Application of P & SH-waves for rock anisotropy studies: Genting Highlands case study

Abstract

Seismic refraction surveys utilizing P & SH-waves were carried out over an abandoned quarry at Genting Highlands in order to study the anisotropy of the bedrock of that site. Shear (S) and compression (P) acoustic velocities of the subsurface refractor have shown significant variations in their spatial distribution. These variations in velocity values were compiled and then qualitatively correlated with surface fracture surveys conducted during the course of acquiring the field data. Seismic P & SH-wave velocity values obtained from in situ measurements have been used for calculating the anisotropy percentage and slowness factor. The petrophysical parameters computed are then contoured to identify the orientation of fracture zones along the refractor surface.

Behavior of seismic wave propagation with respect to fracture orientations in limestone, Perak, Malaysia

“…However, Fractures play important roles in influencing the velocity of propagating seismic wave. Seismic wave tends to propagate slower in the rock mass with high density of fractures and joints (Nassir Saeed et al 2000;Rafek 1985). Furthermore, fractures density is not the only factors delaying the arrival time of seismic signals.…”

“…Since seismic wave propagation is controlled by the elastic properties of rock mass, the variation of seismic velocities in different directions have help the investigation of elastic anisotropy. Most of the previous papers stated that the variation of seismic velocity in different directions is the result of elastic anisotropy in rock mass associated with the existence of discontinuities (Kleczek and Idziak 2008;Nassir Saeed et al 2000;Rafek 1985; Stan and Idziak 2005). Elastic seismic wave is known to travel faster in the direction of the strike of the fractures and slower when it is propagating in the perpendicular direction with the strike of the fracture sets (Kleczek and Idziak 2008;Nassir Saeed et al 2000;Rafek 1985; Stan and Idziak 2005).…”