@article {154, title = {Stratigraphic evidence for an early Holocene earthquake in Aceh, Indonesia}, journal = {Quaternary Science Reviews}, volume = {54}, year = {2012}, note = {id: 2139}, pages = {142-151}, abstract = {The Holocene stratigraphy of the coastal plain of the Aceh Province of Sumatra contains 6 m of sediment with three regionally consistent buried soils above pre-Quaternary bedrock or pre-Holocene unconsolidated sediment. Litho-, bio-, and chronostratigraphic analyses of the lower buried soil reveals a rapid change in relative sea-level caused by coseismic subsidence during an earlyHolocene megathrust earthquake. Evidence for paleoseismic subsidence is preserved as a buried mangrove soil, dominated by a pollen assemblage of Rhizophora and/or Bruguiera/Ceriops taxa. The soil is abruptly overlain by a thin tsunami sand. The sand contains mixed pollen and abraded foraminiferal assemblages of both offshore and onshore environments. The tsunami sand grades upward into mud that contains both well-preserved foraminifera of intertidal origin and individuals of the gastropod Cerithidea cingulata. Radiocarbon ages from the pre- and post-seismic sedimentary sequences constrain the paleoearthquake to 6500{\textendash}7000 cal. yrs. BP. We use micro-and macrofossil data to determine the local paleoenvironment before and after the earthquake. We estimate coseismic subsidence to be 0.45 {\textpm} 0.30 m, which is comparable to the 0.6 m of subsidence observed during the 2004 Aceh{\textendash}Andaman earthquake on Aceh{\textquoteright}s west coast.}, doi = {10.1016/j.quascirev.2012.03.011}, author = {Grand Pre, C. and Horton, B. P. and Kelsey, H. M. and Rubin, C. M. and Hawkes, A. D. and Daryono, M. and Rosenberg, G. and Culver, S. J.} } @article {652, title = {Great earthquakes of variable magnitude at the Cascadia subduction zone}, journal = {Quaternary Research}, volume = {65}, year = {2006}, note = {046pgTimes Cited:70Cited References Count:66}, month = {May}, pages = {354-365}, abstract = {Comparison of histories of great earthquakes and accompanying tsunamis at eight coastal sites suggests plate-boundary ruptures of varying length, implying great earthquakes of variable magnitude at the Cascadia subduction zone. Inference of rupture length relies on degree of overlap on radiocarbon age ranges for earthquakes and tsunamis, and relative amounts of coseismic subsidence and heights of tsunamis. Written records of a tsunami in Japan provide the most conclusive evidence for rupture of much of the plate boundary during the earthquake of 26 January 1700. Cascadia stratigraphic evidence dating from about 1600 cal yr B.P., similar to that for the 1700 earthquake, implies a similarly long rupture with substantial subsidence and a high tsunami. Correlations are consistent with other long ruptures about 1350 cal yr B.P., 2500 cal yr B.P., 3400 cal yr B.P., 3800 cal yr B.P., 4400 cal yr B.P., and 4900 cal yr B.P. A rupture about 700-1100 cal yr B.P. was limited to the northern and central parts of the subduction zone, and a northern rupture about 2900 cal yr B.P. may have been similarly limited. Times of probable short ruptures in southern Cascadia include about I 100 cal yr B.P., 1700 cal yr B.P., 3200 cal yr B.P., 4200 cal yr B.P., 4600 cal yr B.P., and 4700 cal yr B.P. Rupture patterns suggest that the plate boundary in northern Cascadia usually breaks in long ruptures during the greatest earthquakes. Ruptures in southernmost Cascadia vary in length and recurrence intervals more than ruptures in northern Cascadia. Published by University of Washington.}, issn = {0033-5894}, doi = {10.1016/j.yqres.2006.02.009}, author = {Nelson, A. R. and Kelsey, H. M. and Witter, R. C.} } @article {690, title = {Tsunami history of an Oregon coastal lake reveals a 4600 yr record of great earthquakes on the Cascadia subduction zone}, journal = {Geological Society of America Bulletin}, volume = {117}, year = {2005}, note = {938hsTimes Cited:103Cited References Count:73}, month = {Jul-Aug}, pages = {1009-1032}, abstract = {Bradley Lake, on the southern Oregon coastal plain, records local tsunamis and seismic shaking on the Cascadia subduction zone over the last 7000 yr. Thirteen marine incursions delivered landward-thinning sheets of sand to the lake from nearshore, beach, and dune environments to the west. Following each incursion, a slug of marine water near the bottom of the freshwater take instigated a few-year-to-several-decade period of a brackish (<= 4 parts per thousand salinity) lake. Four additional disturbances without marine incursions destabilized sideslopes and bottom sediment, producing a suspension deposit that blanketed the lake bottom.Considering the magnitude and duration of the disturbances necessary to produce Bradley Lake{\textquoteright}s marine incursions, a local tsunami generated by a great earthquake on the Cascadia subduction zone is the only accountable mechanism. Extreme ocean levels must have been at least 5-8 m above sea level, and the cumulative duration of each marine incursion must have been at least 10 min. Disturbances without marine incursions require seismic shaking as well.Over the 4600 yr period when Bradley Lake was an optimum tsunami recorder, tsunamis from Cascadia plate-boundary earthquakes came in clusters. Between 4600 and 2800 cal yr B.P., tsunamis occurred at the average frequency of similar to 3-4 every 1000 yr. Then, starting similar to 2800 cal yr B.P., there was a 930-1260 yr interval with no tsunamis. That gap was followed by a similar to 1000 yr period with 4 tsunamis. In the last millennium, a 670-750 yr gap preceded the A.D. 1700 earthquake and tsunami. The A.D. 1700 earthquake may be the first of a new cluster of plate-boundary earthquakes and accompanying tsunamis.Local tsunamis entered Bradley Lake an average of every 390 yr, whereas the portion of the Cascadia plate boundary that underlies Bradley Lake ruptured in a great earthquake less frequently, about once every 500 yr. Therefore, the entire length of the subduction zone does not rupture in every earthquake, and Bradley Lake has recorded earthquakes caused by rupture along the entire length of the Cascadia plate boundary as well as earthquakes caused by rupture of shorter segments of the boundary. The tsunami record from Bradley Lake indicates that at times, most recently similar to 1700 yr B.P., overlapping or adjoining segments of the Cascadia plate boundary ruptured within decades of each other.}, issn = {0016-7606}, doi = {10.1130/B25452.1}, author = {Kelsey, H. M. and Nelson, A. R. and Hemphill-Haley, E. and Witter, R. C.} } @article {687, title = {Holocene fault scarps near Tacoma, Washington, USA}, journal = {Geology}, volume = {32}, year = {2004}, note = {765ehTimes Cited:50Cited References Count:22}, month = {Jan}, pages = {9-12}, abstract = {Airborne laser mapping confirms that Holocene active faults traverse the Puget Sound metropolitan area, northwestern continental United States. The mapping, which detects forest-floor relief of as little as 15 cm, reveals scarps along geophysical lineaments that separate areas of Holocene uplift and subsidence. Along one such line of scarps, we found that a fault warped the ground surface between A.D. 770 and 1160. This reverse fault, which projects through Tacoma, Washington, bounds the southern and western sides of the Seattle uplift. The northern flank of the Seattle uplift is bounded by a reverse fault beneath Seattle that broke in A.D. 900-930. Observations of tectonic scarps along the Tacoma fault demonstrate that active faulting with associated surface rupture and ground motions pose a significant hazard in the Puget Sound region.}, issn = {0091-7613}, doi = {10.1130/G19914.1}, author = {Sherrod, B. L. and Brocher, T. M. and Weaver, C. S. and Bucknam, R. C. and Blakely, R. J. and Kelsey, H. M. and Nelson, A. R. and Haugerud, R.} } @article {2064, title = {The Catfish Lake scarp: preliminary field data and implications for earthquake hazards posed by the Tacoma fault}, journal = {U. S. Geological Survey Open-File Report}, volume = {03-0455}, year = {2003}, note = {id: 430}, month = {2003}, pages = {11 p.}, author = {Sherrod, B. L. and Nelson, A. R. and Kelsey, H. M. and Brocher, T. M. and Blakely, R. J. and Weaver, C. S. and Rountree, N. K. and Rhea, S. and Jackson, B. S.} } @article {733, title = {Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington}, journal = {Geological Society of America Bulletin}, volume = {115}, year = {2003}, note = {740qwTimes Cited:41Cited References Count:53}, month = {Nov}, pages = {1388-1403}, abstract = {Five trenches across a Holocene fault scarp yield the first radiocarbon-measured earthquake recurrence intervals for a crustal fault in western Washington. The scarp, the first to be revealed by laser imagery, marks the Toe Jam Hill fault, a north-dipping backthrust to the Seattle fault. Folded and faulted strata, liquefaction features, and forest soil A horizons buried by hanging-wall-collapse colluvium record three, or possibly four, earthquakes between 2500 and 1000 yr ago. The most recent earthquake is probably the 1050-1020 cal. (calibrated) yr B.P. (A.D. 900930) earthquake that raised marine terraces and triggered a tsunami in Puget Sound. Vertical deformation estimated from strati-graphic and surface offsets at trench sites suggests late Holocene earthquake magnitudes near M7, corresponding to surface ruptures >36 km long. Deformation features recording poorly understood latest Pleistocene earthquakes suggest that they were smaller than late Holocene earthquakes. Postglacial earthquake recurrence intervals based on 97 radiocarbon ages, most on detrital charcoal, range from similar to12,000 yr to as little as a century or less; corresponding fault-slip rates are 0.2 mm/ yr for the past 16,000 yr and 2 mm/yr for the past 2500 yr. Because the Toe Jam Hill fault is a backthrust to the Seattle fault, it may not have ruptured during every earthquake on the Seattle fault. But the earthquake history of the Toe Jam Hill fault is at least a partial proxy for the history of the rest of the Seattle fault zone.}, issn = {0016-7606}, doi = {10.1130/B25262.1}, author = {Nelson, A. R. and Johnson, S. Y. and Kelsey, H. M. and Wells, R. E. and Sherrod, B. L. and Pezzopane, S. K. and Bradley, L. A. and Koehler, R. D. and Bucknam, R. C.} } @article {1357, title = {Maps and data from a trench investigation of the Utsalady Point fault, Whidbey Island, Washington}, year = {2003}, note = {id: 996}, month = {2003}, author = {Johnson, S. Y. and Nelson, A. R. and Personius, S. F. and Wells, R. E. and Kelsey, H. M. and Sherrod, B. L. and Okumura, K. and Koehler, R., III and Witter, R. C. and Bradley, L. A. and Harding, D. J.} } @article {2107, title = {Field and laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington}, journal = {U.S. Geological Survey Open-File Report}, volume = {02-60}, year = {2002}, note = {id: 428}, month = {2002}, pages = {37 p.}, author = {Nelson, A. R. and Johnson, S. Y. and Wells, R. E. and Kelsey, H. M. and Pezzopane, S. K. and Sherrod, B. L. and Bradley, L. A. and Iii, Koehler R. D. and Bucknam, R. C. and Haugerud, R. A. and LaPrade, W. T.} } @article {2106, title = {Field and Laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington}, journal = {U.S. Geological Survey Open-File Report 02-60}, year = {2002}, note = {id: 259}, month = {2002}, pages = {2 plates and 37 pages}, author = {Nelson, A. R. and Johnson, S. Y. and Wells, R. E. and Pezzopane, S. K. and Kelsey, H. M. and Sherrod, B. L. and Bradley, L. A. and Koehler, R. D., III and Bucknam, R. C. and Haugerud, R. A. and LaPrade, W. T.} } @article {805, title = {Optical dating of tsunami-laid sand from an Oregon coastal lake}, journal = {Quaternary Science Reviews}, volume = {20}, year = {2001}, note = {500nqTimes Cited:24Cited References Count:39}, month = {Dec}, pages = {1915-1926}, abstract = {Optical ages for five samples of tsunami-laid sand from an Oregon coastal lake were determined using an infrared optical-dating method on K-feldspar separates and, as a test of accuracy, compared to ages determined by AMS C-14 dating or detrital plant fragments found in the same beds. Two optical ages were about 20\% younger than calibrated C-14 ages of about 3.1 and 4.3 ka. Correction of the optical ages using measured anomalous fading rates brings them into agreement with the C-14 ages. The approach used holds significant promise for improving the accuracy of infrared optical-dating methods.Luminescence data for the other three samples result in optical age limits much greater than the C-14 ages. These data provide a textbook demonstration of the correlation between scatter in the luminescence intensity of individual sample aliquots and their normalization values that is expected when the samples contain sand grains not adequately exposed to daylight just prior to or during deposition and burial. Thus, the data for these three samples suggest that the tsunamis eroded young and old sand deposits before dropping the sand in the lake. (C) 2001 Elsevier Science Ltd. All rights reserved.}, issn = {0277-3791}, doi = {10.1016/S0277-3791(01)00043-9}, author = {Ollerhead, J. and Huntley, D. J. and Nelson, A. R. and Kelsey, H. M.} } @conference {1728, title = {OxCal analyses and varve-based sedimentation rates constrain the times of 14C-dated tsunamis in southern Oregon}, booktitle = {Abstract for Geological Society of America Penbrose Conference on Great Cascadia Earthquake Tricentennial Seaside}, year = {2000}, note = {id: 1405}, month = {2000}, pages = {87}, address = {Seaside, Oregon}, author = {Nelson, A. R. and Kelsey, H. M. and Hemphill-Haley, Eileen and Witter, R. C.} } @article {2181, title = {Postglacial and Late Holocene earthquakes on the Toe Jam strand of the Seattle fault, Bainbridge Island Washington}, journal = {Geological Society of America Abstracts with Programs}, volume = {32}, year = {2000}, note = {id: 258}, month = {2000}, pages = {A-58}, author = {Nelson, A. R. and Johnson, S. Y. and Pezzopane, S. K. and Wells, R. E. and Kelsey, H. M. and Sherrod, B. L. and Koehler, R. D. and Bradley, L. A. and Bucknam, R. C. and LaPrade, W. T. and Cox, J. W. and Narwold, C. F.} } @article {2218, title = {Holocene surface faulting in the Seattle fault zone, Bainbridge Island, Washington}, journal = {Seismological Research Letters}, volume = {70}, year = {1999}, note = {id: 1404}, month = {1999}, pages = {233}, author = {Nelson, A. R. and Pezzopane, S. K. and Bucknam, R. C. and Koehler, R. D. and Narwold, C. F. and Kelsey, H. M. and Sherrod, B. L. and LaPrade, W. T. and Wells, R. E. and Johnson, S. Y.} }