Present-day kinematics of Neogene extensional
structures in the foreland of southwestern Taiwan
from GPS observations during 2002-2012

a Ruey-Juin Rau, a Chia-Hsun Yang, a Sz-Man Ko,
b Kuo-En Ching and c Chien-Liang Chena Department of Earth Sciences, National Cheng Kung University, Taiwanb Department of Geomatics, National Cheng Kung University, Taiwan
c Central Geological Survey, MOEA, Taiwan

12Tectonic Setting of Taiwan

3Geology of Taiwan and Mesozoic basement depth map

林殿順4

Tectonics and Seismicity of Taiwan

51600-2012
Significant
earthquakes inTaiwan

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2001-20127

GPS strain rate in Taiwan

1993-1999

Hsu et al., 20098

Profiles across Taiwan

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SW Taiwan Horizontal Velocity Field
Strike-Slip Fault:
A Kukeng fault
B B-Structure
C Meishan fault
D Yichu fault
E Hsinhua fault
Fold-and-Thrust System:
F Changhua-Chiuchiungkeng fault
G Liuchia-Muchiliao fault
H Tachienshan-Chukou fault
I Longchuan fault
J Tamaopu-Shuangtung fault
K Chishan fault
L Liukuei fault
M Chaochou fault
Others:N Houchiali fault
O Tsochen fault

337 campaign GPS stations
117 continuous GPS stations
Geologic map is refined from
CPC geologic map (Chow et al.,1988 and Yang et al., 1991),
CGS geologic map (Chen et al.,2000) andYang et al., 200720

SW Taiwan Focal Mechanism 1991-2012
01: 1736 M 6.1
Dep. 5 km
02: 1792 M 6.7
Dep. 5 km
03: 1839 M 6.5
Dep. 15 km
04: 1862 M 6.6
Dep. 15 km
05: 1904 M 6.1
Dep. 6.0 km
06: 1906 M 7.1
Dep. 15.0 km
07: 1941 M 7.1
Dep. 15.7 km
08: 1946 M .61
Dep. 5.0 km
09: 1964 M 6.3
Dep. 18.5 km
10: 1998 M 6.2
Dep. 12.0 km
11: 1999 M 7.3
Dep. 12.0 km
12: 1999 M 6.4
Dep. 21.0 km
13: 2010 M 6.4
Dep. 22.6 km

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Principal Strain Rate

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Principal Strain Rate and Damaging Earthquakes

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Shear Strain Rate

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Horizontal Velocity Field of Tsochen fault

25Principal Strain Rate of Tsochen fault

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Shear Strain Rate of Tsochen fault27

3D Block Modeling Approach (Horizontal Data)
Concept of modeling interseismic velocity field (DEFNODE: McCaffrey, 2002)

Ching et al. [2011](Slip Rate Deficit)
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Distribution of Blocks

Velocity between
Observation and Calculation

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Fault Slip Rate andBlock Strain

Principal Strain Rate

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Behavior of Changhua fault and Chelungpu fault* Fault-Parallel and Fault-Perpendicular velocities include campaign
and continuous GPS data.
Vertical velocity includes continuous GPS and precise levelingdata.

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Behavior of Chiuchiungkeng fault and Tachienshan
fault* Fault-Parallel and Fault-Perpendicular velocities include campaign
and continuous GPS data.
Vertical velocity includes continuous GPS and precise leveling
data.

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Behavior of Muchiliao-Liuchia fault and Chukou fault* Fault-Parallel and Fault-Perpendicular velocities include campaign
and continuous GPS data.
Vertical velocity includes continuous GPS and precise leveling
data.

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Behavior of B-Structure, Meishan fault, and Yichu
fault* Fault-Parallel and Fault-Perpendicular velocities include campaign
and continuous GPS data.
Vertical velocity includes continuous GPS and precise leveling
data.

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Behavior of B-Structure, Meishan fault, and Yichu
fault* Fault-Parallel and Fault-Perpendicular velocities include campaign
and continuous GPS data.
Vertical velocity includes continuous GPS and precise leveling
data.

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Model of Present-Day Crustal Deformation in SW Taiwan

36Summary
1. A series of pre-orogenic Neogene extensional
structures in western Taiwan have inverted andremain active
2. Frontal thrusts and the pre-existing extensional
faults are the two most important seismogenic
structures in western Taiwan
3. SW Taiwan has experienced nine large
earthquakes over the last 220 years, and is due
for another!
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