Submarine stability evaluation of the Philippine Sea of the Western Pacific based on microgeomorphologic features

In addition to underwater resource development, submarine construction and engineering have become great concerns to marine geoscientists. Both of them require accurate sea-bottom stability evaluation. However, mainly due to the limitation of offshore technology, it is difficult for the time being to acquire high-precision data for accurate and comprehensive evaluation of the stability. In order to solve this problem, a method for stability evaluation of submarine engineering is proposed in this paper based on microgeomorphologic features. Based on the existing research, this paper selected a region in the south-central Philippines Sea of the Western Pacific as the target area, and a Digital Elevation Model (DEM) using ArcGIS is established to extract macro and micro geomorphological factors. Combined with seismic data, bottom sediments and distribution pattern of geo-hazards in the study area, the fuzzy mathematical evaluation method was adopted to evaluate the submarine stability, and an evaluation map was compiled. The results show that by analysis of the stability for 3220 evaluation units in the region, the seabed can be divided into 5 grades according to its stability, including stable, basic stable, relatively stable, relatively unstable and unstable. The stable areas are mainly located in the central and northern part where the sea bottom is flat, while the unstable areas occur in the large-scale geomorphic units such as the Kyushu-Palau Ridge, seamounts and intermontane basins. It is revealed that the stability of the seabed of the study area is closely related to the change in topography and landform. The practice proves that the submarine stability evaluation method based on micro-geomorphic features proposed in this paper is useful and efficient, and may well serve the stability evaluation required in similar regions.