WITHDRAWN Kinematic Slip Model of the Mw7.0 December 5, 2024 Offshore Cape Mendocino Earthquake
Description:
WITHDRAWN The M7.0 December 5, 2024 Offshore Cape Mendocino earthquake is the largest earthquake in the triple junction area since the Mw7.2 April 25, 1992 Cape Mendocino earthquake. Focal mechanisms of the mainshock and largest aftershocks are consistent with right-lateral strike slip on the ~east-trending Mendocino fracture zone (MFZ). The December 2024 rupture closely follows the December 2021 Petrolia Mw6.1 and Mw6.0 earthquake doublet, which also initiated on the MFZ, and the Mw6.4 December, 2022 Ferndale intraslab earthquake (Yoon and Shelly, 2024). In order to clarify the location and amount of slip in the December 2024 earthquake, we assemble three-component broadband seismograms from 91 regional stations within 300 km of the main shock epicenter, combined with 89 horizontal coseismic offsets derived from Global Navigation Satellite System (GNSS) time series and a Sentinel-1 ascending interferogram. These data are interpreted with a model of slip distributed on two vertical fault planes with slightly different strikes, representative of the eastern MFZ and spanning the ~70 km length of aftershocks. Assuming right-lateral strike slip, we find that slip occurs in two distinct pulses. The first occurs within ~4s of the origin time and is isolated near the USGS-determined hypocenter at the western end of the rupture zone, and the second occurs ~10s after the origin time near the initial locus of slip, followed by unilateral rupture propagation towards the east. This model is consistent with two distinct direct P arrivals observed in three-component record sections. We shall investigate the precise nature of the temporal gap in initial slip as well as any possible relationship between the spatial distribution of net coseismic slip and the slip of the first (Mw6.1) of the 2021 Petrolia earthquakes.
Session: Advances in Reliable Earthquake Source Parameter Estimation [Poster]
Type: Poster
Date: 4/16/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Fred
Student Presenter: No
Invited Presentation:
Poster Number: 33
Authors
Fred Pollitz Presenting Author Corresponding Author fpollitz@usgs.gov U.S. Geological Survey |
Katherine Guns kguns@usgs.gov U.S. Geological Survey |
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WITHDRAWN Kinematic Slip Model of the Mw7.0 December 5, 2024 Offshore Cape Mendocino Earthquake
Category
Advances in Reliable Earthquake Source Parameter Estimation