台灣地震地質研究-台灣西南部活斷層研究─台灣西南部活斷層的大地構造分析
Date Issued
2005
Date
2005
Author(s)
DOI
932119M002012
Abstract
Southwestern Taiwan comprises part of the collision orogen and its neighboring
foreland area. The foreland area is characterized by an array of NEE to E-trending,
south-dipping normal faults buried beneath the Yun-Chia plain. The collision orogen
is marked by imbricated NNE-trending, east-dipping thrusts and overthrusts that are
either exposed on the surface or buried in the subsurface.
Normal faults of the foreland formed mainly in the late Miocene as a result of
crustal extension in the China continental margin that has ceased to be active since the
Pliocene. Presently these normal faults are undergoing NW-directed compression
and some have been reactivated as reverse or strike-slip faults. The thrusts of the
collision orogen are the product of the E-W compression, which continues pushing
the orogenic pile to deform internally. The deformation front of the orogen, where the
gravitational force induced by the orogenic pile is the smallest and the devitoric stress
greatest, is the area most prone to thrusting and, hence, is the area of highest potential
for active faulting.
Based on available geodetic data, the area near the deformation front of the
collision orogen has the greatest strain rate in southwestern Taiwan. Numerous late
Quaternary faults, including some causing disasters in the historical records, are
located in that area. Recent instrumental records also show that earthquakes of
compressional mechanisms are distributed near the deformation front. All these
phenomena seem to indicate that faults near the deformation front are the most active
in southwestern Taiwan.
Subjects
Southwestern Taiwan
Active Fault
Earthquake
structural geology
Tectonics
Publisher
臺北市：國立臺灣大學地質科學系暨研究所
Type
report
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