Effects of Interface Rugosity on Elastic Wave Propagation

Interface rugosity affects wave propagation and it can produce poor imaging of the interface itself and of the underlying reflectors. We explore this effect on data generated with a full-wave elastic modeling code on 2D models. A variable rugosity top interface overlies a second plane interface. Seismic data is acquired on the surface with a standard split spread layout. We use the semblance computed along hyperbolic events on the common shot gather as “target detection” indicator. Interface rugosity is parameterized by the vertical amplitude and by the horizontal variability, defined respectively by the standard deviation with respect to the plane case, and by the maximum spatial frequency. Results show that, even for severe rugosity, the reflection from the deep interface is still detectable, whereas the reflection from the rough interface itself disappears when rugosity amplitude is higher than half the signal wavelength. This study can help in understanding wave propagation in volcanic media.