Seismic structure of the Bohai Bay Basin, northern China: Implications for basin evolution

As part of an extensive seismic research program, 33 portable broadband seismic stations were deployed along a line crossing the Bohai Bay Basin, northern China. Three teleseismic events were selected to constrain the seismic structure along a ∼280 km profile across the western edge of the basin. We determined the basin structure that described the observed shear horizontal (SH) wave field. The synthetic SH wave was calculated using a finite difference (FD) method with its computational domain localized in the basin area and input motions at the base of the model extrapolated from the displacement recorded at a nearby hard-rock station. Synthetic seismographs calculated for the models match the observations well in both waveform and travel time. Numerical tests indicate that the structural features of the preferred models are well resolved. The analysis of relations between structures and stratigraphic units along the cross sections allows multiple deformational events in the basin to be inferred. In conjunction with a profile across the southern edge that has been presented previously by Zhao et al. [14] [L. Zhao, T.Y. Zheng, W.W. Xu, Modeling the Jiyang depression, Northern China, using a wave field extrapolation FD method and waveform inversion, Bull. Seismol. Soc. Am. 94 (2004) 988–1001], the results reveal basin-wide extension with local inversion features in the Bohai Bay basin.