Large-Scale Fluidization Features from Late Holocene Coseismic Paleoliquefaction in the Willamette River Forearc Valley, Central Cascadia Subduction Zone, Oregon, USA

Peterson, Curt D.; Kristensen, Kurt; Minor, Rick

doi:10.4236/ojer.2014.32009

Cited by 5 publications

(6 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, some previously reported estimates of inland shaking strength in the Cascadia margin, as based on seismic energy attenuation from an "assumed" narrow offshore "locked zone" [65], might be inaccurate. That is to say that the strength of shaking could be greater in the inland forearc valleys of the Cascadia convergence zone than previously thought, thus conforming to the large paleo-liquefaction/fluidization features found there [25].…”

Section: Selected Across-margin Profiles (Cross-sections) Of Integratsupporting

confidence: 62%

“…Coast Ranges in Washington and Oregon [25] the approximate widths of the uplifted ranges remain relatively similar (~100 km) along the length of the central margin. The band of ETS events only slightly widens in northern Washington and southern Oregon, relative to central Oregon, suggesting similar widths of inter-plate coupling seaward (west) of the forearc valleys (Figure 7(a)).…”

Section: Along-margin Variations In the Central Cascadia Primary Seismentioning

confidence: 99%

“…Slight thinning of the upper plate to the west (seaward) of the volcanic arc likely weakens inter-plate coupling along the forearc valleys, including the Puget Trough and Willamette Valley, both aligned north-south [31]. Further west (seaward) the shallowing dip angle (7˚ -10˚) of the subducting Juan de Fuca plate strengthens the inter-plate coupling, resulting in low-angle thrusting and/or underplating that has uplifted the Coast Range, generally striking north-south [23] [25]. Continued thinning and associated weakening of the upper plate to the west (seaward) towards the continental shelf, has permitted thrust faults and associated folds to extend to the upper-plate surface.…”

Section: Catastrophic Elastic Strain Release In the Cascadia Primary mentioning

confidence: 99%

“…Rainer, etc., are excluded from the plot. Many of the offshore events south of 47.5˚N are related to a divergent margin.tsunami inundation[63], and coseismic paleoliquefaction[25] [64]. The historic inter-plate seismic record does not serve as an indicator of past major mega-thrust ruptures in the Cascadia convergent zone, but it does help define the extent of the primary seismogenic structure.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Cascadia Convergent Zone: An Example of Primary Convergent Seismogenic Structure

Cruikshank¹,

Peterson²

2019

OJER

Self Cite

View full text Add to dashboard Cite

In this article, a case is made for very-large or primary seismogenic structures in convergent margins, based on anomalous large earthquake magnitudes (M w 8-9) relative to rupture lengths. Out of 56,293 earthquakes (magnitudes ≥ 5) cataloged worldwide, the 10 largest events in transform, divergent, and interior settings average magnitudes of 7.3-7.6. But in convergent margins, the average magnitude of the 10 largest events is 8.5, roughly 32 times more energy than the other neotectonic settings. The large anomalous magnitudes of energy release in convergent margins are attributed to the transfer of inter-plate stress to the upper-plate, where convergent elastic strain is accumulated during interseismic intervals. The large volumes of rock that accumulate the elastic strain in the upper-plates of convergent zones are defined here as primary seismogenic structures. Several datasets of 1) modern upper-plate convergent strain, 2) historical earthquakes, 3) modern upper-plate vertical displacements, and 4) recent inter-plate events of Episodic Tremor and Slip (ETS) are compared to establish the extent of the primary seismogenic structure in the Cascadia convergent zone. The across-margin extents of 1) significant convergent strain, 2) margin-parallel bands of vertical displacement, 3) historical seismicity and 4) ETS events, representing inter-plate coupling and shear stress transfer to strain accumulation in the upper-plate, are used to map the width of the primary seismogenic structure. The across-margin width of the primary seismogenic structure in the central Cascadia margin ranges from 300 km in the south-central margin to 450 km in the north-central margin, as mapped landward from the buried trench. A broad source region of coseismic energy release in the Cascadia primary seismogenic structure (300-450 km width) could yield stronger shaking in interior metropolitan centers from a future major rupture of the mega-thrust than has been modeled from a narrow "locked" zone located offshore under the outer continental shelf. Despite low dip angle and associated wide inter-plate coupling, the Cascadia margin likely serves as an example of inter-plate shear How to cite this paper: Cruikshank, K.M.

show abstract

Section: Selected Across-margin Profiles (Cross-sections) Of Integratsupporting

confidence: 62%

Section: Along-margin Variations In the Central Cascadia Primary Seismentioning

confidence: 99%

Section: Catastrophic Elastic Strain Release In the Cascadia Primary mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Cascadia Convergent Zone: An Example of Primary Convergent Seismogenic Structure

Cruikshank¹,

Peterson²

2019

OJER

Self Cite

View full text Add to dashboard Cite

show abstract

“…Estimated oblique convergence (030˚N -050˚N) of the central Cascadia margin at ~4 cm•yr −1 ( Figure 1) is associated with (1) episodic great subduction zone earthquakes (Mw 8.5 ± 0.5) with major-rupture recurrence intervals of 450 ± 250 years [7] [13] [14] [15] [16], (2) large-scale paleo-liquefaction features at 100 -170 km from the trench [17], and (3) nearfield paleo-tsunamis (10 ± 5 m) adjusted shoreline run-up [11]. It has been 316 years since the last Cascadia rupture at ~AD1700 [18].…”

Section: Central Cascadia Marginmentioning

confidence: 99%

Late Stage Interseismic Strain Interval, Cascadia Subduction Zone Margin, USA and Canada

Cruikshank¹,

Peterson²

2017

OJER

Self Cite

View full text Add to dashboard Cite

Modern horizontal strain (2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) measured along 56 new and 108 previously published GPS station baselines are used to establish the length (800 km) and width (300 -400 km) of the central Cascadia convergent margin seismogenic structure. Across-margin (west-east) annual rates of shortening range from 10 −9 a −1 at the eastern (landward) limit of the central Cascadia seismogenic structure to 10 −7 a −1 along the western onshore portion of the interplate zone. Relatively high shortening strain rates (10 −8 a −1 to 10 −7 a −1) are also measured in western transects from the northern (Explorer plate) and southern (Gorda plate) segments of the convergent margin, demonstrating that the full length of the margin (1300 km length) is currently capable of sustaining and/or initiating a major great earthquake. Vertical GPS velocities are averaged over the last decade at 321 stations to map patterns of uplift (0 -5 mm yr −1 ) and subsidence (0 -9 mm yr −1 ) relative to the study area mean. Along-margin belts of relative uplift and subsidence, respectively, are approximately associated with Coast Ranges and the Cascade volcanic arc. However, the vertical velocity data are locally heterogeneous, demonstrating patchy "anomalies" within the larger along-margin belts. A large coastal subsidence anomaly occurs in southwest Washington where the modern shortterm trend is reversed from the long-term (~200 yr) tidal marsh record of coastal uplift since the last co-seismic subsidence event (AD1700). The modern vertical displacements represent a late stage of the current inter-seismic interval. If the horizontal strain is considered largely or fully elastic, extrapolating the modern strain rates over the last 100 years show the accumulated strains would be similar in magnitude to the observed co-seismic strains resulting from the Tōhoku, Japan, Mw 9.0 earthquake in 2011. We believe that the central Cascadia seismogenic structure has accumulated sufficient elastic strain energy, during the last 300 years, to yield a Mw 9.0 earthquake from a rupture of at least one-half (400 km) of its length.

show abstract

Compilation and forecasting of paleoliquefaction evidence for the strength of ground motions in the U.S. Pacific Northwest

Rasanen

Marafi²,

Maurer

2021

Engineering Geology

View full text Add to dashboard Cite

Large-Scale Fluidization Features from Late Holocene Coseismic Paleoliquefaction in the Willamette River Forearc Valley, Central Cascadia Subduction Zone, Oregon, USA

Cited by 5 publications

References 26 publications

Cascadia Convergent Zone: An Example of Primary Convergent Seismogenic Structure

Cascadia Convergent Zone: An Example of Primary Convergent Seismogenic Structure

Late Stage Interseismic Strain Interval, Cascadia Subduction Zone Margin, USA and Canada

Compilation and forecasting of paleoliquefaction evidence for the strength of ground motions in the U.S. Pacific Northwest

Contact Info

Product

Resources

About