Anqing earthquake; double-difference earthquake location algorithm; instrumental clock error; sPL; S-P arrival time difference

Accurate locations of aftershocks are helpful for understanding rupture process of the main shock. In order to suppress the impact of instrumental clock error, the arrival-time differences between S and P by the temporary seismic array installed after the 19 January 2011 Anqing earthquake were used to reconstruct the travel-time data of P and S and more accurate locations of the main shock and aftershocks were obtained by using master event and double-difference earthquake location algorithm; an algorithm was proposed to estimate the range of clock error; more reliable depth distribution of the aftershocks was also obtained via analysing sPL, a depth phase at near epicentral distance. The result shows that the Anqing earthquake occurred near Susong--Zongyang fault zone, and the aftershocks concentrated nearly horizontally in the depth range of about 5 km, spreading in the shape of a thin slab around 1.5 km long, 1.0 km wide and 0.3 km thick; the sequence tended to spread northeastward as time went on. The study suggests that earthquake location based on S--P arrival-time difference method can effectively eliminate the influence of clock error, providing reliable results for moderate, minor earthquakes and aftershocks.