Taiwan Seismic Microzonation Map of the Design Basis Earthquake: Construction of A Geometric Model of the Chukou and Lunghou Faults

Taiwan Seismic Microzonation Map of the Design Basis Earthquake: Construction of A Geometric Model of the Chukou and Lunghou Faults

The National Center for Research on Earthquake Engineering (NCREE) constructed a comprehensive model of active faults for nuclear sites when executing the project “Reevaluation of Probabilistic Seismic Hazard of Nuclear Facilities in Taiwan Using SSHAC Level 3 Methodology.” However, the models for other faults are not detailed enough for application in PSHA hazard maps and require continued research. The scope of this project is the construction of an applicable fault geometric model for PSHA hazard map. At the current stage, we have constructed a geometric model of active faults of central Taiwan. We here briefly describe how the fault geometric model was created, and we evaluate its uncertainty based on integrated data, including surface geological surveys, boreholes, balanced cross-sections, and seismic reflection data. The lengths of the Chukou and Lunghou fault are 25 km and 50 km, respectively. The dipping angles of both faults are 25/40/50 degrees, and their down-dip depth contacts the 7 degrees décollement. We propose a rupture model of three scenarios: (1) individual rupture of the Chukou or Lunghou fault；(2) linked rupture, and (3) Entire rupture with the southern segment of the Tachienshan fault.