A. Ismail¹

¹National Research Institute of Astronomy and Geophysics (NRIAG)

Abstract:

A modern and sensitive seismic network (ASN) for monitoring the earthquakes beneath Nasser Lake has been operating in Aswan since June 1982. It is comprised of 23 field stations distributed south of Aswan High Dam. ASN records are clear and high quality digital waveform seismograms. In that region, seismic disturbances are also generated by the ongoing quarry blasts carried out mostly during the day time. Sometimes they are mistaken for the micro-earthquake activity of the area. Thus, the discrimination between quarry blast and local earthquake seismograms is important. In fact, multi-criteria investigations are now well known for identifying features which distinguish natural events (earthquakes) from explosions. This study presents a comparison between source properties of the quarry blasts and natural events (i.e., amplitude, periods and waveform). The P to S spectrum and logarithmic amplitude values of 15 quarry blasts and 15 micro-earthquakes of magnitude (ML) < 3 were compared with an attempt to examine the short-period discriminants on those events from Aswan area. Aswan seismic events are of near-source effects, which allows neglecting the propagation correction. The comparison between a quarry blast and an earthquake involves the source effects parameters (i.e., dynamic characteristics of waves, amplitudes, periods, and waveform).