Correction to: The efficiency of horizontal to vertical spectral ratio technique for buried monuments delineation (case study, Saqqara (Zoser) pyramid, Egypt)

Abstract

Site investigation studies provide the basic soil and engineering properties, which usually determined using many investigations as standard penetration test, cone penetration test, and multichannel analysis of surface wave (MASW), to identify and evaluate a potential hazard. The horizontal to vertical spectral ratio (HVSR) analysis method is a tool based on the spectral analyses of recorded ambient noise; it is widely used to estimate site effect parameters (fundamental frequency and the associated soil amplification), and many surveys using this technique to study the site effect have provided convincing results. Saqqara pyramid lies to the southwest of Cairo near the epicenter of Cairo earthquake that happened on 12 October 1992. The pyramid is severely damaged by the earthquake with epicenter at about 14 km away; as a result, numerous efforts are exerted to restore the pyramid and to prevent it from total collapse. The current work is motivated by such efforts with focus on the potentiality of using the spectral ratio method (HVSR) to define subsurface monuments. The microtremor measurements were performed at 15 sites distributed in front of the southern side of the Zoser pyramid region in order to calculate the HVSR. Array shape and dimensions is chosen based on the prior information about the location and extension of the tunnel underneath. The tunnel extended about 20 m underneath the area adjacent to the southern gate of the pyramid. The amplification spectra have been evaluated for the soil column at each site location, and the fundamental frequency obtained and peak amplitudes are contoured showing some low value trends at the area adjacent to the southern gate. This may lead to the possibilities of the HVSR method to explore the subsurface monuments. However, this statement is still in the early stage and further theoretical investigation is required.