Detailed surface co-seismic displacement of the 1999 Chi-Chi earthquake in western Taiwan and implication of fault geometry in the shallow subsurface

The northern segment of the Chelungpu Fault shows an unusually large co-seismic displacement from the event of the Mw 7.6 Chi-Chi earthquake in western Taiwan. Part of the northern segment near the Fengyuan City provides an excellent opportunity for characterizing active thrust-related structures due to a dense geodetic-benchmark network. We reproduced co-seismic deformation patterns of a small segment of this Chelungpu Fault using 924 geodetic benchmarks. According to the estimated displacement vectors, we identified secondary deformations, such as local rigid-block rotation and significant shortening within the hanging wall. The data set also allows us to determine accurately a 3D model of the thrust fault geometry in the shallow subsurface by assuming simple relations between the fault slip, and the horizontal and vertical displacements at the surface. The predicted thrust geometry is in good agreement with borehole data derived from two drilling sites close to the study area. The successful prediction supports our assumptions of rigid displacement and control of displacement in the hanging wall by the fault geometry being useful first approximations.

[1]  张哉根,et al.  Leu-M , 1991 .

[2]  H. Kao,et al.  Exactly Where Does the 1999 Chi-Chi Earthquake in Taiwan Nucleate?-Hypocenter Relocation Using the Master Station Method , 2000 .

[3]  Jyr-Ching Hu,et al.  Geometry and structure of northern surface ruptures of the 1999 Mw=7.6 Chi-Chi Taiwan earthquake: influence from inherited fold belt structures , 2002 .

[4]  J. Angelier,et al.  Le séisme du 21 septembre 1999 : influence de l'héritage structural et implication du socle au front de la chaı̂ne de Taiwan , 2001 .

[5]  C. S. Ho.  A synthesis of the geologic evolution of Taiwan , 1986 .

[6]  H. Kao,et al.  Stress Tensor Inversion for the Chi-Chi Earthquake Sequence and its Implications on Regional Collision , 2004 .

[7]  K. Okamoto,et al.  Fossil fluid reservoir beneath a duplex fault structure within the Central Range of Taiwan: implications for fluid leakage and lubrication during earthquake rupturing process , 2005 .

[8]  J. Suppe,et al.  Structural geology of a classic thrust belt earthquake : the 1999 Chi-Chi earthquake Taiwan ( M w Z 7 . 6 ) , 2005 .

[9]  S. Stein,et al.  A model for the motion of the Philippine Sea Plate consistent with NUVEL‐1 and geological data , 1993 .

[10]  Rémi Michel,et al.  Horizontal coseismic deformation of the 1999 Chi-Chi earthquake measured from SPOT satellite images: Implications for the seismic cycle along the western foothills of central Taiwan , 2003 .

[11]  Toru Ouchi,et al.  Co-seismic displacements, folding and shortening structures along the Chelungpu surface rupture zone occurred during the 1999 Chi-Chi (Taiwan) earthquake , 2001 .

[12]  J. Angelier.  Inversion of earthquake focal mechanisms to obtain the seismotectonic stress IV—a new method free of choice among nodal planes , 2002 .

[13]  James P. Evans,et al.  Fault Structure Control on Fault Slip and Ground Motion during the 1999 Rupture of the Chelungpu Fault, Taiwan , 2003 .

[14]  C. Lee,et al.  Representative styles of deformation along the Chelungpu fault from the 1999 Chi-Chi (Taiwan) earthquake: Geomorphic characteristics and responses of man-made structures , 2004 .

[15]  H. Philip,et al.  Structural analysis and interpretation of the surface deformations of the El Asnam Earthquake of October 10, 1980 , 1983 .

[16]  Chung-Pai Chang,et al.  Strain and stress field in Taiwan oblique convergent system: constraints from GPS observation and tectonic data , 2003 .

[17]  Yuan-Hsi Lee,et al.  Area Balancing Method as a Useful Tool to Estimate the Depth of the Chi-Chi Earthquake Rupture at the Fengyuan Well , 2006 .

[18]  H. Kao,et al.  The chi-Chi earthquake sequence: active, out-of-sequence thrust faulting in taiwan , 2000, Science.

[19]  Characteristics of surface ruptures associated with the Chi-Chi earthquake of September 21, 1999 , 2004 .

[20]  Jia‐Jyun Dong,et al.  The influence of surface ruptures on building damage in the 1999 Chi-Chi earthquake: a case study in Fengyuan City , 2004 .

[21]  Yu-Chang Chan,et al.  Structure of the 1999 Chi-Chi earthquake rupture and interaction of thrust faults in the active fold belt of western Taiwan , 2007 .

[22]  Yuan-Hsi Lee,et al.  Slip vectors of the surface rupture of the 1999 Chi-Chi earthquake, western Taiwan , 2003 .

[23]  C. Wang,et al.  Structural mapping of the 1999 Chi-Chi earthquake fault, Taiwan by seismic reflection methods , 2002 .

[24]  Y. Hsu,et al.  Preseismic deformation and coseismic displacements associated With the 1999 Chi-Chi, Taiwan, Earthquake , 2004 .

[25]  J. Angelier,et al.  Reconstruction of fault slip of the September 21st, 1999, Taiwan earthquake in the asphalted surface of a car park, and co-seismic slip partitioning , 2003 .

[26]  Yue‐Gau Chen,et al.  Thrust-related river terrace development in relation to the 1999 Chi-Chi earthquake rupture, Western Foothills, central Taiwan , 2003 .

[27]  C. Wang,et al.  Initial Science Report of Shallow Drilling Penetrating into the Chelungpu Fault Zone, Taiwan , 2002 .

[28]  Yi-Ben Tsai,et al.  Le séisme de Chichi(1999) et sa place dans l'orogène de TaiwanThe Chichi earthquake, 1999, and its role in the Taiwan orogen , 2001 .

[29]  Yi-Ben Tsai,et al.  Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project , 2006, Nature.

[30]  H. Sawa,et al.  Geomorphological identification of pre-existing active Chelungpu Fault in central Taiwan, especially its relation to the location of the surface rupture by the 1999 Chichi earthquake , 2004 .

[31]  Shui-Beih Yu,et al.  Velocity field of GPS stations in the Taiwan area , 1997 .

[32]  J. Angelier,et al.  Active deformation of Taiwan from GPS measurements and numerical simulations , 2001 .

[33]  J. Angelier,et al.  Kinematics of convergence, deformation and stress distribution in the Taiwan collision area: 2-D finite-element numerical modelling , 1996 .