Seismic station sites response as a discriminant tool between earthquakes and quarry blasts in Aswan region, Upper Egypt

Abstract

This study estimates the spectral ratio of the horizontal to the vertical components (H/V SR) on seismic (earthquakes and quarry blasts) data recorded by ten permanent broadband seismic stations in Aswan region. These seismic stations were operated by the Aswan Seismological Research Center and the National Egyptian Seismic Network, National Research Institute of Astronomy and Geophysics. The H/V SR analysis included shallow micro-earthquakes with depth less than 5 km and magnitude ranging from 1.6 to 2.9 and quarry blasts with magnitude range of 1.9–2.8. The values of H/V SR of the studied seismic stations showed significant amplification peaks with different dominant frequencies at each station. These differences in results could probably be because of the different soil and geological conditions of local station sites and structures heterogeneities of the investigated region. In the frequency range of 0.1 Hz–1 Hz, H/V SR for earthquakes showed lower amplification level than for quarry blasts. In the frequency range from 1.0 to 10 Hz, the H/V spectral ratio curve for quarry blasts and earthquakes showed similar amplification response and resonance frequencies. In the frequency band of 10–20 Hz, the H/V spectral ratio for quarry blasts showed higher amplification response than that for earthquakes. The dominant frequencies show similar behavior for both seismic data sets at each station at frequencies from 10 to 20 Hz. Our results of the H/V spectral ratio of a single station site may be used to differentiate between quarry blasts and local micro-earthquakes in Aswan region.