23-25 September 2013
GEOMAR East shore
Europe/Berlin timezone
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Records of Mass Movement Events and Their Potential Triggers in the Active Fangliao Fault Zone Offshore Southwestern Taiwan

Presented by Dr. Ho-Han HSU on 23 Sep 2013 from 17:15 to 19:15
Type: Poster presentation
Session: Poster session
Track: Poster presentations

Content

In the past few years, large earthquakes and torrential rains triggered several large scale mass movement events offshore Southwestern Taiwan. They induced severe submarine hazards and caused series of submarine cable breakages. In this study, we use high-resolution bathymetry, chirp sonar, and seismic profile data together with core samples to investigate possible factors which may increase the vulnerability of generating submarine mass movements in the Fangliao Fault Zone offshore Southwestern Taiwan. Our study indicates that these mass movement events are not only related to earthquakes and floods, but that the geological and hydrological settings also play important roles in generating them. High-resolution bathymetric data and seismic reflection profiles show that the Fangliao and Hongtsai submarine canyons have different structural and sedimentary implications. The Fangliao Canyon is guided by a mud diapiric ridge which might be developed along a major north-south trending strike-slip fault zone in the incipient arc-continent collision system. This left-lateral strike-slip fault could have caused a major submarine landslide on the western side of the asymmetric Hengchun anticline, and shaped the Hongtsai canyon which flows into the Fangliao Canyon. The active tectonic environment and opposite vertical displacement rates in the west (subsidence) and east (uplift) sides of the Hengchun Fault make the study area highly vulnerable to large scale submarine mass movements. Chirp sonar profiles, in conjunction with core sample analyses are used to identify the sources, transport and deposition of the turbidites (or hyperpycnite), and to reconstruct the history of earthquake and flood events in the study area. They present mass movement deposits not only distributed in the offshore Southwestern Taiwan area, but parts of them could be transported to deep sea through submarine canyon systems in the form of turbidity currents. We reconstruct the possiable interactions between neotectonics and submarine canyon paleodrainages, and suggest that the geometries of the Fangliao and Hongtsai submarine canyons were affected by the activation of this Hongtsai submarine landslide. The tectonic setting and local structures include the active left lateral strike-slip fault, earthquakes, floods and submarine liquefaction structures are proposed to be the main factors which cause large scale submarine mass movement events offshore Southwestern Taiwan.

Place

Location: GEOMAR East shore
Address: Wischhofstr. 1-3 / D-24148 Kiel
Room: Lithothek

Primary authors

  • Dr. Ho-Han HSU Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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Co-authors

  • Prof. Char-Shine LIU Institute of Oceanography, National Taiwan University, Taipei, Taiwan
  • Prof. Benoît DEFFONTAINES Laboratoire de Géomatériaux et Géologie de l'Ingénieur, 5 Boulevard Descartes, Université de Marne-la-Vallée, F-77454 Marne-la Vallée Cedex 2, France
  • Prof. Chih-Chieh SU Institute of Oceanography, National Taiwan University, Taipei, Taiwan
  • Mr. Pei-Cheng HSIA Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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