Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project.
Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent.
Ma
Kuo-Fong
KF
Department of Earth Sciences, National Central University, Chung-Li 32054, Taiwan. fong@earth.ncu.edu.tw
Tanaka
Hidemi
H
Song
Sheng-Rong
SR
Wang
Chien-Ying
CY
Hung
Jih-Hao
JH
Tsai
Yi-Ben
YB
Mori
Jim
J
Song
Yen-Fang
YF
Yeh
Eh-Chao
EC
Soh
Wonn
W
Sone
Hiroki
H
Kuo
Li-Wei
LW
Wu
Hung-Yu
HY