Abstract: In this paper, by using the waveform data of medium and small earthquakes in Shandong province, we calculated the earthquake energy, seismic moment and apparent stress of 206 M_L≥2.0 earthquakes from January 2001 to July 2011 based on Brune model. The scaling relations of source parameters turns out that apparent stress increase with the seismic moment, except the earthquakes with M_L≤2.8 from September 2008 to March 2011 during which time the apparent stress was low. The temporal and spatial variation of apparent stress shows that the stress level in Shandong province obviously increased from 2004 to 2007, and the high value concentrated in Anqu—Changyi, Juxian—Tancheng, Liaocheng—Lankao,and jiaodong peninsula, the stress remained low after 2009 and began to rise from March 2011, which deserves continous concern.

Key words: Temporal and spatial variations of apparent stress, Dynamic source parameters, Shandong province