dc.description.abstract | Earthquake Source Scaling of Moderate to Large Earthquakes in Taiwan:
Study of 2003 Mw>6 Taiwan Earthquakes
Hsin-I Lin
Abstract
We inverted velocity data from broadband array in Taiwan (BATS)to
study earthquake source parameters of three Mw>6 earthquakes in
eastern Taiwan in 2003. These earthquakes occurred in June 9th, June 10th
and Dec 10th, 2003, respectively. We use least-square method to invert the
distribution of slip and other source parameters. The slip distribution and
aftershocks were used to estimate the fault geometry. For each event, we
derived a preferred model by testing different focal mechanisms. In order
to have a batter azimuthal coverage to the earthquake, one Japanese
station from F-net was used, in addition to the BATS stations.
These earthquakes are all thrust faulting mechanisms. The hypocenter
of June 9th earthquake is 24.4oN, 121.99oE at the depth of 21.3 km. The
focal mechanism has the strike, dip, and rake of 225o, 26 o, and 121 o,
respectively. The moment is 8.65*1024 dyne-cm, which yields the Mw of
5.89. The main rupture is around hypocenter, and ruptured toward
northeast direction. The June 10th earthquake occurred at 23.52oN
121.67oE, at the depth of b5.7 km. The focal mechanism has the strike,
dip, and rake of 217 o, 39 o, and 110 o, respectively. The moment is
2.03*1025 dyne-cm, which yields the Mw of 6.13. It ruptured toward
northeast in downdip direction. The September 10th earthquake was
occurred at 23.07oN 121.40oE at a focal depth of 17.7 km. The focal
mechanism has the strike, dip, and rake of 3 o, 42 o, and 104 o, respectively.
The moment is 2.68*1025 dyne-cm, which yields the Mw of 6.22.
According to the slip and aftershocks distributions, this earthquake is
believed to be associated with the Chihshang fault.
We collected the results and other recent research of Taiwan
earthquakes, to obtain the relationship of earthquake magnitude (Mw) to
fault length (L2), fault area (A2) and average slip (D2). The relations
among the source parameters are as follow:
5 . 4 ) log( 4 . 1 2 + = L Mw ,
5 . 4 ) log( 8 . 0 2 + = A Mw ,
7 . 3 ) log( ) 45 . 0 3 . 1 ( 2 + ± = D Mw ,
For better understanding of earthquake source characteristics in Taiwan
region, threes scaling relationships provided important information for
seismic hazard analysis. | en_US |