Assessing the potential of in-gallery seismic shots in exploring buried structures of ‘Ain Zubaidah using acoustic wavefield modeling

Abstract EN

A numerical modeling approach, approximating the solution of the 2-D heterogeneous, acoustic wave equation with second-order accuracy in both time and space, is utilized to unravel the hidden potential of the in-gallery seismic shooting technique as an effective tool in accurately locating buried shafts (Karez), as well as gallery routes, of ‘Ain Zubaidah, Makkah Al Mukarramah area, Kingdom of Saudi Arabia.

Numerical models indicated that gallery routes could vividly be delineated as conspicuous, high amplitude reflections and that should equally be true for deeper galleries because of the high S / N ratio of seismic wave energy generated by in-gallery seismic shots.

This should provide an accurate and cost-effective tool for exploring relatively wide areas.

Although these findings should be applicable to similar geological problems, even in subsurface structures characterized by velocity inversions, a word of caution, however, is that they are applicable only to air-filled or slightly water-filled galleries.

This situation should change when ground water level increases during rainy seasons, where the velocity of loose saturated sediments should at a minimum be around that of water (1500 m / sec), masking their presence.

This is also true for shafts inundated in ground water.

Accordingly, the season when to carry field surveys is important in gaining similar success in other areas.