An integrated long‐wavelength statics method applied to seismic processing of Tibetan permafrost

Abstract

Permafrost in high‐altitude regions complicates near‐surface modelling and exacerbates static effects during seismic processing and interpretation, especially in the form of long‐wavelength issues in cases where it extends laterally beyond the length of the seismic wavelength. The long‐wavelength component of static corrections (statics) for permafrost when solved using a single conventional method is prone to seismic imaging artefacts due to limited field layouts and unmet preconditions. The nonlinearity between the velocities and the thickness from low‐velocity near surface to high‐velocity bedrocks ulteriorly complicates near‐surface modelling for long‐wavelength statics by first‐arrival inversion. Combining the advantages of as much long‐wavelength characteristics as possible associated with the permafrost and rugged topography, we estimate an integrated long‐wavelength statics method including tomographic inversion and refraction residual statics. The integrated method can approximate linearized near‐surface modelling through multi‐step processing. An example from the Qiangtang Basin (central Qinghai–Tibet Plateau) suggests that the integrated method is capable of gradual refining complex near‐surface modelling and long‐wavelength statics and eliminates upward‐stretching abnormalities caused by Tibetan permafrost.