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Improved Rapid Source and Shaking Characterization Using Large Seismic Array Observations

Description: 

Rapid and accurate determination of finite source models and seismic intensity maps for damaging earthquakes are paramount for effective earthquake disaster mitigation and subsequent secondary hazard estimation. However, obtaining such estimates in the initial hours after a large event remains challenging, particularly for earthquakes with large source extents in regions with limited local seismic observations. In this study, we present improvements over our earlier strategy based on back-projection array technologies. Our approach involves estimating the source energy radiation utilizing multiple regional seismic array contributions, obtaining stable estimates of the fault geometry and subevent relative amplitudes. By combining Ground Motion Models and the estimated subevent distribution, we calculate Peak Ground Velocities (PGVs) directly by applying PGV-based site corrections using the USGS global Vs30 database. Alternatively, we can project the resulting subevents (high frequency radiators) onto fault geometries for use in estimating shaking with USGS ShakeMap. We evaluate our algorithm using representative earthquakes that occurred in recent years, including the 2024 Mw 7.5 Japan earthquakes.

Though we observe variations in our results obtained from different array geometries, the inferred fault planes approximate the finally determined rupture area well and the seismic intensity maps we produce exhibit a high degree of similarity with ShakeMaps constrained by strong motion and macroseismic data, where available. A noteworthy benefit of this approach is it does not rely on real-time local strong-motion observations. Ultimately, we intend to automate these algorithms, enabling the issuance of reliable seismic intensity maps shortly after damaging earthquakes. Such efforts could benefit post-earthquake decision-making and tsunami hazard evaluation.

Reference：Chen, W., Wang, D., Si, H., & Zhang, C. (2022). Rapid Estimation of Seismic Intensities Using a New Algorithm That Incorporates Array Technologies and Ground‐Motion Prediction Equations (GMPEs). BSSA, 112 (3), 1647-1661.

Session: Creating Actionable Earthquake Information Products - I

Type: Oral

Date: 5/1/2024

Presentation Time: 08:45 AM (local time)

Presenting Author: Dun

Student Presenter: No

Invited Presentation: 

Authors