GMT Based Comparative Analysis and Geomorphological Mapping of the Kermadec and Tonga Trenches, Southwest Pacific Ocean

Current study is focused on the GMT based modelling of the two hadal trenches located in southwest Pacific Ocean, eastwards from Australia: Tonga and Kermadec. Due to its inaccessible location, the seafloor of the deep-sea trench can only be visualized using remote sensing tools and advanced algorithms of data analysis. The importance of the developing and technical improving of the innovative methods in cartographic data processing is indisputable. Automatization in data analysis has been significantly increased over the past years. However, using programming and scripting in cartography still remains lower comparing to the use of the traditional GIS. Therefore, developing GMT-based methods for the geomorphological data processing is crucial for better understanding the landforms of the seafloor. Methodology includes application of the GMT scripting toolset for the automated digitizing of the profiles crossing the trenches in perpendicular direction. A sequence of the GMT codes enabled to visualize raster and vector data, perform geomorphological modelling, descriptive statistical data analysis and quantitative comparison of the two trenches. Using GMT, the bathymetric sample data of the Kermadec and Tonga trenches were modeled, analyzed and compared. The results show deeper bathymetry and more seafloor roughness for the Tonga. Comparing to Kermadec, Tonga Trench has steeper gradient of the profiles. The seafloor geomorphology is strongly affected by a variety of factors that shape actual form of both trenches. The experimental methodology is fully based on the GMT scripting with presented and explained codes.