@article {2776,
	title = {Identifying the Greatest Earthquakes of the Past 2000 Years at the Nehalem River Estuary, Northern Oregon Coast, USA},
	journal = {Open Quaternary},
	volume = {6},
	year = {2020},
	month = {Feb-01-2021},
	abstract = {We infer a history of three great megathrust earthquakes during the past 2000 years at the Nehalem River estuary based on the lateral extent of sharp (<=3 mm) peat-mud stratigraphic contacts in cores and outcrops, coseismic subsidence as interpreted from fossil diatom assemblages and reconstructed with foraminiferal assemblages using a Bayesian transfer function, and regional correlation of 14C-modeled ages for the times of subsidence. A subsidence contact from 1700 CE (contact A), sometimes overlain by tsunami-deposited sand, can be traced over distances of 7 km. Contacts B and D, which record subsidence during two earlier megathrust earthquakes, are much less extensive but are traced across a 700-m by 270-m tidal marsh. Although some other Cascadia studies report evidence for an earthquake between contacts B and D, our lack of extensive evidence for such an earthquake may result from the complexities of preserving identifiable evidence of it in the rapidly shifting shoreline environments of the lower river and bay. Ages (95\% intervals) and subsidence for contacts are: A, 1700 CE (1.1 {\textpm} 0.5 m); B, 942{\textendash}764 cal a BP (0.7 {\textpm} 0.4 m and 1.0 m {\textpm} 0.4 m); and D, 1568{\textendash}1361 cal a BP (1.0 m {\textpm} 0.4 m). Comparisons of contact subsidence and the degree of overlap of their modeled ages with ages for other Cascadia sites are consistent with megathrust ruptures many hundreds of kilometers long. But these data cannot conclusively distinguish among different types or lengths of ruptures recorded by the three great earthquake contacts at the Nehalem River estuary.},
	keywords = {Bayesian transfer function, Cascadia subduction zone, Coseismic subsidence, earthquake hazards, Paleoseismology, salt-marsh stratigraphy, Sea-level changes, tidal foraminifera and diatoms},
	doi = {10.5334/oq.70},
	url = {http://www.openquaternary.com/articles/10.5334/oq.70/},
	author = {Nelson, Alan R. and Hawkes, Andrea D. and Sawai, Yuki and Engelhart, Simon E. and Witter, Rob and Grant-Walter, Wendy C. and Bradley, Lee-Ann and Dura, Tina and Cahill, Niamh and Horton, Ben}
}
@article {2597,
	title = {Differences in coastal subsidence in southern Oregon (USA) during at least six prehistoric megathrust earthquakes},
	journal = {Quaternary Science Reviews},
	volume = {142},
	year = {2016},
	month = {Jan-06-2016},
	pages = {143 - 163},
	abstract = {Stratigraphic, sedimentologic (including CT 3D X-ray tomography scans), foraminiferal, and radiocarbon analyses show that at least six of seven abrupt peat-to-mud contacts in cores from a tidal marsh at Talbot Creek (South Slough, Coos Bay), record sudden subsidence (relative sea-level rise) during great megathrust earthquakes at the Cascadia subduction zone. Data for one contact are insufficient to infer whether or not it records a great earthquake{\textemdash}it may also have formed through local, non-seismic, hydrographic processes. To estimate the amount of subsidence marked by each contact, we expanded a previous regional modern foraminiferal dataset to 174 samples from six Oregon estuaries. Using a transfer function derived from the new dataset, estimates of coseismic subsidence across the six earthquake contacts vary from 0.31 m to 0.75 m. Comparison of subsidence estimates for three contacts in adjacent cores shows within-site differences of <=0.10 m, about half the {\textpm}0.22 m error, although some estimates may be minimums due to uncertain ecological preferences for Balticammina pseudomacrescens in brackish environments and almost monospecific assemblages of Miliammina fusca on tidal flats. We also account for the influence of taphonomic processes, such as infiltration of mud with mixed foraminiferal assemblages into peat, on subsidence estimates. Comparisons of our subsidence estimates with values for correlative contacts at other Oregon sites suggest that some of our estimates are minimums and that Cascadia{\textquoteright}s megathrust earthquake ruptures have been heterogeneous over the past 3500 years.},
	keywords = {Cascadia subduction zone, Coseismic subsidence, Megathrust earthquakes, Paleoseismology, Salt-marsh foraminifera, Sea-level change, Transfer functions},
	issn = {02773791},
	doi = {10.1016/j.quascirev.2016.04.017},
	url = {https://doi.org/10.1016/j.quascirev.2016.04.017},
	author = {Milker, Yvonne and Nelson, Alan R. and Horton, Benjamin P. and Engelhart, Simon E. and Bradley, Lee-Ann and Witter, Robert C.}
}
@article {2591,
	title = {Diverse rupture modes for surface-deforming upper-plate earthquakes in the southern Puget Lowland of Washington State},
	journal = {Geosphere},
	volume = {10},
	year = {2014},
	month = {Jan-01-2014},
	pages = {769},
	abstract = {Earthquake prehistory of the southern Puget Lowland, in the north-south compressive regime of the migrating Cascadia forearc, reflects diverse earthquake rupture modes with variable recurrence. Stratigraphy and Bayesian analyses of previously reported and new 14C ages in trenches and cores along backthrust scarps in the Seattle fault zone restrict a large earthquake to 1040{\textendash}910 cal yr B.P. (2σ), an interval that includes the time of the M 7{\textendash}7.5 Restoration Point earthquake. A newly identified surface-rupturing earthquake along the Waterman Point backthrust dates to 940{\textendash}380 cal yr B.P., bringing the number of earthquakes in the Seattle fault zone in the past 3500 yr to 4 or 5. Whether scarps record earthquakes of moderate (M 5.5{\textendash}6.0) or large (M 6.5{\textendash}7.0) magnitude, backthrusts of the Seattle fault zone may slip during moderate to large earthquakes every few hundred years for periods of 1000{\textendash}2000 yr, and then not slip for periods of at least several thousands of years. Four new fault scarp trenches in the Tacoma fault zone show evidence of late Holocene folding and faulting about the time of a large earthquake or earthquakes inferred from widespread coseismic subsidence ca. 1000 cal yr B.P.; 12 ages from 8 sites in the Tacoma fault zone limit the earthquakes to 1050{\textendash}980 cal yr B.P. Evidence is too sparse to determine whether a large earthquake was closely predated or postdated by other earthquakes in the Tacoma basin, but the scarp of the Tacoma fault was formed by multiple earthquakes. In the northeast-striking Saddle Mountain deformation zone, along the western limit of the Seattle and Tacoma fault zones, analysis of previous ages limits earthquakes to 1200{\textendash}310 cal yr B.P. The prehistory clarifies earthquake clustering in the central Puget Lowland, but cannot resolve potential structural links among the three Holocene fault zones.},
	issn = {1553040X},
	doi = {10.1130/GES00967.110.1130/GES00967.S1},
	url = {https://pubs.geoscienceworld.org/geosphere/article/10/4/769-796/132175},
	author = {Nelson, Alan R. and Personius, Stephen F. and Sherrod, Brian L. and Kelsey, Harvey M. and Johnson, Samuel Y. and Bradley, Lee-Ann and Wells, Ray E.}
}
@article {2593,
	title = {Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)},
	journal = {Geophysical Research Letters},
	volume = {41},
	year = {2014},
	month = {Apr-04-2015},
	pages = {2289 - 2296},
	abstract = {We report stratigraphic evidence of land-level change and tsunami inundation along the Alaska-Aleutian megathrust during prehistoric and historical earthquakes west of Kodiak Island. On Sitkinak Island, cores and tidal outcrops fringing a lagoon reveal five sharp lithologic contacts that record coseismic land-level change. Radiocarbon dates, 137Cs profiles, computerized tomography scans, and microfossil assemblages are consistent with rapid uplift circa 290{\textendash}0, 520{\textendash}300, and 1050{\textendash}790 cal yr B.P. and subsidence in A.D. 1964 and circa 640{\textendash}510 cal yr B.P. Radiocarbon, 137Cs, and 210Pb ages bracketing a sand bed traced 1.5 km inland and evidence for sudden uplift are consistent with Russian accounts of an earthquake and tsunami in A.D. 1788. The mixed uplift and subsidence record suggests that Sitkinak Island sits above a nonpersistent boundary near the southwestern limit of the A.D. 1964 Mw 9.2 megathrust rupture.},
	doi = {10.1002/2014GL059380},
	url = {http://doi.wiley.com/10.1002/2014GL059380},
	author = {Briggs, Richard W. and Engelhart, Simon E. and Nelson, Alan R. and Dura, Tina and Kemp, Andrew C. and Haeussler, Peter J. and Corbett, D. Reide and Angster, Stephen J. and Bradley, Lee-Ann}
}
@article {291,
	title = {Fragmentary Evidence of Great-Earthquake Subsidence during Holocene Emergence, Valdivia Estuary, South Central Chile},
	journal = {Bulletin of the Seismological Society of America},
	volume = {99},
	year = {2009},
	note = {id: 2020; PT: J; UT: WOS:000266181100006},
	pages = {71-86},
	abstract = {A reconnaissance of Holocene stratigraphy beneath fringing marshes of the Valdivia estuary, where an M 9.5 earthquake caused 1-2 m of regional coseismic subsidence in 1960, shows only fragmentary evidence of prehistoric coseismic subsidence. In most of the 150 hand-driven cores that were examined, a distinct unconformity separates 0.5-1.5 m of late Holocene tidal and floodplain mud, peat, and sand from underlying middle Holocene subtidal mud and sand. At the Las Coloradas site, where stratigraphy is best preserved, two A horizons of marsh and meadow soils abruptly overlain by sand and mud probably record coseismic subsidence shortly followed by tsunamis. The amount of subsidence during the earthquakes proved difficult to reconstruct with a diatom transfer function because of differences between modern and fossil diatom assemblages. Maximum (14)C ages on macrofossils from the two A horizons at the Las Coloradas site of 1.7-1.3 ka and 2.7-1.7 ka allow correlation of the younger horizon with either of two of six (14)C-dated A horizons buried by tsunami sand or post-tsunami tidal sand 200 km to the south at Maullin, and with a lake-wide mass wasting event in Lago Puyehue, 100 km to the southeast. Tidal records of prehistoric coseismic subsidence at Valdivia are scarce because of a sea-level fall of 3-8 m over the past 6000 years, erosion of marsh and meadow soils during subsidence-induced flooding of the estuary, and largely complete land-level recovery during cycles of coseismic subsidence and postseismic uplift.},
	issn = {0037-1106},
	doi = {10.1785/0120080103},
	author = {Nelson, Alan R. and Kashima, Kaoru and Bradley, Lee-Ann}
}
