Resumen
By using profiling that focuses on seismic attenuation instead of reflectivity, we investigate geological structures in volcanic areas and fractured areas, where seismic reflections are difficult to observe. A previous study successfully visualized the hypocenter distribution of the earthquake swarm associated with the 2000 Miyakejima eruption from the seismic attenuation profile of a seismic line. However, any significant geologic features were not figured out on other nearby lines. In this paper, we re-evaluated our preprocessing of the seismic reflection data, which are the input for the seismic attenuation profiling method, with an eye toward improving frequency preservation. First, deconvolution was excluded from the preprocessing sequence, because it can potentially change the frequency content of seismic data. Second, a very small NMO stretching factor of 0.1, which does not allow reflections to stretch more than 10%, was adopted to minimize the frequency distortion by NMO correction. As a result, clear high-attenuation anomalies showed up on seismic attenuation profiles of the other nearby lines, which are consistent with typical geological features known in the study area: earthquake swarm and volcanic activity. This paper demonstrates that appropriate preprocessing was able to improve the accuracy of imaging geological structures by seismic attenuation profiling.