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Using Local and Regional Travel Time Data From the ISC to Estimate Lithospheric Velocity Structure

Description: 

While a great deal of seismic data is openly available, there are still some regions not well-covered by stations with open waveform data. In many of these cases, however, arrival data from stations is contributed to the International Seismological Centre (ISC). In the absence of waveform data, how effectively can we utilize available ISC data to determine velocity structure? We have developed a method of using simplified ray paths to model regional phases, and use this method to model Pn, Pb, Pg, Sn, Sb, and Sg phases from crustal events in East Asia. The travel times are then used to tomographically invert for P-wave and S-wave velocities in the crust and upper mantle, as well as corresponding source terms, which can accommodate errors in origin time and depth, and site terms, which can accomodate local station conditions (e.g., Vs30). We start with the simplest parameterization (layer over a half-space) and then introduce additional complexity (e.g., variable Moho thickness, additional crustal layers) to gauge its effect on our model. Preliminary results show some success in retrieving the expected variations in crust and mantle velocities from the seismo-tectonic structure, but a higher-order parameterization might be needed to capture the overall complexity of the region. We can test the predictive nature of the models with the observed travel times from ground-truth (GT) events not used in the development of the model. If proven to be effective, we can readily apply the method to other regions where waveform data may be limited.

Session: Earth’s Structure from the Crust to the Core - I

Type: Oral

Date: 5/1/2024

Presentation Time: 09:00 AM (local time)

Presenting Author: Michael

Student Presenter: No

Invited Presentation: 

Authors