역시간 구조보정의 역전파 알고리듬을 이용한 굴절 주시 토모그래피

Abstract

We developed a new refraction tomography algorithm based on the backpropagation technique of reverse time migration. In our algorithm, the objective function is built into the residuals between the respective phases of first arrivals in the field data and in the forward modeled data. The phases of first arrivals in model responses can be obtained by taking the natural logarithm of strongly damped monochromatic wavefields, whereas those of field data are generated by multiplying first arrival traveltimes picked in field data by the same angular frequency that is used for the computing phases of model responses. In order to avoid the explicit computation of Frechet derivatives, we exploit the symmetry of Green's wave equation function, and implicitly calculate the steepest descent with the reverse time migration technique.