Spatial and Temporal Changes in Shallow Sedimentary Layers in Upstream Gaoping Submarine Canyon Area (II)

As a major pathway of the sediment transportation, the submarine canyons sculpture the seafloor then deposit sediments at the deep ocean. The submarine canyons could be divided into two categories: erosive or deposition based on geological environment or fluid flow down to the canyon. The erosive canyons often “attack” the levee which may result in submarine landslides or mass transportations due to slope failure. Once slope failure occurs at geological weakness area such as gas hydrate dissociation zone, giant mass slumping will be triggered. These kinds of mass transportations will further develop turbidity current or hyperpycnal flow, which could damage the submarine fiber optic cables or pipes. The giant mass transportation even triggers devastated tsunami. Therefore, we propose a three year and apply multiple near seafloor high resolution geophysical observation methods such as swath bathymetry, spark type MCS, sub-bottom profiler as well as side scan sonar in mid-to-up stream Gaoping submarine canyon area. The strategy is repeating geophysical surveys before and after devastated typhoon and flooding events during three year project. We have conducted two high resolution geophysical surveys along and across the upstream Kaoping Canyon area since end of August, 2017 during first year project. The preliminary results show that an erosional environment may be controlled by active mud diapirism, an opposite depositional environment is in the north of the canyon. These data are still under processing and analyses. In addition to understand the temporal variation and relationship with tectonic processes not only on mass transportation deposits but also on dynamics of turbidity and hyperpycnal flow, multi-year observation strategy must be applied.