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Source and Along-path Seismic Parameters of S-waves From Earthquakes in the Central-northern Gulf of California, Mexico

Description: 

I used 114 S-wave recordings from 27 earthquakes with epicenters in the central-northern Gulf of California (GoC), Mexico, and applied a one-step least-squares inversion approach to separate source and path effects from the amplitude Fourier acceleration spectra of the vertical components of ground motion. I then parameterized the nonparametric source and along-path spectra using Brune’s (1970, 1971) ω² source model and an exponential function containing the S-wave Quality factor (Q_S), respectively. I found evidence that the stress drop values, on average, follow self-similar scaling behavior, although the number of recordings in my database is limited. Furthermore, earthquakes with lower stress drops tend to occur near the Canal de Ballenas Rift and Basin, an extensional zone within the central-northern GoC, whereas earthquakes with relatively higher stress drops tend to occur along the Salsipuedes Transform Fault, a zone characterized by right-lateral strike-slip events. Overall, I found a median stress drop of 15.3 MPa. Finally, I estimated an average Q_S = (98.3 ± 2.9)f^{(0.64 +- 0.01)} when assuming a geometrical spreading of r^-1.0 for r ≤ 80 km and r^-0.5 for r > 80 km. I expect my results to contribute to the ongoing debate on scaling behavior and lateral variability of the stress drop. Furthermore, these findings enhance our understanding of the physics governing earthquakes and ground motion in the central-northern GoC.

Session: Advances in Reliable Earthquake Source Parameter Estimation [Poster]

Type: Poster

Date: 4/16/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Juan

Student Presenter: Yes

Invited Presentation: 

Poster Number: 24

Authors