Earthquake hazards in the Pacific Northwest: An overview

Rogers, A. M.; Walsh, Timothy J.; Kockelman, William J.; Priest, George R.

doi:10.3133/ofr91441o

Cited by 5 publications

(5 citation statements)

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“…The heavily populated Puget Lowland region (Figure 1) has been the subject of an increasing number of scientific investigations designed to clarify the nature of its seismic hazards. The lowland has had a large number of historical earthquakes relative to its surrounding areas, and most of the larger events have been within the subducting Juan de Fuca plate [ Ludwin et al , 1991; Rogers et al , 1996]. Recent geologic investigations, however, have documented major prehistoric earthquakes in the overriding North American plate, in particular along the Seattle fault [ Bucknam et al , 1992; Nelson et al , 1999].…”

Section: Introductionmentioning

confidence: 99%

Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

et al. 2002

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[1] Paleomagnetic results from Pleistocene sedimentary deposits in the central Puget Lowland indicate that the region has experienced widespread deformation within the last 780 kyr. Three oriented samples were collected from unaltered fine-grained sediments mostly at sea level to determine the magnetostratigraphy at 83 sites. Of these, 47 have normal, 18 have reversed, and 18 have transitional (8 localities) polarities. Records of reversed-to normal-polarity transitions of the geomagnetic field were found in thick sections of silt near the eastern end of the Tacoma Narrows Bridge, and again at Wingehaven Park near the northern tip of Vashon Island. The transitional horizons, probably related to the Bruhnes-Matuyama reversal, apparently fall between previously dated Pleistocene sediments at the Puyallup Valley type section (all reversed-polarity) to the south and the Whidbey Island type section (all normal-polarity) to the north. The samples, in general, are of sufficient quality to record paleosecular variation (PSV) of the geomagnetic field, and a statistical technique is used to correlate horizons with significant agreement in their paleomagnetic directions. Our data are consistent with the broad structures of the Seattle uplift inferred at depth from seismic reflection, gravity, and aeromagnetic profiles, but the magnitude of vertical adjustments is greatly subdued in the Pleistocene deposits.

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Section: Introductionmentioning

confidence: 99%

Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

et al. 2002

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“… a Chleborad and Schuster (1990) and Rogers et al (1998); b Tinsley et al (1998); c Stewart et al (1996); d Chu et al (2004); e Bray et al (2001); f Holzer et al (2005); g Cao et al (2010); h McCrink et al (2011); i Geyin et al (2020); j Moss et al (2015); k Zimmaro et al (2020). …”

Section: Empirical Datamentioning

confidence: 99%

A latent Gaussian process model for the spatial distribution of liquefaction manifestation

et al. 2023

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This paper presents a model for distributing zones of liquefaction and nonliquefaction for use in regional liquefaction risk analysis. There are two broad methodologies that have been used to evaluate liquefaction risk on the regional scale: (a) application of site-specific procedures using soil properties inferred from geology, or (b) application of geospatial proxies for liquefaction. The first approach will tend to predict similar liquefaction probabilities across broad areas with similar geology, water table depths, and shaking intensities. The second approach yields the probability of liquefaction, which can be interpreted as the portion of the area affected by liquefaction ([Formula: see text]). Neither approach, however, gives an informed prediction of the spatial distribution of liquefaction and the resulting displacements, which are particularly important for assessments of seismic risk for spatially distributed infrastructure systems. We propose a methodology for incorporating spatial correlation into a geospatial proxy for liquefaction to create maps of liquefaction and nonliquefaction for a given earthquake scenario. First, we describe a latent Gaussian process that is assumed to govern the spatial distribution of liquefaction. Next, a database of empirical observations of liquefaction is used to obtain the coefficients that describe that latent Gaussian process. The proposed model yields random realizations of maps of liquefaction and nonliquefaction conditioned on a map of [Formula: see text]. Such maps can be used to constrain the area over which displacements are estimated using soil properties inferred from geology and are therefore a critical component in reducing bias in assessments of liquefaction risk at the regional scale.

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“…We anticipate that nearly all floodplain wetland communities would first experience die‐off due to frequent inundation after land subsidence and increased tidal range; these results are consistent with the observations of “ghost trees” that died in 1700 and are still found in estuaries of the Pacific Northwest (Atwater, 1987). In the lower estuary, sand deposition on subsided marsh planforms could result in higher marsh elevation than predicted by co‐seismic subsidence alone (Rogers, 1996). Nonetheless, our bathymetric and habitat change scenario will likely be modified by both the acute erosion/deposition caused by the tsunami and longer term morphodynamics responses.…”

Section: Habitat Successionmentioning

confidence: 99%

Impacts of a Cascadia Subduction Zone Earthquake on Water Levels and Wetlands of the Lower Columbia River and Estuary

Brand

Diefenderfer

O’Connor

et al. 2023

Geophysical Research Letters

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Subsidence after a subduction zone earthquake can cause major changes in estuarine bathymetry. Here, we quantify the impacts of earthquake‐induced subsidence on hydrodynamics and habitat distributions in a major system, the lower Columbia River Estuary, using a hydrodynamic and habitat model. Model results indicate that coseismic subsidence increases tidal range, with the smallest changes at the coast and a maximum increase of ∼10% in a region of topographic convergence. All modeled scenarios reduce intertidal habitat by 24%–25% and shifts ∼93% of estuarine wetlands to lower‐elevation habitat bands. Incorporating dynamic effects of tidal change from subsidence yields higher estimates of remaining habitat by multiples of 0–3.7, dependent on the habitat type. The persistent tidal change and chronic habitat disturbance after an earthquake poses strong challenges for estuarine management and wetland restoration planning, particularly when coupled with future sea‐level rise effects.

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Earthquake hazards in the Pacific Northwest: An overview

Cited by 5 publications

References 0 publications

Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

Magnetostratigraphy, paleomagnetic correlation, and deformation of Pleistocene deposits in the south central Puget Lowland, Washington

A latent Gaussian process model for the spatial distribution of liquefaction manifestation

Impacts of a Cascadia Subduction Zone Earthquake on Water Levels and Wetlands of the Lower Columbia River and Estuary

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