12:00 PM - 1:00 PM
Some large interplate earthquakes are found to be preceded by seismicity acceleration around the hypocenter. Whether it could be explained by cascade triggering or background slow slip is still controversial. Although some large earthquakes, e.g. the 2014 Mw 8.2 Iquique earthquake, are preceded by slow slip confirmed by geodetic observations, the possible precursory signals before most large earthquakes are unclear. In this talk, I will present our recent efforts to apply template matching methods to detect precursory microseismicity and repeating earthquakes, which are possibly driven by slow slip. The results show that abundant newly detected earthquakes down to M 1 appear to accelerate over a large area ~3-4 days before the 2015 Mw 7.8 Gorkha earthquake. This is more consistent with the scenario where small events are driven by background slow aseismic slip. Another example shows that both the repeater-inferred aseismic slip and the seismicity appear to accelerate within the last ~150 days before and in a large scale surrounding the 2015 Mw 8.4 Illapel mainshock. Our results highlight the possible role of slow-slip signals in unloading the impending rupture area.