Assessing Margin‐Wide Rupture Behaviors Along the Cascadia Megathrust With 3‐D Dynamic Rupture Simulations

Self Cite

Section: Resultssupporting

confidence: 88%

The Effect of Fore‐Arc Deformation on Shallow Earthquake Rupture Behavior in the Cascadia Subduction Zone

Aslam

Thomas

Melgar

2021

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“…(Priest et al, 2010) produces similar tsunami amplitudes to those from our model shown in (b), both in the Pacific (c and d) and along the coastline (e). Also, a dynamic M w = 9.2 rupture (Ramos et al, 2021) derived from the Gaussian locking model (f) and our choice of locking model (g) result in similar tsunami amplitudes both in the Pacific (h and i) and along the coastline (j). The dots next to coastline show locations of virtual gauges.…”

Section: Discussionmentioning

confidence: 82%

Relative Tsunami Hazard From Segments of Cascadia Subduction Zone For M_w 7.5–9.2 Earthquakes

Salaree

Huang

Ramos

et al. 2021

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Coupling between the subducting Juan de Fuca plate and the overriding North America at the shallow-dipping Cascadia subduction zone (Crosson & Owens, 1987) is expected to cause future large earthquakes and tsunamis. Previous studies (Atwater, 1987;Goldfinger et al., 2017;Satake et al., 2003) show that the ∼1,100 km plate boundary extending from British Columbia to northern California has generated large tsunamis in the past. The tsunami from the most recent great Cascadia earthquake or sequence of events, with an inferred total magnitude of 9 (

“…Similarly, simulations based on state-of-the-art techniques are used as added sources of information (Frankel et al, 2018;Ramos et al, 2021;Ramos & Huang, 2019;Wirth et al, 2018).…”

Section: Figurementioning

confidence: 99%

Deep Coseismic Slip in the Cascadia Megathrust Can Be Consistent With Coastal Subsidence

Melgar

Sahakian

Thomas

2022

Self Cite

The Cascadia Subduction Zone (Figure 1, CSZ) is a 1,200 km plate boundary that extends from the Mendocino Triple Junction in Northern California to the tectonically complex region surrounding the Explorer Plate offshore of Northern Vancouver Island (Braunmiller & Nábělek, 2002;Savard et al., 2020). It accommodates roughly 4 cm of annual convergence between the Juan de Fuca and North American plates (DeMets et al., 2010). It is well established that the CSZ hosts magnitude 9+ earthquakes and is the dominant source of seismic hazard in the region (Petersen et al., 2020).The most recent great earthquake occurred in 1700, this is supported by a variety of geologic observations summarized in Walton & Staisch, et al. (2021). Across the margin there are instances of buried marsh soils and sand over mud contacts interpreted to represent sudden coseismic subsidence and deposition soon after caused by a tsunami. Microfossil analyses at these coastal marshes allow quantification of the subsidence (Figure 2). Similarly, there is evidence of deep-sea turbidite in cores, these are inferred to be deposited simultaneously at locations across the plate boundary and are thought to be seismically-induced. Historical documents in Japan reveal that a tsunami occurred in Honshu at sites as far as ∼800 km apart without an accompanying earthquake. From these documents Atwater et al. (2005) and Satake et al. ( 2003) deduced the amplitudes of the tsunami there and hydrodynamic modeling found that an earthquake in the M8.7-M9.2 range rupturing most of the CSZ could simultaneously explain the North-American and Japanese observations. Despite this knowledge, quantifying seismic hazards has been challenging because recurrence intervals are long, and no large events have occurred in the instrumental record. Geodetic locking models (Li et al., 2018;Schmalzle et al., 2014) can provide estimates of fault moment rates but do not resolve the offshore region clearly. Paleoseismic inferences of magnitudes and recurrences of events (Goldfinger et al., 2012(Goldfinger et al., , 2017Nelson et al., 2021) can be used as well. This information can be combined with suitable ground motion models (GMMs; e.g., Abrahamson et al., 2016), which estimate the severity of ground motions for an earthquake as a function of magnitude, source dimensions, distance, and local geology to make inferences about likely shaking and its probability of occurring.