Geophysical characteristics of active submarine sand waves off the coast of Dongfang, Hainan Island

Abstract

Abstract A large number of sand waves are developed on the seafloor off the coast of Dongfang, Hainan Island. This paper analyzes the geophysical characteristics of active submarine sand waves synthetically by using multi-beam echo-sounding(MBES), side-scan sonar(SSS), sub-bottom profiler (SBP), and single-channel seismic(SCS) data, and discusses the distribution characteristics, migration mechanism, activity, and morphologic evolution characteristics of sand waves. The results show and confirm that there are significant spatial differences in the distribution and scale of submarine sand waves, large and medium-sized sand waves mainly develop on the sand ridge, small sand waves mainly develop on both sides of the sand ridge, and near-symmetrical sand waves develop in the pit and trough area. Submarine sand waves were not developed in the southwest of the study area. Constrained by tidal current and Coriolis force, the migration direction of the sand wave on the west side of the submarine sand ridge is mainly north (slightly east), while that on the east side is mainly south (slightly west). Due to the topography, the migration of near-symmetric sand waves may stop or the migration direction has changed. The signatures of strong active submarine sand waves mainly include: (a) Asymmetric "ridge tip trough gentle" shape; (b) Superimposed small sand waves and sand ripples development on submarine sand waves; (c)Sub-bottom profile has transparent layer; (d)Reflection on the steep slope is blank; (e) Internal oblique progradation configuration. The analysis shows that the activity of the sand wave is closely related to its morphology, including three evolution stages low activity, high activity, and motionless.