Application of Spherical Interpolation Locator to Relocate Far-Field Clustered Seismicity

Earthquake location is of great significance for earthquake early warning (EEW) and earthquake research. Accurately determining the location of earthquake clusters provides valuable insights into understanding fault zone distributions. The traditional methods require more than four seismic stations, but this can be alleviated by the primary events. Therefore, we proposed a unified spherical interpolation (SI) location framework, which can realize earthquake cluster relocation according to different observation conditions (the number of available stations and primary events). We have validated the efficacy of the SI relative locator through its successful application to the 2019 Ridgecrest earthquake and 2023 Jishishan earthquake within a sparse network featuring only two seismic stations and a known set of primary events. Our results provide good initial results for horizontal locations and are well-suited for subsequent insertions of ray-tracing techniques based on finer models to determine depths more accurately.