Increasing High-frequency Seismic Radiation before Large Earthquakes

Yehuda Ben-Zion, Fengjiang Ju, Longtan Wang, & Haoran Meng

Submitted August 30, 2026, SCEC Contribution #15169, 2026 SCEC Annual Meeting Poster #TBD

Detecting precursory information before large earthquakes is a fundamental goal of earthquake science with considerable societal implications. We present observational results on increasing high-frequency seismic radiation during several years before M ≥ 7 mainshocks in California, Japan, Turkey, and Taiwan. Specifically, we analyze evolving (1) minimum root-mean-square velocity amplitude of the seismic wavefield at several high-frequency bands, (2) corresponding high-frequency power spectral density, (3) rates of detected P- and S-wave arrivals, and (4) dominant polarization azimuth of the high-frequency wavefield. The pre-earthquake evolutionary trends are reversed following the mainshocks. The signals are recorded at sensitive near-fault stations and are not seen at all stations. The reproducibility of these observations across multiple earthquake sequences, independent monitoring networks, and diverse tectonic environments point to a common physical process in the evolving near-fault crust. The observations are consistent with extended space-time failure/weakening processes on the scale of the ruptures before the earthquakes. This contrasts with and is more informative than nucleation of instabilities that involve only the near-hypocenter regions. The results open new possibilities for developing forecasting algorithms that incorporate signals of extended preparation processes and underscore the importance of near-fault observations.

Citation
Ben-Zion, Y., Ju, F., Wang, L., & Meng, H. (2026, 08). Increasing High-frequency Seismic Radiation before Large Earthquakes. Poster Presentation at 2026 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology