Geophysical Modelling of the Middle America Trench using GMT
Annals of Valahia University of Targoviste. Geographical Series, 19(2), pp. 73-94. DOI: 10.2478/avutgs-2019-0008
22 Pages Posted: 14 Apr 2020
Date Written: December 31, 2019
The study is focused on the geomorphological analysis of the Guatemala Trench, East Pacific Ocean. Research goal is to find geometric variations in western and eastern flanks of the trench and correlation of the submarine geomorphology with geologic settings and seismicity through numerical and graphical modelling. Methods include GMT based analysis of the bathymetry, geomorphic shape and surface trends in topography and gravity grids. Dataset contains raster grids on bathymetry, gravity, geoid and geological layers. Technical workflow is following: 1) Bathymetric mapping by modules ('grdcut', 'grdimage'); 2) Datasets visualizing and analysis, 3) Topographic and gravimetric surface modelling by ASCII data; 4) Cartographic mapping ('psbasemap', 'psxy', 'grdcontour') 4) 3D-mesh modelling; 5) Automatically digitized orthogonal cross-stacked profiles (‘grdtrack’); 6) Visualizing curvature trends (‘trend1d’); 7) statistical histograms. Results reveal unevenness in the structure of the submarine landforms. Modelling cross-section profiles highlighted depth variation at different parts of the transects and seafloor segments. Geomorphic structure has straight shape form of the slopes with steep oceanward forearc. Its geometry has steep and strait shape which correlates with seismicity. Depth samples vary: -3000 to -6200 m, seafloor is 3-5 km wide. Trench has symmetric accurate 'V- shaped' geometric form for the segment of -30 to -30 km. Oceanward side slope increases towards continental shelf, left flank stabilizes in depths at -50 km from the trench axis, deepens at -50 to 0 m, decreases at -3,200 to -5,800. Oceanward flank gradient varies: slope steepness of 35,63° at 0-20 km, 42,17° at 20-40 km, 44° at 40-60km. Left flank has 43,24° at 0-24 km, 28,33° at 24-40 km, 14° at 40-60 km, 1,13° at 60-200 km. Marine vertical gravity correlates with tectonic slab contours (20-30 mGal on the trench slopes). The study demonstrated effective GMT-based framework with a multi-disciplinary scope that combined cartographic methods of modelling deep-sea trench profiles with geological, bathymetric and geophysical analysis. Technical application of the advanced cartographic solutions and high quality mapping by GMT demonstrated its functionality for data analysis and effectiveness of the geoinformation processing. Proposed techniques and workflow methodology provided framework for geological mapping and can be applied in further similar research.
Keywords: GMT, data analysis, bash script, oceanic trench, geomorphology, Pacific Ocean, geology
JEL Classification: C00, C02, C15, C18, C31, C60, C63, C65, C83, C88, C90, Y10, Y92, Q24, Q25, Q35, Q42, Q43, Q51
Suggested Citation: Suggested Citation