Browsing by Author "Chan, Yu-Chang"

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Characterizing the Hsincheng active fault in northern Taiwan using airborne LiDAR data: Detailed geomorphic features and their structural implications
(2007-11-15)
Chan, Yu-Chang
;
Chen, Yue-Gau
;
Shih, Tian-Yuan
;
Huang, Chung
;
土木工程學系
We applied newly acquired high-resolution airborne LiDAR data to study a segment of the Hsincheng fault, a well-known active fault near a large industrial park in northern Taiwan. The Hsincheng fault has received much attention and study in the past; but high spatial resolution digital elevation models have not previously been applied to the study of the fault and its surrounding structures. We processed the acquired LiDAR data and produced I in digital elevation models (DEMs) to investigate the active fault adjacent to the densely populated and important infrastructure in Taiwan. Using the LiDAR DEMs, aerial photographs and topographic maps, we show highly detailed geomorphic characteristics around the study area of the Hsincheng fault. Three major characteristics of the study area are defined that include three very well preserved river terraces at varying levels, the fault/fold scarp of the Hsincheng fault, and meandering river systems. Using the LiDAR DEMs, we were able to detect with precision several fault/fold scarps and very gentle NE-trending folding of the river terraces. In general, the LiDAR DEMs have provided unprecedented clarity of landforms for one segment of the Hsincheng fault, which has helped the characterization of subtle but important geomorphic features. (c) 2007 Elsevier Ltd. All rights reserved.
Lidar DEM for characterizing the volcanic landforms of Tatun Volcanoes in Metropolitan Taipei
(2007)
Liu, Jin-King
;
Chan, Yu-Chang
;
Shih, Tian-Yuan
;
Hsieh, Yu-Chung
;
土木工程學系
Tatun Volcano Group is a cluster of dormant volcanoes surrounding Metropolitan Taipei. Rugged terrain, monotonic lithology and dense vegetation covers are adverse factors for mapping the geological structures. In this study, airborne Lidar survey was conducted to obtain a bare ground DEM with 2m grid and with an accuracy of decimeters. Shaded-relief images, pit-patterns and drainage networks are then derived from these DEMs for visual interpretation. 51 volcanoes are thus recognized. Two fissures running through the highest volcano in this area, namely Mount Seven-stars, are extending 2000m and 1000m, respectively. The largest width and depth of the opening of the ruptures is located in the west flank of the volcanic cone. The slope angle of the cast-wing of the volcanic cone is 36 degrees, whereas the angle of the west-wing is only 24.5 degrees. The opening of the west fissure is larger and its extension is longer than the east one. Thus, the west side can be subjected to an active extensional process of strain. The fissures could be resulted from the ongoing regional extension of the Tatun Volcanic area due to the plate subduction and collision of the Eurasian Plate and the Philippine Sea Plate.