chief's (Heron's) medicine is strong, he has gone up the hill to shake the grounds." In some quarter of the globe, perhaps the Almighty has wrought some dire devastations by earthquake, one of the most powerful & calamitous instruments of chastisement employed against Mankind. The steep & broken faces to Eastward of the islands in the sound render it probable, that they have been severed from the main shore by an earthquake." Washington has earthquake hazards from three different source zones Pioneer Square,1949 Pioneer Square,2001 Deschutes Parkway, 1965 Deschutes Parkway, 2001 Salmon Beach, 2001 Salmon Beach, 1949 BCF DDMF SPF,UPF LRF SWIF SMF FCF SF RMF CRF TF OF SMF TRF SHZ SPF OWL LRF, Little River fault; SMF, Saddle Mountain East and West faults; FCF, Frigid Creek fault; CRF, Canyon River fault; OF, Olympia fault; SHZ, St. Helens Zone; TF, Tacoma fault; SF, Seattle fault; SWIF, Southern Whidbey Island fault; SPF, Strawberry Point fault; UPF, Utsalady Point fault; DDMF, Darrington-Devil’s Mtn. Fault; RMF, Rattlesnake Ridge fault; TRF, Toppenish Ridge fault; SPF, Satus Pass fault; SMF, Saddle Mountain fault; OWL, Olympic-Wallowa Lineament. From Sherrod and others, 2008 SMF CRF from Clement and others, BSSA, 2010 In order to assess faults, we need to use new technologies to locate faults and dig trenches to expose them for study from Clement and others, BSSA, 2010 Another suspected fault runs through the Olympia area. We call it the Olympia structure but some people call it the Olympia fault. It was initially identified on the basis of geophysical information. There is also paleoseismic data in support of an Olympia fault. Jack Odum and Bill Stephenson have recently done seismic reflection profiling along Steamboat Island Road and have preliminarily made some interpretationsof the Olympia structure (or maybe it is a fault). Skokomish Delta terrain and magnetic contacts. This map shows SRTM topography. D The scarp shows up clearly, even in these Shuttle data. Notice the topographic lineament northwest of and on strike with the scarp (yellow arrow). This lineament is intriguing but has a sense of offset (southwest side up) opposite from the sense of the scarp.
Recommended publications
  • Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information

    Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information

    Cambridge University Press 978-1-108-44568-9 — Active Faults of the World Robert Yeats Index More Information Index Abancay Deflection, 201, 204–206, 223 Allmendinger, R. W., 206 Abant, Turkey, earthquake of 1957 Ms 7.0, 286 allochthonous terranes, 26 Abdrakhmatov, K. Y., 381, 383 Alpine fault, New Zealand, 482, 486, 489–490, 493 Abercrombie, R. E., 461, 464 Alps, 245, 249 Abers, G. A., 475–477 Alquist-Priolo Act, California, 75 Abidin, H. Z., 464 Altay Range, 384–387 Abiz, Iran, fault, 318 Alteriis, G., 251 Acambay graben, Mexico, 182 Altiplano Plateau, 190, 191, 200, 204, 205, 222 Acambay, Mexico, earthquake of 1912 Ms 6.7, 181 Altunel, E., 305, 322 Accra, Ghana, earthquake of 1939 M 6.4, 235 Altyn Tagh fault, 336, 355, 358, 360, 362, 364–366, accreted terrane, 3 378 Acocella, V., 234 Alvarado, P., 210, 214 active fault front, 408 Álvarez-Marrón, J. M., 219 Adamek, S., 170 Amaziahu, Dead Sea, fault, 297 Adams, J., 52, 66, 71–73, 87, 494 Ambraseys, N. N., 226, 229–231, 234, 259, 264, 275, Adria, 249, 250 277, 286, 288–290, 292, 296, 300, 301, 311, 321, Afar Triangle and triple junction, 226, 227, 231–233, 328, 334, 339, 341, 352, 353 237 Ammon, C. J., 464 Afghan (Helmand) block, 318 Amuri, New Zealand, earthquake of 1888 Mw 7–7.3, 486 Agadir, Morocco, earthquake of 1960 Ms 5.9, 243 Amurian Plate, 389, 399 Age of Enlightenment, 239 Anatolia Plate, 263, 268, 292, 293 Agua Blanca fault, Baja California, 107 Ancash, Peru, earthquake of 1946 M 6.3 to 6.9, 201 Aguilera, J., vii, 79, 138, 189 Ancón fault, Venezuela, 166 Airy, G.
  • What's Shaking

    What's Shaking

    ISSUE 03 - February 2016 WHAT’S SHAKING newsletter of the THE NEVADA SEISMOLOGICAL LABORATORY Earthquake Update NEVADA Carson RENO City Maps of earthquakes located by the Nevada Seismo- logical Laboratory (NSL) between 1/1/16 and 1/31/16, within the NSL network (right). Truckee Meadows region (above), Hawthorne, Nevada area (bottom left) and the area surrounding Las Vegas, Nevada (bottom right). HAWTHORNE Earthquakes located by the NSL (1/1/16-1/31/16) ML Quantity 4.0+ 1 3.0-3.9 2 2.0-2.9 67 Nevada 1.0-1.9 478 National ML < 1.0 809 Security Site Total 1357 eismicity during January included a small sequence near Haw- Sthorne, Nevada (above), and a notable sequence near Enter- LAS VEGAS prise, Utah (right). The largest of these Hawthorne events measured M3.2, and several events greater than M2.0 were also recorded. An event (M4.3) that occurred near Enterprise, Utah shook several eastern Nevada communities on January 15, 2016. The Sheldon Sequence also continues to be active in northwestern Nevada. Maps compiled by D. Molisee (2016) www.graphicdiffer.comwww.seismo.unr.edu @NVSeismoLab1 DEVELOPMENTS NSL Graduate Students Leverage Funding from the National Science Foundation unding for Steve Angster and will focus on the Agai-Pai, Indian FIan Pierce has come from Head, Gumdrop, Benton Springs, a National Science Foundation and Petrified fault systems, while grant (Steve Wesnousky, lead PI) Ian will study the Tahoe, Carson, focused on the deformation pat- Antelope Valley, Smith Valley, Ma- tern and kinematics of the Walker son Valley, and Walker Lake fault Lane.
  • South Tacoma Way, Circa 1913, Photo Courtesy of the Tacoma Public Library, Amzie D

    South Tacoma Way, Circa 1913, Photo Courtesy of the Tacoma Public Library, Amzie D

    The west side of the 5200 block of South Tacoma Way, circa 1913, photo courtesy of the Tacoma Public Library, Amzie D. Browning Collection 158 2 011 Historic South Tacoma Way South Tacoma Way Business District In early 2011, Historic Tacoma reached out to the 60+ member South Tacoma Business District Association as part of its new neighborhood initiative. The area is home to one of the city’s most intact historic commercial business districts. A new commuter rail station is due to open in 2012, business owners are interested in S 52nd St taking advantage of City loan and grant programs for façade improvements, and Historic Tacoma sees S Washington St great opportunities in partnering with the district. S Puget Sound Ave The goals of the South Tacoma project are to identify and assess historic structures and then to partner with business owners and the City of Tacoma to conserve and revitalize the historic core of the South Tacoma Business District. The 2011 work plan includes: • conducting a detailed inventory of approximately 50 commercial structures in the historic center of the district • identification of significant and endangered South Way Tacoma properties in the district • development of action plans for endangered properties • production of a “historic preservation resource guide for community leaders” which can be S 54th St used by community groups across the City • ½ day design workshop for commercial property owners • production & distribution of a South Tacoma Business District tour guide and map • nominations to the Tacoma Register of Historic Places as requested by property owners • summer walking tour of the district Acknowledgements Project funding provided by Historic Tacoma, the South Tacoma Business District Association, the South Tacoma Neighborhood Council, the University of Washington-Tacoma, and Jim and Karen Rich.
  • South Puget Sound Community College Year Three Mid-Cycle Evaluation

    South Puget Sound Community College Year Three Mid-Cycle Evaluation

    South Puget Sound Community College Year Three Mid-Cycle Evaluation Dr. Timothy Stokes President September, 2014 Table of Contents Report on Year One Recommendation ......................................................................................................... 1 Mission .......................................................................................................................................................... 1 Part I .............................................................................................................................................................. 1 Mission Fulfillment .................................................................................................................................... 1 Operational Planning ................................................................................................................................ 2 Core Themes, Objectives and Indicators .................................................................................................. 3 Part II ............................................................................................................................................................. 4 Rationale for Indicators of Achievement .................................................................................................. 5 Increase Student Retention (Objective 1.A) ......................................................................................... 5 Support Student Completion (Objective 1.B) ......................................................................................
  • A Review of Geological Records of Large Tsunamis at Vancouver Island, British Columbia, and Implications for Hazard John J

    A Review of Geological Records of Large Tsunamis at Vancouver Island, British Columbia, and Implications for Hazard John J

    Quaternary Science Reviews 19 (2000) 849}863 A review of geological records of large tsunamis at Vancouver Island, British Columbia, and implications for hazard John J. Clague! " *, Peter T. Bobrowsky#, Ian Hutchinson$ !Depatment of Earth Sciences and Institute for Quaternary Research, Simon Fraser University, Burnaby, BC, Canada V5A 1S6 "Geological Survey of Canada, 101 - 605 Robson St., Vancouver, BC, Canada V6B 5J3 #Geological Survey Branch, P.O. Box 9320, Stn Prov Govt, Victoria, BC, Canada V8W 9N3 $Department of Geography and Institute for Quaternary Research, Simon Fraser University, Burnaby, Canada BC V5A 1S6 Abstract Large tsunamis strike the British Columbia coast an average of once every several hundred years. Some of the tsunamis, including one from Alaska in 1964, are the result of distant great earthquakes. Most, however, are triggered by earthquakes at the Cascadia subduction zone, which extends along the Paci"c coast from Vancouver Island to northern California. Evidence of these tsunamis has been found in tidal marshes and low-elevation coastal lakes on western Vancouver Island. The tsunamis deposited sheets of sand and gravel now preserved in sequences of peat and mud. These sheets commonly contain marine fossils, and they thin and "ne landward, consistent with deposition by landward surges of water. They occur in low-energy settings where other possible depositional processes, such as stream #ooding and storm surges, can be ruled out. The most recent large tsunami generated by an earthquake at the Cascadia subduction zone has been dated in Washington and Japan to AD 1700. The spatial distribution of the deposits of the 1700 tsunami, together with theoretical numerical modelling, indicate wave run-ups of up to 5 m asl along the outer coast of Vancouver Island and up to 15}20 m asl at the heads of some inlets.
  • Geologic History of Siletzia, a Large Igneous Province in the Oregon And

    Geologic History of Siletzia, a Large Igneous Province in the Oregon And

    Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Wells, R., Bukry, D., Friedman, R., Pyle, D., Duncan, R., Haeussler, P., & Wooden, J. (2014). Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot. Geosphere, 10 (4), 692-719. doi:10.1130/GES01018.1 10.1130/GES01018.1 Geological Society of America Version of Record http://cdss.library.oregonstate.edu/sa-termsofuse Downloaded from geosphere.gsapubs.org on September 10, 2014 Geologic history of Siletzia, a large igneous province in the Oregon and Washington Coast Range: Correlation to the geomagnetic polarity time scale and implications for a long-lived Yellowstone hotspot Ray Wells1, David Bukry1, Richard Friedman2, Doug Pyle3, Robert Duncan4, Peter Haeussler5, and Joe Wooden6 1U.S. Geological Survey, 345 Middlefi eld Road, Menlo Park, California 94025-3561, USA 2Pacifi c Centre for Isotopic and Geochemical Research, Department of Earth, Ocean and Atmospheric Sciences, 6339 Stores Road, University of British Columbia, Vancouver, BC V6T 1Z4, Canada 3Department of Geology and Geophysics, University of Hawaii at Manoa, 1680 East West Road, Honolulu, Hawaii 96822, USA 4College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, Oregon 97331-5503, USA 5U.S. Geological Survey, 4210 University Drive, Anchorage, Alaska 99508-4626, USA 6School of Earth Sciences, Stanford University, 397 Panama Mall Mitchell Building 101, Stanford, California 94305-2210, USA ABSTRACT frames, the Yellowstone hotspot (YHS) is on southern Vancouver Island (Canada) to Rose- or near an inferred northeast-striking Kula- burg, Oregon (Fig.
  • Development of a Hydrodynamic Model of Puget Sound and Northwest Straits

    Development of a Hydrodynamic Model of Puget Sound and Northwest Straits

    PNNL-17161 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Development of a Hydrodynamic Model of Puget Sound and Northwest Straits Z Yang TP Khangaonkar December 2007 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. PACIFIC NORTHWEST NATIONAL LABORATORY operated by BATTELLE for the UNITED STATES DEPARTMENT OF ENERGY under Contract DE-AC05-76RL01830 Printed in the United States of America Available to DOE and DOE contractors from the Office of Scientific and Technical Information, P.O. Box 62, Oak Ridge, TN 37831-0062; ph: (865) 576-8401 fax: (865) 576-5728 email: [email protected] Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm This document was printed on recycled paper.
  • Earthquake Hazard

    Earthquake Hazard

    SUB-SECTION 4G.2 PUYALLUP TRIBE ALL HAZARD MITIGATION PLAN EARTHQUAKE HAZARD Table of Contents TABLE OF CONTENTS ............................................................................................... 1 IDENTIFICATION DESCRIPTION ................................................................................ 2 DEFINITION ............................................................................................................. 2 TYPES .................................................................................................................... 2 SECONDARY HAZARDS: ................................................................................................ 3 PROFILE ................................................................................................................... 5 LOCATION AND EXTENT ............................................................................................... 5 VULNERABILITY ....................................................................................................... 15 IMPACTS ............................................................................................................... 16 RESOURCE DIRECTORY .......................................................................................... 24 REGIONAL ............................................................................................................. 24 NATIONAL ............................................................................................................. 24 ENDNOTES ............................................................................................................
  • The Really Big One an Earthquake Will Destroy a Sizable Portion of the Coastal Northwest

    The Really Big One an Earthquake Will Destroy a Sizable Portion of the Coastal Northwest

    The Earthquake That Will Devastate the Pacific Northwest - The New Yorker Page 1 of 23 Annals of Seismology JULY 20, 2015 ISSUE The Really Big One An earthquake will destroy a sizable portion of the coastal Northwest. The question is when. BY KATHRYN SCHULZ TABLE OF CONTENTS TWEET hen the 2011 earthquake and tsunami struck WTohoku, Japan, Chris Goldfinger was two hundred miles away, in the city of Kashiwa, at an international meeting on seismology. As the shaking started, everyone in the room began to laugh. Earthquakes are common in Japan—that one was the third of the week—and the participants were, after all, at a seismology conference. Then everyone in the room checked the time. The next full-margin rupture of the Cascadia subduction zone will spell the worst natural Seismologists know that how long disaster in the history of the continent. ILLUSTRATION BY CHRISTOPH NIEMANN; MAP BY an earthquake lasts is a decent ZIGGYMAJ / GETTY proxy for its magnitude. The 1989 earthquake in Loma Prieta, http://www.newyorker.com/magazine/2015/07/20/the-really-big-one 8/10/2015 The Earthquake That Will Devastate the Pacific Northwest - The New Yorker Page 2 of 23 California, which killed sixty-three people and caused six billion dollars’ worth of damage, lasted about fifteen seconds and had a magnitude of 6.9. A thirty-second earthquake generally has a magnitude in the mid- sevens. A minute-long quake is in the high sevens, a two-minute quake has entered the eights, and a three-minute quake is in the high eights.
  • Fully-Coupled Simulations of Megathrust Earthquakes and Tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone

    Fully-Coupled Simulations of Megathrust Earthquakes and Tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone

    Noname manuscript No. (will be inserted by the editor) Fully-coupled simulations of megathrust earthquakes and tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone Gabriel C. Lotto · Tamara N. Jeppson · Eric M. Dunham Abstract Subduction zone earthquakes can pro- strate that horizontal seafloor displacement is a duce significant seafloor deformation and devas- major contributor to tsunami generation in all sub- tating tsunamis. Real subduction zones display re- duction zones studied. We document how the non- markable diversity in fault geometry and struc- hydrostatic response of the ocean at short wave- ture, and accordingly exhibit a variety of styles lengths smooths the initial tsunami source relative of earthquake rupture and tsunamigenic behavior. to commonly used approach for setting tsunami We perform fully-coupled earthquake and tsunami initial conditions. Finally, we determine self-consistent simulations for three subduction zones: the Japan tsunami initial conditions by isolating tsunami waves Trench, the Nankai Trough, and the Cascadia Sub- from seismic and acoustic waves at a final sim- duction Zone. We use data from seismic surveys, ulation time and backpropagating them to their drilling expeditions, and laboratory experiments initial state using an adjoint method. We find no to construct detailed 2D models of the subduc- evidence to support claims that horizontal momen- tion zones with realistic geometry, structure, fric- tum transfer from the solid Earth to the ocean is tion, and prestress. Greater prestress and rate-and- important in tsunami generation. state friction parameters that are more velocity- weakening generally lead to enhanced slip, seafloor Keywords tsunami; megathrust earthquake; deformation, and tsunami amplitude.
  • Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching

    Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching

    Portland State University PDXScholar Dissertations and Theses Dissertations and Theses Summer 9-8-2017 Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching Kristofer Tyler Hornsby Portland State University Follow this and additional works at: https://pdxscholar.library.pdx.edu/open_access_etds Part of the Geology Commons, and the Geomorphology Commons Let us know how access to this document benefits ou.y Recommended Citation Hornsby, Kristofer Tyler, "Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching" (2017). Dissertations and Theses. Paper 3890. https://doi.org/10.15760/etd.5778 This Thesis is brought to you for free and open access. It has been accepted for inclusion in Dissertations and Theses by an authorized administrator of PDXScholar. Please contact us if we can make this document more accessible: [email protected]. Constraining the Holocene Extent of the Northwest Meers Fault, Oklahoma Using High-Resolution Topography and Paleoseismic Trenching by Kristofer Tyler Hornsby A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science In Geology Thesis Committee: Ashley R. Streig, Chair Scott E.K. Bennett Adam M. Booth Portland State University 2017 ABSTRACT The Meers Fault (Oklahoma) is one of few seismogenic structures with Holocene surface expression in the stable continental region of North America. Only the ~37 km- long southeastern section of the ~55 km long Meers Fault is interpreted to be Holocene- active. The ~17 km-long northwestern section is considered to be Quaternary-active (pre- Holocene); however, its low-relief geomorphic expression and anthropogenic alteration have presented difficulties in evaluating the fault length and style of Holocene deformation.
  • Mondo Quake in Pacific Northwest? by Leander Kahney

    Mondo Quake in Pacific Northwest? by Leander Kahney

    Mondo Quake in Pacific Northwest? By Leander Kahney Story location: http://www.wired.com/news/technology/0,1282,61322,00.html 02:00 AM Nov. 24, 2003 PT Geologists have discovered evidence of a massively powerful earthquake zone beneath the Pacific Northwest just offshore from the Seattle area. They made the discovery by piecing together ancient accounts of a giant Japanese tsunami and a computer simulation of a huge temblor in the 17th century. Thought to be inactive, the earthquake zone runs 600 miles up the Pacific Coast from Northern California to southern British Columbia. It appears to be subject to monster quakes every 500 years. Known as the Cascadia subduction zone, the fault could threaten Vancouver, Portland and Seattle, which are full of buildings and high rises not built to withstand massive earthquakes. "This region has the potential for truly enormous earthquakes," said Brian Atwater of the U.S. Geological Survey, one of three authors of a new paper about a giant 17th-century quake along the fault. Published in the Journal of Geophysical Research-Solid Earth, the paper catalogs evidence for a magnitude-9 quake, which sent a tsunami across the Pacific to wreak havoc in Shogun-era Japan. The idea that the Cascadia region caused the tsunami isn't new; Japanese researchers first floated the idea in 1996. But the paper's authors present a solid case that a magnitude-9 quake on Tuesday, January 26, 1700, sent a 15-foot tsunami into Japan about 14 hours later. The paper, authored by Atwater, Kenji Satake of the Geological Survey of Japan and Kelin Wang of the Geological Survey of Canada, also presents a new computer model of the cataclysmic event.