Abstract: In this paper, the tectonic ambient shear stress and apparent stress varying characteristics of the small earthquake sequences in “Huoshan seismic window” was studied in detailed by using the digital earthquake data in Anhui Province and its adjacent region. The results indicate that the value of tectonic ambient shear stress and apparent stress not only reflects strong or weak stress background in earthquake source region but also the information of stress background around earthquake generating area in special tectonic position, namely the small earthquake in seismic window of “seismic activity point” farther from the future strong earthquake epicenter. The difference of the stress state is distinct before and after moderately strong earthquake in East China region.

Key words: Huoshan Seismic window, Tectonic ambient shear stress, Apparent stress, Moderately strong earthquake in East China region