Investigating precursory changes in seismicity before the Bam Earthquake using Yazd seismic network data

Yazd telemetry seismic network of the Institute of Geophysics, University of Tehran is the closest local network to the Bam event of 2003/12/26 of 6.2 Mn. The network could detect larger number of earthquakes than other networks, thus allowing us to search for possible precursory changes of seismicity before the event. In this study we use the Yazd earthquake bulletin to detect possible seismicity activation before the events. Time evolution of integral measure of the intensity of earthquake flow, concentration of mainshocks, clustering of events and number of aftershocks are calculated for the Bam region. Our results show a significant increase of seismic activity about one year before the event happened. The results suggest that local network data might reduce the uncertainty in time of mid-term prediction algorithms to about one year