Terr. Atmos. Ocean. Sci., Vol. 19, No. 6, 589-594, December 2008 |
doi: 10.3319/TAO.2008.19.6.589(PT) |
Earthquake Doublet Sequences: Evidence of Static
Triggering in the Strong Convergent Zones of
Taiwan
Cheng-Horng Lin,1,* Yih-Hsiung
Yeh,1 Kuang-Jung
Chen,2 and Hsin-Chieh Pu
3
1.
Institute
of
Earth Sciences
,
Academia Sinica
2. Department of Earth Sciences,
National
Taiwan
Normal
University
3. Institute of Geophysics, National Central University
Abstract
Three
earthquake sequences, each with two main earthquakes of almost the same
magnitudes (ML
from 5.9 to 7.0 with differences less than
0.1), have recently been observed in Taiwan. The two largest earthquakes in
each sequence occurred with a short delay time between them, were strikingly
similar in terms of magnitude, location and/or focal mechanism and are
referred to as doublets. They were markedly distinct from typical single
mainshock sequences. Our estimated static stress field generated by the
first shock in the doublet shows that the second shock and most of their
aftershocks were located within a region where static stress increased
substantially. Thus, a possible explanation for earthquake doublet is that
seismic energy for each shock had accumulated independently within adjacent
crustal volumes, separated by an asperity, and that the second shock is
triggered by the increased static stress after the first one. An important
implication of doublet sequence is that works by emergency response teams
after the first earthquake could be made more hazardous by the second.
Keywords: Doublet earthquake, Static triggering, Aftershocks
Citation: Lin, C. H., Y. H. Yeh, M. Ando, K.
J. Chen, T. M. Chang, and H. C. Pu, 2008: Earthquake doublet sequences:
Evidence of static triggering in the strong convergent zones of Taiwan.
Terr. Atmos. Ocean. Sci., 19, 589-594, doi: 10.3319/TAO.2008.19.6.589(PT)
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