Abstract: Using the near-source Brune model, we determined apparent Stresses of 85 M_L≥2.0 earthquakes occurred in the eastern Capital Circle during January 2011 to May 2012 with seismic waveform data recorded by the Capital Circle Digital Telemetry Seismic Network. We analyzed temporal and spatial variation characteristics of dynamic parameters before the 2012 Tangshan M_S4.8 earthquake, and discussed the corresponding relationship with stress drop and source parameters. The results show that: (1) The apparent stresses have an obvious increase process before the 2012 Tangshan M_S4.8 earthquake; (2) High value area of apparent stress in the eastern Capital Circle is relevant to the earthquake source region before the 2012 Tangshan M_S4.8 earthquake.

Key words: Temporal and spatial variation of apparent stress, The 2012 Tangshan M_S4.8 earthquake, The Eastern Capital Circle