Abstract
The study investigated geomorphology of the Japan Trench located east of Japan, Pacific Ocean. A high-resolution GEBCO Gridded Bathymetric Dataset was used for modeling, mapping and visualization. The study aimed to compare and analyse variations in the geomorphic structures of the two parts of the trench and to visualize variations in the geological, geophysical and bathymetric settings. Technically, the cartographic work was performed using scripting based on the Generic Mapping Toolset (GMT). Modelled cross-sectioning orthogonal profiles transecting the trench in a perpendicular direction were automatically digitized and graphed in the two segments. The results of the bathymetric analysis shown that the southern part is shallower: with deeper values in absolute (139 samples between –7000 to –8000 m) and statistical records (the most frequent values are within –5500 to –5800 m) comparing to the northern segment (–5300 to –5500 m). The geomorphological analysis shows a more complicated relief in the northern part of the trench, which has a higher seismic activity. The southern part has a gentler slope on the Honshu island side. The geoid modeling along the trench ranges in 0–20 mGal. The highest values are recorded by the Honshu Island (>40 mGal). The rest of the area has rather moderate undulations (20–40 mGal). The free-air marine gravity of the Sea of Japan is <40 mGal. The results include 2D and 3D graphical models, thematic cartographic maps, spatial and statistical analysis of the Japan Trench geomorphology. Tested GMT functionality can be applied to future regional bathymetric modeling of the ocean trenches. All presented maps and graphs are made using GMT scripting toolset.
Highlights
Bathymetric mapping and geomorphic modelling of the deep-sea trenches is complicated to visualize and assess, since they are the deepest areas on the Earth
The objectives and goals of this paper are follows: 1) to visualize, map and compare several bathymetric grids (GEBCO, SRTM and ETOPO1 and ETOPO5) aimed to select the high-quality topographic data with detailed resolution; 2) using the data selected in the previous step, to map and analyse the geological, tectonic and geophysical characteristics controlling the geomorphology of the trench; 3) to perform automatic digitizing of the crosssection profiles aimed at the investigation of the geomorphic structure and shape of the Japan Trench in its two segments: the southern and the northern; 2) to compare the geomorphic structure of the Japan Trench obtained as a result of the data analysis and Generic Mapping Toolset (GMT) based profile modeling and to do a statistical analysis
In this study two segments of the Japan Trench have been studied with a comparative analysis of its northern and southern parts
Summary
Bathymetric mapping and geomorphic modelling of the deep-sea trenches is complicated to visualize and assess, since they are the deepest areas on the Earth. The application of the advanced mapping using computer assisted cartography and is of high importance. Mapping and modelling geomorphology of the deepsea trenches include the diverse methods for visualization of the bathymetric data. These can include the traditional GIS (e.g. ArcGIS, Map INFO, Erdas Imagine for raster grids visualization) and advanced scripting approach, such as a GMT. The GMT enables to perform both thematic mapping and graphical modelling (including statistical analysis) with a high quality output of maps, statistical graphs and models. Free-of-charge and open source GMT does not require expensive investments, comparing to the commercial GIS software
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