Impact of down-dip rupture limit and high stress drop subevents on coseismic land-level change during Cascadia megathrust earthquakes
Geophysical Research Letters
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Abstract
Seismic hazard associated with Cascadia megathrust earthquakes is strongly dependent on the landward rupture extent and heterogeneous fault properties. We use 3-D numerical simulations and a seismic velocity model for Cascadia to estimate coseismic deformation due to ~M9 earthquake scenarios. Our earthquake source model is based on observations of the 2010 M8.8 Maule and 2011 M9.0 Tohoku earthquakes, which exhibited distinct strong-motion-generating subevents in the deeper portions of the fault. We compare our estimates for land-level change to paleoseismic estimates for coseismic coastal subsidence during the A.D. 1700 Cascadia earthquake. Results show that megathrust rupture extending to the 1 cm/yr locking contour provides a good match to geologic data, and along-strike variations in coastal subsidence can be produced by including strong-motion-generating subevents in the down-dip regions of the megathrust. This work demonstrates the potential to improve seismic hazard estimates for Cascadia earthquakes by comparing physics-based earthquake simulations with geologic observations.
Suggested Citation
Wirth, E.A., and Frankel, A.D., 2019, Impact of down-dip rupture limit and high stress drop subevents on coseismic land-level change during Cascadia megathrust earthquakes: Geophysical Research Letters, v. 109, no. 6, p. 2187-2197, https://doi.org/10.1785/0120190043.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Impact of down-dip rupture limit and high stress drop subevents on coseismic land-level change during Cascadia megathrust earthquakes |
| Series title | Geophysical Research Letters |
| DOI | 10.1785/0120190043 |
| Volume | 109 |
| Issue | 6 |
| Publication Date | October 29, 2019 |
| Year Published | 2019 |
| Language | English |
| Publisher | American Geophysical Union |
| Contributing office(s) | Earthquake Science Center |
| Description | 11 p. |
| First page | 2187 |
| Last page | 2197 |
| Country | United States |
| Other Geospatial | Cascadian Fault |