Impact of down-dip rupture limit and high stress drop subevents on coseismic land-level change during Cascadia megathrust earthquakes
October 29, 2019
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.
Citation Information
Publication Year | 2019 |
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Title | Impact of down-dip rupture limit and high stress drop subevents on coseismic land-level change during Cascadia megathrust earthquakes |
DOI | 10.1785/0120190043 |
Authors | Erin A. Wirth, Arthur Frankel |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Geophysical Research Letters |
Index ID | 70208138 |
Record Source | USGS Publications Warehouse |
USGS Organization | Earthquake Science Center |