Embedded Files
1. Frequency-dependent tidal triggering of low-frequency earthquakes on the San Andreas Fault
Using a 15-year catalog of low-frequency earthquakes (LFEs) along the deep San Andreas Fault, we examine how solid earth tides influence LFEs activity at different frequencies. Our analysis reveals spatially coherent but highly variable LFE responses along the fault. Through rate-and-state friction modeling, we demonstrate that background effective normal stress controls tidal modulation amplitude, while fault frictional properties and the nucleation time of LFEs govern frequency-dependent responses. These spatial variations highlight heterogeneous lower-crustal geologic structure and complex physical faulting processes below the rupture zone of eventual great earthquakes.
Xue L., Bürgmann R., Zhao Z., Beeler N.M., Heimission E.R., Shelly D. R. (2025), Probing lower-crustal fault properties with frequency-dependent tidal tremor triggering, EPSL. (link)
2. Tidal triggering of ordinary earthquakes in Southern California
We investigate how the ordinary earthquakes (OEs) in Southern California respond to tidal stresses. Using a 40-year Southern California Seismic Network catalog and a 10-year Quake Template Matching catalog, we find that the correlation between earthquakes and tides varies spatially. Regions with significant tidal modulation of OEs are primarily associated with geothermal locations. Additionally, in certain areas, earthquakes with deeper depth or specific types (strike and thrust) are more likely correlated with tides. These results suggest that the effective background normal stress and tidal loading amplitude are key factors controlling the response of seismicity to tides. This implies that tidal triggering of OEs could be used as a probe to measure the in-situ background stress.
Lu W., Xue L., Yue H., Zhuang J.C., Zhao L., Exploring Tidal Modulation of Seismicity in Southern California, submitted to JGR, under review.
3. The responses of low-frequency earthquakes and ordinary earthquakes to tidal and hydrogeological loadings
By analyzing seismicity from the central SAF, we demonstrate that OEs have a stronger response to annual hydrological loading, while LFEs are more responsive to daily tidal forces. This divergence unravels pore fluid diffusion during the non-instantaneous earthquake nucleation and different nucleation times of LFEs and OEs. The modulations of LFEs and OEs at different periods provide a good constraint on depth-dependent fault properties, revealing that fluid distribution and loading conditions fundamentally control slow-to-fast slip behaviors.
Zhao Z., Xue L., Bürgmann R., Heimisson E.R., Lu W., Yue H., Tidal and Hydrological Modulations Reveal Pore Fluid Diffusion during Earthquake Nucleation, submitted, under review.
Page updated
Google Sites
Report abuse