ASSESSING THE IMPACT OF COSEISMIC LANDSLIDES DURING THE AD 1700 CASCADIA SUBDUCTION ZONE MEGATHRUST EARTHQUAKE ALONG THE COASTLINE OF THE PACIFIC NORTHWEST (USA)

2016 ◽  
Author(s):  
Sean Richard LaHusen ◽  
◽  
Alison R. Duvall ◽  
Alex R. Grant ◽  
Joseph Wartman
Keyword(s):  
Subduction Zone ◽  
Pacific Northwest ◽  
Cascadia Subduction Zone ◽  
Megathrust Earthquake ◽  
Coseismic Landslides ◽  
The Pacific ◽  
The Impact

scholarly journals Toward an Integrative Geological and Geophysical View of Cascadia Subduction Zone Earthquakes

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Maureen A.L. Walton ◽  
Lydia M. Staisch ◽  
Tina Dura ◽  
Jessie K. Pearl ◽  
Brian Sherrod ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Pacific Northwest ◽  
Current Knowledge ◽  
Cascadia Subduction Zone ◽  
Annual Review ◽  
Publication Date ◽  
Data Sets ◽  
Megathrust Earthquake ◽  
Megathrust Earthquakes ◽  
National Boundaries

The Cascadia subduction zone (CSZ) is an exceptional geologic environment for recording evidence of land-level changes, tsunamis, and ground motion that reveals at least 19 great megathrust earthquakes over the past 10 kyr. Such earthquakes are among the most impactful natural hazards on Earth, transcend national boundaries, and can have global impact. Reducing the societal impacts of future events in the US Pacific Northwest and coastal British Columbia, Canada, requires improved scientific understanding of megathrust earthquake rupture, recurrence, and corresponding hazards. Despite substantial knowledge gained from decades of research, large uncertainties remain about the characteristics and frequencies of past CSZ earthquakes. In this review, we summarize geological, geophysical, and instrumental evidence relevant to understanding megathrust earthquakes along the CSZ and associated uncertainties. We discuss how the evidence constrains various models of great megathrust earthquake recurrence in Cascadia and identify potential paths forward for the earthquake science community. ▪ Despite outstanding geologic records of past megathrust events, large uncertainty of the magnitude and frequency of CSZ earthquakes remains. ▪ This review outlines current knowledge and promising future directions to address outstanding questions on CSZ rupture characteristics and recurrence. ▪ Integration of diverse data sets with attention to the geologic processes that create different records has potential to lead to major progress. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 49 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Ground-Motion Attenuation Equations for Earthquakes on the Cascadia Subduction Zone

1991 ◽  
Vol 7 (2) ◽  
pp. 201-236 ◽  
Author(s):  
C. B. Crouse
Keyword(s):  
Data Base ◽  
Subduction Zone ◽  
Ground Motion ◽  
Pacific Northwest ◽  
Puget Sound ◽  
Response Spectra ◽  
Cascadia Subduction Zone ◽  
Regression Equations ◽  
Median Response ◽  
The Pacific

An extensive ground-motion data base was compiled for earthquakes occurring in subduction zones considered representative of the Cascadia subduction zone in the Pacific Northwest. The attenuation characteristics of horizontal peak ground accelerations (PGA) and 5 percent damped pseudovelocity (PSV) were studied for various subsets of the total data base. These data suggested that the PGA tend to saturate at small source-to-site distances and large magnitudes. When unprocessed data were added to the data base, the attenuation of PGA with distance was found to be greater than the attenuation observed for the processed data only, a result which was attributed to the selection of only the stronger motion records for processing. The results of the data analysis were used to establish the proper form of regression equations for estimating PGA and PSV at firm-soil sites in the Pacific Northwest. A total of 697 PGA components and 235 PSV components were selected for the regressions. The resulting equation for estimating PGA in gals was ln (PGA) = 6.36 + 1.76M − 2.73 ln (R + 1.58 exp (0.608M) + 0.00916h, σ=0.773 where M is moment magnitude, R is center-of-energy-release distance in km, h is focal depth in km, and σ is the standard error of ln (PGA). Although σ was relatively large, the residuals from the regressions appeared to decrease with increasing M and R. The results of the PSV regressions showed that the M coefficient and the coefficient of the f(R, M) attenuation term generally increased with period, which is consistent with regression results reported by others. The regression equations were reasonably accurate in predicting the response spectra of accelerograms recorded at Olympia and Seattle, Washington during the 1949 and 1965 Puget Sound earthquakes, but overestimated the spectra of the weaker motions recorded at Tacoma and Portland during the latter event. The median response spectra predicted by these equations for a Washington Coastal Ranges site were similar to the spectra computed by Heaton and Hartzell based on their simulations of ground motions from hypothetical giant earthquakes (M = 9.0 and 9.5) in the Pacific Northwest.

scholarly journals An ethic of care? Academic administration and pandemic policy

2021 ◽  
Vol 20 (1-2) ◽  
pp. 632-638
Author(s):  
Stephanie A Bryson
Keyword(s):  
Social Work ◽  
Political Theory ◽  
Pacific Northwest ◽  
Ethic Of Care ◽  
The Political ◽  
Academic Administration ◽  
The Public ◽  
Political Landscape ◽  
The Pacific ◽  
The Impact

This reflexive essay examines the adoption of an intentional ‘ethic of care’ by social work administrators in a large social work school located in the Pacific Northwest. An ethic of care foregrounds networks of human interdependence that collapse the public/private divide. Moreover, rooted in the political theory of recognition, a care ethic responds to crisis by attending to individuals’ uniqueness and ‘whole particularity.’ Foremost, it rejects indifference. Through the personal recollections of one academic administrator, the impact of rejecting indifference in spring term 2020 is described. The essay concludes by linking the rejection of indifference to the national political landscape.

Summary of Coastal Geologic Evidence for past Great Earthquakes at the Cascadia Subduction Zone

1995 ◽  
Vol 11 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Brian F. Atwater ◽  
Alan R. Nelson ◽  
John J. Clague ◽  
Gary A. Carver ◽  
David K. Yamaguchi ◽  
...  
Keyword(s):  
British Columbia ◽  
North America ◽  
Subduction Zone ◽  
Forest Soils ◽  
Pacific Coast ◽  
Cascadia Subduction Zone ◽  
Level Change ◽  
The Past ◽  
The Pacific ◽  
Juan De Fuca

Earthquakes in the past few thousand years have left signs of land-level change, tsunamis, and shaking along the Pacific coast at the Cascadia subduction zone. Sudden lowering of land accounts for many of the buried marsh and forest soils at estuaries between southern British Columbia and northern California. Sand layers on some of these soils imply that tsunamis were triggered by some of the events that lowered the land. Liquefaction features show that inland shaking accompanied sudden coastal subsidence at the Washington-Oregon border about 300 years ago. The combined evidence for subsidence, tsunamis, and shaking shows that earthquakes of magnitude 8 or larger have occurred on the boundary between the overriding North America plate and the downgoing Juan de Fuca and Gorda plates. Intervals between the earthquakes are poorly known because of uncertainties about the number and ages of the earthquakes. Current estimates for individual intervals at specific coastal sites range from a few centuries to about one thousand years.

scholarly journals What drives the evolution of hunter–gatherer subsistence technology? A reanalysis of the risk hypothesis with data from the Pacific Northwest

2011 ◽  
Vol 366 (1567) ◽  
pp. 1129-1138 ◽  
Author(s):  
Mark Collard ◽  
Briggs Buchanan ◽  
Jesse Morin ◽  
Andre Costopoulos
Keyword(s):  
Pacific Northwest ◽  
Northwest Coast ◽  
Contact Period ◽  
Hunter Gatherers ◽  
The Pacific ◽  
Wide Range ◽  
Relevant Variables ◽  
The Impact ◽  
The Relationship

Recent studies have suggested that the decisions that hunter–gatherers make about the diversity and complexity of their subsistence toolkits are strongly affected by risk of resource failure. However, the risk proxies and samples employed in these studies are potentially problematic. With this in mind, we retested the risk hypothesis with data from hunter–gatherer populations who lived in the northwest coast and plateau regions of the Pacific Northwest during the early contact period. We focused on these populations partly because the northwest coast and plateau differ in ways that can be expected to lead to differences in risk, and partly because of the availability of data for a wide range of risk-relevant variables. Our analyses suggest that the plateau was a more risky environment than the northwest coast. However, the predicted differences in the number and complexity of the populations' subsistence tools were not observed. The discrepancy between our results and those of previous tests of the risk hypothesis is not due to methodological differences. Rather, it seems to reflect an important but hitherto unappreciated feature of the relationship between risk and toolkit structure, namely that the impact of risk is dependent on the scale of the risk differences among populations.

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