DOCSLIB.ORG

Geologic Evidence of Earthquakes at the Snohomish Delta, Washington, in the Past 1200 Yr

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geologic Evidence of Earthquakes at the Snohomish Delta, Washington, in the Past 1200 Yr Geologic evidence of earthquakes at the Snohomish delta, Washington, in the past 1200 yr Joanne Bourgeois* Department of Geological Sciences, University of Washington, Seattle, Washington 98195, USA Samuel Y. Johnson² U.S. Geological Survey, M.S. 966, Box 25046, Denver Federal Center, Denver, Colorado 80225, USA ABSTRACT suggest that one set of these dikes formed 1996, 1999a; Pratt et al., 1997). Only the ca. A.D. 910±990; radiocarbon ages on a downgoing plate has produced large historic Exposed channel banks along distribu- younger set indicate a limiting maximum earthquakes (e.g., 1949 and 1965; Langston taries of the lower Snohomish delta in the age of A.D. 1400±1640. We also interpret a and Blum, 1977; Baker and Langston, 1987; Puget Lowland of Washington reveal evi- sharp lithologic change, from olive-gray, Chleborad and Schuster, 1998). dence of at least three episodes of liquefac- rhizome-rich mud to grayer, rhizome-poor Paleoseismologic studies in southwest tion, at least one event of abrupt subsi- mud, ;1 m above the couplet, to indicate a Washington suggest that seven great earth- dence, and at least one tsunami since ca. second abrupt lowering of the marsh sur- quakes (M . 8) have occurred at the Cascadia A.D. 800. The 45 measured stratigraphic face during an earthquake ca. A.D. 1040± plate boundary since ca. 3500 yr B.P. (Atwater sections consist mostly of 2±4 m of olive- 1400, but no conclusive liquefaction struc- and Hemphill-Haley, 1997), including the gray, intertidal mud containing abundant tures have been identi®ed at this horizon. most recent (M ; 9) event in A.D. 1700 (e.g., marsh plant rhizomes. The most distinctive Two distinctive coarse-sand laminae, 30±80 Nelson et al., 1995; Satake et al., 1996). In stratigraphic unit is a couplet comprising a cm below the couplet, may record tsunamis the Puget Lowland, Bucknam et al. (1992) 0.523-cm-thick, laminated, ®ning-upward, older than A.D. 800. showed that a large (M . 7) earthquake oc- tsunami-laid sand bed overlain by 2210 cm Thus, study shows that in the past ;1200 curred on the Seattle fault ca. A.D. 900±930 of gray clay. We correlated the couplet, yr, this part of Washington's Puget Low- (Atwater, 1999). Recognition of these events which is generally ;2 m below the modern land has been subjected to stronger ground has boosted estimates of regional seismic haz- marsh surface, across an ;20 km2 area. shaking than in historic times, since ca. ard (Frankel et al., 1996) and demonstrates the Sand dikes and sand-®lled cracks to 1 m 1870. need for a more complete catalog of the num- wide, which terminate upward at the cou- ber, frequency, sources, magnitudes, and ef- plet, and sand volcanoes preserved at the Keywords: earthquakes, paleoseismicity, Pu- fects of large earthquakes affecting the Puget level of the sand bed record liquefaction at get Lowland, sedimentology, stratigraphy. Lowland. the same time as couplet deposition. Differ- Here we report geologic evidence for paleo- earthquakes from the Snohomish River delta ences in the type and abundance of marsh INTRODUCTION plant rhizomes across the couplet horizon, near Everett in the northern Puget Lowland as well as the gray clay layer, suggest that (Figs. 1 and 3), where there is minimal his- The densely populated Puget Lowland of compaction during this liquefaction led to torical information on earthquake effects. Del- Washington State (Figs. 1 and 2) occupies a abrupt, local lowering of the marsh surface tas are particularly good sites for paleoseis- dynamic geologic setting in the forearc of the by as much as 50±75 cm. Radiocarbon ages mologic investigations because their young, North American plate above the Cascadia sub- show that the tsunami and liquefaction date loosely packed sediments are prone to coseis- duction zone. Complex plate interactions from ca. A.D. 800 to 980, similar to the age mic liquefaction, compaction, and subsidence, along this convergent continental margin are of a large earthquake on the Seattle fault, and because their low elevation and proximity the driving force for a signi®cant, yet poorly 50 km to the south. to a water body make them susceptible to tsu- understood earthquake hazard (Ludwin et al., We have found evidence for at least two, namis. Bank exposures along tidal distributar- 1991; Rogers et al., 1996). Sources for mod- and possibly as many as ®ve, other earth- ies of the lower Snohomish delta show evi- erate or larger earthquakes include slip on the quakes in the measured sections. At two or dence of at least three liquefaction events, Cascadia plate boundary (interplate), ruptures more stratigraphic levels above the couplet, inundation by at least one tsunami, and at least in the downgoing Juan de Fuca plate 60 km sand dikes locally feed sand volcanoes. Ra- ; one episode of abrupt subsidence, all since ca. below Puget Sound (intraplate), and move- diocarbon ages and stratigraphic position A.D. 800. We infer that the most distinctive ment on shallow crustal faults in the North stratigraphic horizon (ca. A.D. 800±1100) re- *E-mail: [email protected]. American plate such as the Seattle fault or cords strong ground motion and tsunami in- ²Corresponding author; e-mail: sjohnson@usgs. southern Whidbey Island fault (Figs. 1 and 2) undation associated with the A.D. 900±930 gov. (Gower et al., 1985; Johnson et al., 1994, Seattle fault earthquake. GSA Bulletin; April 2001; v. 113; no. 4; p. 482±494; 9 ®gures; 3 tables; Data Repository item 2001034. For permission to copy, contact Copyright Clearance Center at www.copyright.com 482 q 2001 Geological Society of America PALEOSEISMOLOGY ON THE SNOHOMISH DELTA SNOHOMISH RIVER DELTA The Snohomish River begins at the con¯u- ence of the Skykomish and Snoqualmie Rivers and empties into Possession Sound (Fig. 1). At its lower end, the Snohomish ¯ows through a wide (;4 km) postglacial valley bounded by morainal deposits of the last (Fraser) glacia- tion. About 12 km upstream from Possession Sound, at an elevation of ,1.5 m above sea level, the main channel divides into several distributaries, or sloughs (Fig. 3). Spring-tide range in the sloughs is as much as 4.5 m. Snohomish delta lowlands are now primar- ily undeveloped wetlands or are used for ag- riculture. Lumber mills and storage, marinas, sewage treatment plants, and a hazardous waste site are also located on the delta plain. The delta is crossed by an interstate highway (I-5), the Burlington-Northern railroad, and a busy local highway. Agriculture on the delta is dependent on a system of dikes and levees, construction of which began in 1876 (Dunnell and Fuller, 1975). The cities of Everett and Marysville, ¯anking the Snohomish delta, were settled in the late 1870s and early 1880s. The northwestern part of the delta is on the Tulalip Indian Reservation. Cutbanks along both the main river channel Figure 1. Generalized geologic map of the Puget Lowland region showing location of and the sloughs in the lower delta typically ex- Snohomish River delta (SRD, area shown in Fig. 3) and selected regional crustal faults or pose, at maximum low tide, 1±4 m of strata de- geophysical lineaments (heavy dashed lines). Abbreviations: CÐCultus Bay; DMFÐDevils posited in about the past 1500 yr (Figs. 4 and Mountain fault; EÐEverett; LWÐLake Washington; OÐOlympia; PÐPossession Sound; 5). These strata, in general, record the building PSÐPuget Sound; SÐSeattle; SFÐSeattle fault; SJÐSan Juan Islands; SRÐSnohomish up of the delta, from channel point-bar deposits River; SKRÐSkykomish River; SNRÐSnoqualmie River; SWFÐsouthern Whidbey Is- to intertidal mud ¯ats to supratidal marsh de- land fault; TÐTacoma; WÐWest Point; WIÐWhidbey Island. Faults based on Gower posits. Marsh deposits predominate in studied (1985) and Johnson et al. (1996, 1999a). outcrops, and in-growth-position plant material and detrital wood debris are abundant in these sediments. Although tidal laminae are visible on weathered surfaces, they have been largely dis- rupted by bioturbation associated with modern and relict marsh vegetation. Snohomish River delta channels and marsh- es appear not to have migrated much since ca. A.D. 800. Since a United States Coast Survey hydrographic map was made in 1884, there has been neither signi®cant lateral migration of channels nor progradation of the mouth. Sedimentary facies, including fossil plant ma- terial, in cutbanks are at approximately the same elevations as facies currently being de- posited at nearby locations. Thus sediment supply appears to be in approximate balance with the combined effects of subsidence and slow sea-level rise. Vertical aggradation rates Figure 2. Schematic view of the Paci®c Northwest continental margin (no scale) showing are ;2 m/1 k.y., based on our radiocarbon distribution of three types of earthquakes that affect the region. dating (Table 1; Fig. 4). Geological Society of America Bulletin, April 2001 483 BOURGEOIS and JOHNSON SNOHOMISH SEDIMENTARY ENVIRONMENTS AND FACIES The lower, modern Snohomish delta com- prises ®ve basic subenvironments, in succes- sion from deeper to shallower: (1) subtidal channels, (2) lower intertidal ¯ats and point bars, (3) upper intertidal ¯ats and point bars, (4) supratidal marsh, and (5) lower delta plain and levees. This same succession is present in late Holocene facies in outcrop, produced as distributary channels migrate laterally and as the delta aggrades. Facies are distinguished primarily by sediment texture and color, growth-position plant fossils (see Table 2), and sedimentary structures. Our observations of the modern delta environments and the out- crop facies, including modern and fossil veg- etation, are summarized in the GSA Data Re- pository (Figs. DR1±DR31). Subtidal The major subtidal channel environments of the modern delta (i.e., the axes of the main channel and its distributaries) are constantly submerged, so we did not directly observe and describe them.
Load more

Recommended publications
  • Paleoseismology of the North Anatolian Fault at Güzelköy
    Paleoseismology of the North Anatolian Fault at Güzelköy (Ganos segment, Turkey): Size and recurrence time of earthquake ruptures west of the Sea of Marmara Mustapha Meghraoui, M. Ersen Aksoy, H Serdar Akyüz, Matthieu Ferry, Aynur Dikbaş, Erhan Altunel To cite this version: Mustapha Meghraoui, M. Ersen Aksoy, H Serdar Akyüz, Matthieu Ferry, Aynur Dikbaş, et al.. Pale- oseismology of the North Anatolian Fault at Güzelköy (Ganos segment, Turkey): Size and recurrence time of earthquake ruptures west of the Sea of Marmara. Geochemistry, Geophysics, Geosystems, AGU and the Geochemical Society, 2012, 10.1029/2011GC003960. hal-01264190 HAL Id: hal-01264190 https://hal.archives-ouvertes.fr/hal-01264190 Submitted on 1 Feb 2016 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Article Volume 13, Number 4 12 April 2012 Q04005, doi:10.1029/2011GC003960 ISSN: 1525-2027 Paleoseismology of the North Anatolian Fault at Güzelköy (Ganos segment, Turkey): Size and recurrence time of earthquake ruptures west of the Sea of Marmara Mustapha Meghraoui Institut de Physique du Globe de Strasbourg (UMR 7516), F-67084 Strasbourg, France ([email protected]) M. Ersen Aksoy Institut de Physique du Globe de Strasbourg (UMR 7516), F-67084 Strasbourg, France Eurasia Institute of Earth Sciences, Istanbul Technical University, 34469 Istanbul, Turkey Now at Instituto Dom Luiz, Universidade de Lisboa, P-1750-129 Lisbon, Portugal H.
    [Show full text]
  • Study of Recent Tsunamis Sheds Light on Earthquakes
    Eos, Vol. 75, No. 1, January 4, 1994 resentative Peter Webb, will be held at the than 10 m, and a total of about 1500 people an important calibration to quantify such Byrd Polar Research Center at The Ohio were killed. Field surveys were made for geological studies. State University, March 6-7, 1994, to gauge these tsunamis and reported in Eos [Satake Coastal behavior of tsunamis needs to be the U.S. community's breadth of interest and et al., 1993; Yeh et al., 1993; Hokkaido Tsu­ examined in more detail. For example, the to discuss the submission of proposals for nami Survey Team, 1993]. The survey teams, field survey of the Hokkaido tsunami re­ the June 1, 1994, U.S. Antarctic Program typically consisting of scientists and engi­ vealed that the maximum run-up height was deadline. Persons interested in attending this neers from various fields, documented the 30 m in a small valley on Okushiri Island, workshop or in receiving further information behavior of the tsunamis in detail. Tsunami but 20 m or less a short distance away; the on the Cape Roberts Project should contact survey data are used for various types of re­ run-up height varies significantly with local Peter Webb. search, ranging from coastal behavior of tsu­ topography. Three-dimensional run-up pro- A project prospectus, Antarctic Strati- namis to past and future earthquakes. cecsses are currently being modeled by the­ graphic Drilling, Cape Roberts Project, Work­ Most tsunamis are caused by shallow oretical, numerical, and experimental meth­ shop Report, can be obtained from the rep­ submarine earthquakes.
    [Show full text]
  • Long-Term Perspectives on Giant Earthquakes and Tsunamis at Subduction Zones∗
    ANRV309-EA35-12 ARI 20 March 2007 15:19 Long-Term Perspectives on Giant Earthquakes and Tsunamis at Subduction Zones∗ Kenji Satake1 and Brian F. Atwater2 1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8567, Japan; email: [email protected] 2U.S. Geological Survey at University of Washington, Seattle, Washington 98195-1310; email: [email protected] Annu. Rev. Earth Planet. Sci. 2007. 35:349–74 Key Words First published online as a Review in Advance on paleoseismology, earthquake recurrence, earthquake forecasting, January 17, 2007 Sumatra, Chile, Cascadia, Hokkaido The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract by Brian Atwater on 05/14/07. For personal use only. This article’s doi: Histories of earthquakes and tsunamis, inferred from geological ev- 10.1146/annurev.earth.35.031306.140302 idence, aid in anticipating future catastrophes. This natural warn- Copyright c 2007 by Annual Reviews. ! ing system now influences building codes and tsunami planning in All rights reserved the United States, Canada, and Japan, particularly where geology 0084-6597/07/0530-0349$20.00 demonstrates the past occurrence of earthquakes and tsunamis larger Annu. Rev. Earth Planet. Sci. 2007.35:349-374. Downloaded from arjournals.annualreviews.org ∗The U.S. Government has the right to retain a than those known from written and instrumental records. Under fa- nonexclusive, royalty-free license in and to any vorable circumstances, paleoseismology can thus provide long-term copyright covering this paper. advisories of unusually large tsunamis. The extraordinary Indian Ocean tsunami of 2004 resulted from a fault rupture more than 1000 km in length that included and dwarfed fault patches that had broken historically during lesser shocks.
    [Show full text]
  • Preface: Marine and Lake Paleoseismology
    Open Access Nat. Hazards Earth Syst. Sci., 13, 3469–3478, 2013 Natural Hazards www.nat-hazards-earth-syst-sci.net/13/3469/2013/ doi:10.5194/nhess-13-3469-2013 and Earth System © Author(s) 2013. CC Attribution 3.0 License. Sciences Preface: Marine and Lake Paleoseismology E. Gràcia1, G. Lamarche2, H. Nelson3, and D. Pantosti4 1ICM-CSIC, Barcelona, Spain 2NIWA, Wellington, New Zealand 3IACT-CSIC, Granada, Spain 4INGV, Rome, Italy Correspondence to: E. Gràcia ([email protected]) Abstract. This special issue of Natural Hazards and Earth to provide the physical parameters that quantify earthquake System Sciences (NHESS) contains 16 papers that resulted sources seismic potential, such as fault geometry, slip rate, from the European Science Foundation (ESF) Research Con- recurrence period, displacement per event, and elapsed time ference “Submarine Paleoseismology: The Offshore Search since the last event (Pantosti and Yeats, 1993). These param- of Large Holocene Earthquakes” that was held at the Univer- eters are commonly used for seismic hazard evaluation in sitätszentrum Obergurgl (Austria), from 11 to 16 September Cascadia, California and New Zealand (Barnes and Pondard, 2010 (Pantosti et al., 2011). The conference enabled scien- 2010; Goldfinger et al., 2003a; Stirling et al., 2012), where tists from a number of existing lines of research to give an deformation rates are high, and where the paleoseismologi- official start and international recognition to subaqueous pa- cal studies are at the avant-garde. In these regions, paleoseis- leoseismology. mic studies have enabled great improvement of the hazard The scope of this Special Issue is built on the content of assessment (e.g.
    [Show full text]
  • Repeated Occurrence of Surface-Sediment Remobilization
    Ikehara et al. Earth, Planets and Space (2020) 72:114 https://doi.org/10.1186/s40623-020-01241-y FULL PAPER Open Access Repeated occurrence of surface-sediment remobilization along the landward slope of the Japan Trench by great earthquakes Ken Ikehara1* , Kazuko Usami1,2 and Toshiya Kanamatsu3 Abstract Deep-sea turbidites have been utilized to understand the history of past large earthquakes. Surface-sediment remo- bilization is considered to be a mechanism for the initiation of earthquake-induced turbidity currents, based on the studies on the event deposits formed by recent great earthquakes, such as the 2011 Tohoku-oki earthquake, although submarine slope failure has been considered to be a major contributor. However, it is still unclear that the surface-sed- iment remobilization has actually occurred in past great earthquakes. We examined a sediment core recovered from the mid-slope terrace (MST) along the Japan Trench to fnd evidence of past earthquake-induced surface-sediment remobilization. Coupled radiocarbon dates for turbidite and hemipelagic muds in the core show small age diferences (less than a few 100 years) and suggest that initiation of turbidity currents caused by the earthquake-induced surface- sediment remobilization has occurred repeatedly during the last 2300 years. On the other hand, two turbidites among the examined 11 turbidites show relatively large age diferences (~ 5000 years) that indicate the occurrence of large sea-foor disturbances such as submarine slope failures. The sedimentological (i.e., of diatomaceous nature and high sedimentation rates) and tectonic (i.e., continuous subsidence and isolated small basins) settings of the MST sedimentary basins provide favorable conditions for the repeated initiation of turbidity currents and for deposition and preservation of fne-grained turbidites.
    [Show full text]
  • Diverse Rupture Modes for Surface-Deforming Upper Plate Earthquakes in the Southern Puget Lowland of Washington State
    Diverse rupture modes for surface-deforming upper plate earthquakes in the southern Puget Lowland of Washington State Alan R. Nelson1,*, Stephen F. Personius1, Brian L. Sherrod2, Harvey M. Kelsey3, Samuel Y. Johnson4, Lee-Ann Bradley1, and Ray E. Wells5 1Geologic Hazards Science Center, U.S. Geological Survey, MS 966, PO Box 25046, Denver, Colorado 80225, USA 2U.S. Geological Survey at Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, Washington 98195, USA 3Department of Geology, Humboldt State University, Arcata, California 95521, USA 4Western Coastal and Marine Geology Science Center, U.S. Geological Survey, 400 Natural Bridges Drive, Santa Cruz, California 95060, USA 5Geology, Minerals, Energy, and Geophysics Science Center, U.S. Geological Survey, 345 Middlefi eld Road, MS 973, Menlo Park, California 94025, USA ABSTRACT earthquakes. In the northeast-striking Saddle migrating forearc has deformed the Seto Inland Mountain deformation zone, along the west- Sea into a series of basins and uplifts bounded Earthquake prehistory of the southern ern limit of the Seattle and Tacoma fault by faults. One of these, the Nojima fault, pro- Puget Lowland, in the north-south com- zones, analysis of previous ages limits earth- duced the 1995 Mw6.9 Hyogoken Nanbu (Kobe) pressive regime of the migrating Cascadia quakes to 1200–310 cal yr B.P. The prehistory earthquake, which killed more than 6400 peo- forearc, refl ects diverse earthquake rupture clarifi es earthquake clustering in the central ple, destroyed the port of Kobe, and caused modes with variable recurrence. Stratigraphy Puget Lowland, but cannot resolve potential $100 billion in damage (Chang, 2010).
    [Show full text]
  • Land-Level Changes from a Late Holocene Earthquake in the Northern Puget Lowland, Washington
    Land-level changes from a late Holocene earthquake in the northern Puget Lowland, Washington Harvey M. Kelsey Department of Geology, Humboldt State University, Arcata, California 95521, USA Brian Sherrod U.S. Geological Survey, Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195-1310, USA Samuel Y. Johnson U.S. Geological Survey, Paci®c Science Center, 1156 High Street, Santa Cruz, California 95064, USA Shawn V. Dadisman U.S. Geological Survey, 600 4th Street, St. Petersburg, Florida 33701, USA ABSTRACT show a geomorphic and structural setting sim- An earthquake, probably generated on the southern Whidbey Island fault zone, caused ilar to that in the offshore bathymetry and 1±2 m of ground-surface uplift on central Whidbey Island ;2800±3200 yr ago. The cause seismic stratigraphy. Light detection and rang- of the uplift is a fold that grew coseismically above a blind fault that was the earthquake ing (lidar) imagery from central Whidbey Is- source. Both the fault and the fold at the fault's tip are imaged on multichannel seismic land shows a pronounced lowland in which refection pro®les in Puget Sound immediately east of the central Whidbey Island site. Hancock marsh is at the lowest point, situated Uplift is documented through contrasting histories of relative sea level at two coastal on a northeast projection of the syncline (Fig. marshes on either side of the fault. Late Holocene shallow-crustal earthquakes of Mw 5 2). Similarly, the bathymetric high in Holmes 6.5±7 pose substantial seismic hazard to the northern Puget Lowland. Harbor (between shotpoints 700 and 800, Fig.
    [Show full text]
  • Supercycle in Great Earthquake Recurrence Along the Japan Trench Over the Last 4000 Years Kazuko Usami1,5* , Ken Ikehara1, Toshiya Kanamatsu2 and Cecilia M
    Usami et al. Geosci. Lett. (2018) 5:11 https://doi.org/10.1186/s40562-018-0110-2 RESEARCH LETTER Open Access Supercycle in great earthquake recurrence along the Japan Trench over the last 4000 years Kazuko Usami1,5* , Ken Ikehara1, Toshiya Kanamatsu2 and Cecilia M. McHugh3,4 Abstract On the landward slope of the Japan Trench, the mid-slope terrace (MST) is located at a depth of 4000–6000 m. Two piston cores from the MST were analyzed to assess the applicability of the MST for turbidite paleoseismology and to fnd out reliable recurrence record of the great earthquakes along the Japan Trench. The cores have preserved records of ~ 12 seismo-turbidites (event deposits) during the last 4000 years. In the upper parts of the two cores, only the following earthquakes (magnitude M ~ 8 and larger) were clearly recorded: the 2011 Tohoku, the 1896 Sanriku, the 1454 Kyotoku, and the 869 Jogan earthquake. In the lower part of the cores, turbidites were deposited alternately in the northern and southern sites during the periods between concurrent depositional events occurring at intervals of 500–900 years. Considering the characteristics of the coring sites for their sensitivity to earthquake shaking, the con- current depositional events likely correspond to a supercycle that follows giant (M ~ 9) earthquakes along the Japan Trench. Preliminary estimations of peak ground acceleration for the historical earthquakes recorded as the turbidites imply that each rupture length of the 1454 and 869 earthquakes was over 200 km. The earthquakes related to the supercycle have occurred over at least the last 4000 years, and the cycle seems to have become slightly shorter in recent years.
    [Show full text]
  • A Stratigraphic and Microfossil Record of Coseismic Land-Level Changes and Tsunami Deposits from Old Harbor, Central Kodiak Island, Alaska
    University of Rhode Island DigitalCommons@URI Open Access Master's Theses 2018 A stratigraphic and microfossil record of coseismic land-level changes and tsunami deposits from Old Harbor, Central Kodiak Island, Alaska Greta Janigian University of Rhode Island, [email protected] Follow this and additional works at: https://digitalcommons.uri.edu/theses Recommended Citation Janigian, Greta, "A stratigraphic and microfossil record of coseismic land-level changes and tsunami deposits from Old Harbor, Central Kodiak Island, Alaska" (2018). Open Access Master's Theses. Paper 1325. https://digitalcommons.uri.edu/theses/1325 This Thesis is brought to you for free and open access by DigitalCommons@URI. It has been accepted for inclusion in Open Access Master's Theses by an authorized administrator of DigitalCommons@URI. For more information, please contact [email protected]. A STRATIGRAPHIC AND MICROFOSSIL RECORD OF COSEISMIC LAND-LEVEL CHANGES AND TSUNAMI DEPOSITS FROM OLD HARBOR, CENTRAL KODIAK ISLAND, ALASKA BY GRETA JANIGIAN A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BIOLOGICAL AND ENVIRONMENTAL SCIENCE UNIVERSITY OF RHODE ISLAND 2018 MASTER OF SCIENCE IN BIOLOGICAL AND ENVIRONMENTAL SCIENCE OF GRETA JANIGIAN APPROVED: Thesis Committee: Major Professor Simon Engelhart Brian Savage John King Tina Dura Nasser H. Zawia DEAN OF THE GRADUATE SCHOOL UNIVERSITY OF RHODE ISLAND 2018 ABSTRACT To reconstruct the paleoseismic history of Old Harbor on Kodiak Island, Alaska, we undertook exploratory coring at two coastal sites, Big Creek and Bear Terrace, 4 km and 2 km northeast of Old Harbor, respectively. We chose the longest core from Big Creek for analysis (90 cm, BC.15.02).
    [Show full text]
  • Rethinking Turbidite Paleoseismology Along the Cascadia Subduction Zone
    Rethinking turbidite paleoseismology along the Cascadia subduction zone Brian F. Atwater1, Bobb Carson2, Gary B. Griggs3, H. Paul Johnson4, and Marie S. Salmi4 1U.S. Geological Survey at University of Washington, Seattle, Washington 98195-1310, USA 2Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015-3001, USA 3Earth & Planetary Sciences Department, University of California–Santa Cruz, Santa Cruz, California 95064, USA 4School of Oceanography, University of Washington, Seattle, Washington 98195-7940, USA ABSTRACT A 130ºW 120º A stratigraphic synthesis of dozens of deep-sea cores, most of British them overlooked in recent decades, provides new insights into deep- Southern Columbia limit of 50º Fraser R. sea turbidites as guides to earthquake and tsunami hazards along the ice sheet B Cascadia subduction zone, which extends 1100 km along the Pacific Full-length coast of North America. The synthesis shows greater variability ruptures in Holocene stratigraphy and facies off the Washington coast than Waashingtonshington was recognized a quarter century ago in a confluence test for seismic Fig. triggering of sediment gravity flows. That test compared counts of 3A Holocene turbidites upstream and downstream of a deep-sea channel Columbia R. Partial junction. Similarity in the turbidite counts among seven core sites pro- BFZ Cascadia ruptures vided evidence that turbidity currents from different submarine can- Channel Oregon yons usually reached the junction around the same time, as expected Seaward of widespread seismic triggering. The fuller synthesis, however, shows edge of distinct differences between tributaries, and these differences suggest megathrust California sediment routing for which the confluence test was not designed. The 40ºN synthesis also bears on recent estimates of Cascadia earthquake mag- PACIFIC OCEAN 19 4 10 10 nitudes and recurrence intervals.
    [Show full text]
  • Paleoseismology: Why Can’T Earthquakes Keep on Schedule? Robert S
    Paleoseismology: Why can’t earthquakes keep on schedule? Robert S. Yeats Earth Consultants International, 150 El Camino Real, Suite 212, Tustin, California 92780, and Oregon State University, Corvallis, Oregon 97331, USA Our neighbors and the media ask us when the next large earthquake is et al. (this issue, p. 855), the slip rate on the western part of the Garlock due. In our response, we follow Shakespeare: “what’s past is prologue.” fault (California), based on geodesy is nearly half the rate based on late But projecting the past into the future is tricky because earthquakes, unlike Quaternary geology. On the other hand, the geodetically based slip rate tides and Halley’s comet, don’t follow a regular schedule, as shown by across the eastern California shear zone (ECSZ) in the Mojave Desert 1) the earliest multiple-event paleoseismological studies at Pallett Creek is close to twice the rate based on late Quaternary geology. Weldon on the San Andreas fault (Sieh, 1978), 2) trenching studies on the Wasatch et al. (2004) have shown that the long-term slip rate on the San Andreas fault (Machette et al., 1992) and elsewhere, and 3) analysis of a 50,000-yr- fault at Wrightwood is considerably faster than the geodetic rate there, long record of lake sediments in the Dead Sea graben (Marco et al., 1996). although the geodetic rate is in agreement with the geologically deter- Lack of periodic behavior in earthquakes should not surprise us because mined rate for the past 1100 yr. Earth’s crust is complicated, with many unknowns at depths where we How does one take these observations to the next level to improve cannot observe directly.
    [Show full text]
  • IAEA TECDOC SERIES the Contribution of Palaeoseismology to Seismic Hazard for Nuclearassessment in Site Evaluation Installations
    208 pgs = 10.81 mm IAEA-TECDOC-1767 IAEA-TECDOC-1767 IAEA TECDOC SERIES The Contribution of Palaeoseismology to Seismic Hazard Assessment in Site Evaluation for Nuclear Installations Assessment in Site Evaluation for Nuclear to Seismic Hazard The Contribution of Palaeoseismology IAEA-TECDOC-1767 The Contribution of Palaeoseismology to Seismic Hazard Assessment in Site Evaluation for Nuclear Installations International Atomic Energy Agency Vienna ISBN 978–92–0–105415–9 ISSN 1011–4289 @ IAEA SAFETY STANDARDS AND RELATED PUBLICATIONS IAEA SAFETY STANDARDS Under the terms of Article III of its Statute, the IAEA is authorized to establish or adopt standards of safety for protection of health and minimization of danger to life and property, and to provide for the application of these standards. The publications by means of which the IAEA establishes standards are issued in the IAEA Safety Standards Series. This series covers nuclear safety, radiation safety, transport safety and waste safety. The publication categories in the series are Safety Fundamentals, Safety Requirements and Safety Guides. Information on the IAEAs safety standards programme is available at the IAEA Internet site http://www-ns.iaea.org/standards/ The site provides the texts in English of published and draft safety standards. The texts of safety standards issued in Arabic, Chinese, French, Russian and Spanish, the IAEA Safety Glossary and a status report for safety standards under development are also available. For further information, please contact the IAEA at PO Box 100, 1400 Vienna, Austria. All users of IAEA safety standards are invited to inform the IAEA of experience in their use (e.g.
    [Show full text]