Development of a detection method for short-term slow slip events using GNSS data and its application to the Nankai subduction zone

Abstract Using global navigation satellite system (GNSS) data to detect millimeter-order signals of short-term slow slip events (S-SSEs) and estimate their source parameters, especially duration, is challenging because low signal-to-noise ratio. Although the duration S-SSEs in Nankai subduction zone has been estimated using tiltmeters, its regional variation never quantitatively studied. We developed an S-SSE detection method both fault model with errors based on methods by previous studies applied it a 23-year period GNSS zone. extracted calculating correlation coefficients between time series synthetic template representing evolution computing average weighted predicted signals. enhanced for estimation stacking displacements calculated from model. By applying method, we detected 284 1997 2020 Tokai Kyushu discussed characteristics. The results include some newly S-SSEs, including accompanying very low-frequency earthquakes repeating offshore Kyushu. Our study provides first geodetic evidence synchronization other seismic phenomena cumulative error carefully. also rate dividing duration. This clarified that western Shikoku was approximately twice as eastern These differences were statistically significant at 95% confidence interval. Multiple factors can influence characteristics speculate subducting plate interface geometry one dominant factors. Graphical