Terr. Atmos. Ocean. Sci., Vol. 19, No. 6, 683-696, December 2008
|
doi: 10.3319/TAO.2008.19.6.683(PT)
|
Coseismic Surface
GPS
Displacement and Ground Shaking Associated with the 2006 Pingtung Earthquake
Doublet, Offshore Southern Taiwan
Horng-Yue Chen, Jian-Cheng
Lee, Long-Chen Kuo, Shui-Beih
Yu and Chi-Ching Liu
Institute of
Earth Sciences
, Academia Sinica,
P.O. Box 1-55 Nankang,
Taipei
,
Taiwan
Abstract
Two
successive large earthquakes (ML= 6.96 and 6.99) occurred
in southern Taiwan offshore of the Hengchun town, Pingtung county, with the
two main shocks separated by an interval of only 8 minutes. Based on a dense
network of continuously recording GPS stations (CORS) in Taiwan and adopting
two different post-processing methods, we estimate the coseismic
displacements and characterize their ground motions. Daily solution
algorithm is used to determine the total coseismic displacements of the dual
main shocks from 30-second sampling rate data; however the coseismic
displacement for the individual main shock cannot be resolved.We thus adopt
the kinematic positioning technique using 1-second sampling rate (1 Hz) data
to determine the individual coseismic displacements for each main shock as
well as the evolution of the ground shaking. The results show only three
stations near the epicenters with significant total coseismic displacements
of 3-5 centimeters. We find that the stations farther north of the
epicenters area indeed reveal significant coseismic displacements but moving
in the opposite direction between the two main shocks. The coseismic
displacement of the first main shock is consistent with a NNE-trending
normal faulting in the lower crust offshore of southern Taiwan, while that
of the second main shock likely agrees with an ENE-trending right-lateral
strike-slip faulting, although the possibility of a NNW-trending
left-lateral strike-slip faulting cannot be ruled out. The 1 Hz GPS data can
record the coseismic ground shaking in great detail, including the first
motion direction and the amplitude and arrival time, which are comparable to
the seismometer data. By applying an exponential attenuation behavior with
hypocenter distance we observe that four stations in the coastal plain
exhibit relatively larger amplitudes of the ground shaking, implying a
significant influence of thick unconsolidated deposits in that area.
Keywords: GPS, CORS, Coseismic deformation, Seismic ground shaking, Pingtung Earthquake.
Citation: Chen, H. Y., J. C. Lee, L. C. Kuo,
S. B. Yu, and C. C. Liu, 2008: Coseismic surface GPS displacement and ground
shaking associated with the 2006 Pingtung earthquake doublet, offshore
southern Taiwan. Terr. Atmos. Ocean. Sci., 19, 683-696, doi:
10.3319/TAO.2008.19.6.683(PT)
|
FULL ARTICLE DOWNLOAD |
DATA NOTE |