Seafloor receiver function analysis for hybrid dataset composed of both refraction survey and earthquake records

Abstract

In this study, we present two types of simulation models that consist of a sediment layer, a crust layer, and a sloped interface that are marked as seismic velocity discontinuities. Seismometers are aligned on the seafloor. One model has only surface seismic sources and the other has buried seismic sources that are equivalent to natural earthquakes. For every shot or earthquake, we obtain either refracted or converted waves from the velocity interfaces. We estimate a receiver function for each shot or earthquake for our sub-seafloor structural analysis. After these processing, the receiver function analysis is justified to estimate velocity interface and the applicable method of refraction wave analysis. For the first models, we confirmed that our receiver function could estimate the depth and shape of the velocity interface precisely. The refracted waves propagate beneath the velocity interfaces and generate both refracted compressional and converted shear waves that are used to estimate receiver functions at each location of seismometers. Our result indicates that the receiver function analysis can be applied to refraction seismic survey data using artificial seismic sources located near the surface above the target structure. Finally, we include seismic records from the buried sources in our receiver function analysis, and combine results from refraction survey and conventional earthquake data. Although data processing such as seismic migration becomes necessary, our results demonstrate that receiver function analysis can be applied not only for conventional earthquake records but also for artificial seismic surveys. Our analysis to synthetic data demonstrates the effectiveness of the method and the necessity of fair wave decomposition techniques to separate both compressional and shear waves from observed wavefield.