NTUGeo
- TCDP: S.R. Song and T.F. Yang
To understand the earthquake rupture process, energy balance among the tectonic stresses, dynamic friction, radiated energy, and heat dissipation of Chi-Chi earthquake, a proposal for the Taiwan Chelungpu-fault Drilling Project (TCDP) was put forth jointly by National Taiwan University (NTU) NationalCentralUniversity(NCU). Principal investigators (PIs) from USA, Japan and Germany will study drilled core samples from the fault zone to understand the physical and chemical mechanisms involved in faulting during earthquakes.The maximum drilling depth was 2 km, and a continuous core sampling is conducted for the bottom 1.5 km. The target interval where the large slip was plotted to be located was reached at the depth of about 1.2 km. The results derived from the borehole studies will help clarify the following working hypotheses: (1) the fault zone was lubricated while generating large slip and slip velocity; (2) weak faults, i.e. slip under conditions of low resolved shear stress; (3) physical properties, chemistry, and state of the fault zone changed with time throughout the earthquake cycle (interseismic and coseismic).
- Paleo-seismic (Trenching) studies: W.S. Chen
By grant supports from the National Science Council (NSC) and Central Geological Survey (CGS), trench excavation started after the 1999 Chi-chi earthquake.The first phase witnessed tens sites along the Chelungpu fault and tentatively gave a recurrence interval of 350 to 400 years for a characteristic 1999 earthquake.The same technique is applied elsewhere to obtain relevant information with regard to other active faults in Taiwan.The faults investigated include the Hsincheng F., Houchiali F., Coastal Range F., and Chiuchiungkeng F.This work will continue to obtain information urgently needed for earthquake hazard mitigation.
- Remote Sensing: J.C. Hu
From a seismic hazard viewpoint, the monitoring of deformation built up during the interseismic period is a major concern for seismic hazard assessment in Taiwan. In the first phase, we aim at establishing a continuous GPS network with a microseismic array in eastern Taiwan across the Chihshang Fault and the LongitudinalValley. In addition, the new PSInSAR techinique (Permanent Scatters InSAR) will be used in Taiwan to overcome the disadvantage of the bad coherence of the InSAR studies due to dense vegetation and mountainous terrain in Taiwan. Other new PIV (Particle Imaging Velocity) techniques can be applied for subpixel correlation of SPOT images and aerial photography to detect surface changes. Finding traces of active faults is often crucial for better assessment of seismic hazards. The new technique using Airborne LiDAR can provide high-precision DEM data and facilitates the detection of minor change in elevation and subtle geomorphic features. It is critical for evaluating and determining active structures of interest. In addition, together with other satellite images such as IKONOS, Quickbird and SOPT imagery, LiDAR-derived DEM can extend its application to monitoring environmental changes.
- Early warning study for large earthquakes: Y.M. Wu
To attain early seismic warning, finding the relationship between P wave signals and earthquake magnitude to shorten the earthquake reporting time is urgently needed since Taiwan is so highly populated. This study is aimed to mitigate potential damage utilizing a warning signal prior to the arrival of the quake. In addition, for the purposes of emergency response, the relationship between strong peak motions and seismic damage assessment is largely established and is helpful to the government in organizing a post-earthquake rescue system.
