Digital Elevation Model Offshore Taiwan and Its Tectonic Implications

A new 500-m gridded digital bathymetric data set has been produced by compiling available shipboard bathymetric data supplemented by glo bal bathymetric data sets in the area between 18N and 27N, and from 117E to 125E. Combined with topographic data from GTOP030, a global land data set in 30 arc-second gr id spacing, this new digital elevation model (DEM) reveals the regional as well as local morphology of Taiwan and its offshore area. Spatial resolution of 1 km is achieved in the area off eastern and southern Taiwan where swath bathymetric data are available. In other areas where ship tracks are sparse, a spatial resolution of 4 arc-minute is retained. This DEM provides the best topographic information at present on a regional scale, which helps to reveal many of the morphotectonic fea tures related to the active tectonic processes of subduction and arc-conti nent collision in this region. Using 2-D shaded topographic maps and 3-D physiographic diagrams generated from the DEM, the major morphologic features in each te ctonic province of the region are presented. The Taiwan Strait is characterized by low relief sea floor with two NE-SW trending depressions and a shallow bank in the center of the strait. Submarine canyons mark the continental slope. In the area off southern Taiwan, N-S trending ridges and tr oughs are the major morphological features, however, several NE-SW trending lin eaments have been identified in the Luzon forearc region. Off eastern Tai wan, submarine canyons and topographic features related to sedimentary processes along the eastern flank of the Luzon Arc are revealed in detail.