Three‐dimensional dislocation model for great earthquakes of the Cascadia Subduction Zone

Flück, P.; Hyndman, R. D.; Wang, K.

doi:10.1029/97jb01642

Cited by 152 publications

(199 citation statements)

References 66 publications

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“…The Cascadia subduction zone in the Pacific Northwest forms the main boundary between the subducting Juan De Fuca plate and the overriding North America plate. The leading edge of subduction roughly follows the coastline about 100 km offshore, and the base of the locked zone is downdip at a depth around 10 km ( Figure 6) [Fluck et al, 1997;Wang et al, 2003]. Using the same parameters as in the previous sections, we calculate the fully relaxed stress change in response to 120 m of sea level rise and resolve normal stress onto a plane dipping 15°to the east and striking 5°west of north.…”

Section: Eustatic Ocean Loading At the Cascadia Subduction Systemmentioning

confidence: 99%

“…The magnitude of the stress perturbations also depends on the depth of observation within the plate relative to the plate thickness (z/h), with larger bending stresses near the surface and smaller stresses closer to the center of the plate (see Appendix A). We choose an observation depth of 10 km, which is a typical seismogenic depth on the transform faults considered here and is approximately the depth of the base of the elastic zone of the Cascadia subduction zone [Fluck et al, 1997].…”

Section: Plate Bending Stress From Ocean Loadingmentioning

confidence: 99%

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Ocean loading effects on stress at near shore plate boundary fault systems

Luttrell

Sandwell

2010

J. Geophys. Res.

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[1] Changes in eustatic sea level since the Last Glacial Maximum create a differential load across coastlines globally. The resulting plate bending in response to this load alters the state of stress within the lithosphere within a half flexural wavelength of the coast. We calculate the perturbation to the total stress tensor due to ocean loading in coastal regions. Our stress calculation is fully 3-D and makes use of a semianalytic model to efficiently calculate stresses within a thick elastic plate overlying a viscoelastic or fluid half-space. The 3-D stress perturbation is resolved into normal and shear stresses on plate boundary fault planes of known orientation so that Coulomb stress perturbations can be calculated. In the absence of complete paleoseismic indicators that span the time since the Last Glacial Maximum, we investigate the possibility that the seismic cycle of coastal plate boundary faults was affected by stress perturbations due to the change in sea level. Coulomb stress on onshore transform faults, such as the San Andreas and Alpine faults, is increased by up to 1-1.5 MPa, respectively, promoting failure primarily through a reduction in normal stress. These stress perturbations may perceptibly alter the seismic cycle of major plate boundary faults, but such effects are more likely to be observed on nearby secondary faults with a lower tectonic stress accumulation rate. In the specific instance of rapid sea level rise at the Black Sea, the seismic cycle of the nearby North Anatolian fault was likely significantly advanced.

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Section: Eustatic Ocean Loading At the Cascadia Subduction Systemmentioning

confidence: 99%

Section: Plate Bending Stress From Ocean Loadingmentioning

confidence: 99%

Ocean loading effects on stress at near shore plate boundary fault systems

Luttrell

Sandwell

2010

J. Geophys. Res.

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“…James et al, 2000). Dashed contour lines show the depth to the top of the subducting oceanic lithosphere (Fluck et al, 1997). Thick solid line shows the maximum extent of the Cordilleran Ice Sheet around 14 000 BP (Clague, 1983).…”

Section: Sample Collectionmentioning

confidence: 99%

Relative Sea-Level Change in the Northern Strait of Georgia, British Columbia*

James

Hutchinson

Barrie

et al. 2007

gpq

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Twenty-four new radiocarbon dates from isolation basin cores, excavations and natural exposures, and an archeological site, constrain relative sea-level change since the last glaciation in the northern Strait of Georgia, British Columbia. Relative sea level fell rapidly from about 150 m elevation to 45 m elevation from 11 750 to 11 000 BP (13 750 to 13 000 cal BP), then its rate of fall slowed. The initial rapid emergence began soon after the transition from proximal to distal glaciomarine sedimentation, when the glacial front retreated from the Strait of Georgia and the Earth’s surface was unloaded. A sea-level lowstand a few metres below present-day sea level may have occurred in the early Holocene, but sea level was near its present level by 2000 BP. Sea-level change in the northern Strait of Georgia lagged the mid Strait of Georgia, 80 km to the south, by a few hundred years during initial emergence. The lowstand in the northern strait was later and probably shallower than in the mid strait. Isostatic depression inferred from the sea-level observations can be fit with two decaying exponential terms with characteristic decay times of 500 and 2600 years. The faster decay time corresponds to a shallow mantle viscosity of about 1019 Pa s, consistent with previous glacio-isostatic modelling. The present-day crustal uplift rate from the residual isostatic effects of the Cordilleran Ice Sheet is about 0.25 mm/a. Crustal uplift is not expected to significantly ameliorate projected sea-level rise in the mid and northern Strait of Georgia because present-day vertical crustal movements are inferred to be small.Vingt-quatre nouvelles dates au 14C provenant de carottes sédimentaires de bassins isolés, d’excavations, de coupes naturellement exposées et archéologiques permettent de cerner les changements du niveau marin relatif depuis la dernière glaciation dans la partie nord du détroit de Géorgie, en Colombie-Britannique. Le niveau marin relatif a rapidement passé de 150 m à 45 m d’altitude entre 11 750 et 11 000 ans BP (13 750-13 000 cal. BP), le taux d’abaissement ayant ralenti par la suite. L’émersion initiale rapide correspond à la fin de la sédimentation glaciomarine distale qui accompagnait le retrait du front glaciaire. Un bas niveau de quelques mètres sous le niveau actuel a pu s’instaurer durant l’Holocène inférieur, jusqu’en 2000 ans BP. Au début, le soulèvement isostatique a accusé un retard de quelques siècle sur celui de la zone du détroit à 80 km plus au sud. Le bas niveau de la partie nord du détroit est survenu plus tard et fut moins prononcé. Les données indiquent un enfoncement isostatique de type exponentiel avec des constantes de désintégration de 500 et de 2600 ans 14C. Le taux le plus rapide correspond à une viscosité du manteau terrestre d’environ 1019 Pa s, ce qui concorde avec les résultats de la modélisation glacio-isostatique. Le taux de soulèvement glacio-isostatique actuel résultant de l’inlandsis de la Cordillère s’établit à environ 0,25 mm/a. Ce taux ne peut contrer les effets du rehaussemen...

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“…Thermal models of Flück et al (1997) and global analogs of shallow-dipping subduction zones were used to develop alternative rupture models. These models include ruptures that extend (1) through various depth ranges thought to be related to the elastic and transitional properties of the crust and (2) down to a depth of about 30 km similar to other large subduction earthquakes (Fig.…”

Section: Cascadia Subduction Zonementioning

confidence: 99%

Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2)

Field

Dawson

Felzer

et al. 2009

Bulletin of the Seismological Society of America

272

183

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The 2007 Working Group on California Earthquake Probabilities (WGCEP, 2007) presents the Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2). This model comprises a time-independent (Poisson-process) earthquake rate model, developed jointly with the National Seismic Hazard Mapping Program and a time-dependent earthquake-probability model, based on recent earthquake rates and stress-renewal statistics conditioned on the date of last event. The models were developed from updated statewide earthquake catalogs and fault deformation databases using a uniform methodology across all regions and implemented in the modular, extensible Open Seismic Hazard Analysis framework. The rate model satisfies integrating measures of deformation across the plate-boundary zone and is consistent with historical seismicity data. An overprediction of earthquake rates found at intermediate magnitudes (6:5 ≤ M ≤ 7:0) in previous models has been reduced to within the 95% confidence bounds of the historical earthquake catalog. A logic tree with 480 branches represents the epistemic uncertainties of the full time-dependent model. The mean UCERF 2 time-dependent probability of one or more M ≥ 6:7 earthquakes in the California region during the next 30 yr is 99.7%; this probability decreases to 46% for M ≥ 7:5 and to 4.5% for M ≥ 8:0. These probabilities do not include the Cascadia subduction zone, largely north of California, for which the estimated 30 yr, M ≥ 8:0 time-dependent probability is 10%. The M ≥ 6:7 probabilities on major strike-slip faults are consistent with the WGCEP (2003) study in the San Francisco Bay Area and the WGCEP (1995) study in southern California, except for significantly lower estimates along the San Jacinto and Elsinore faults, owing to provisions for larger multisegment ruptures. Important model limitations are discussed.

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Three‐dimensional dislocation model for great earthquakes of the Cascadia Subduction Zone

Cited by 152 publications

References 66 publications

Ocean loading effects on stress at near shore plate boundary fault systems

Ocean loading effects on stress at near shore plate boundary fault systems

Relative Sea-Level Change in the Northern Strait of Georgia, British Columbia*

Uniform California Earthquake Rupture Forecast, Version 2 (UCERF 2)

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