Spatiotemporal Detection of Seismic Quiescence prior to the 2010 ML 6.4 Jiashian, Taiwan Earthquake

On 4 March 2010, the ML 6.4 Jiashian earthquake struck southern Taiwan and caused some damage due to the strong ground shaking. Since the epicenter is located in a relatively low background seismicity area, we want to investigate seismicity rate changes associated with the Jiashian mainshock by applying the region-time-length (RTL) algorithm. The temporal RTL function shows that, for the epicenter area, a seismic quiescence stage appeared during 2007-2009, and then the seismic activation stage started just few months before the mainshock and continued for almost 2 years. On the other hand, the spatial distribution also indicates that the mainshock occurred on the edge of seismic quiescence area. In addition, quiescence patches correspond to the region with Coulomb stress drop during the same period. Therefore, our study suggests that the epicenter area of the 2010 Jiashian earthquake experienced a long period of seismic quiescence followed by a short period of seismic activation before the mainshock.