Earthquake-induced gravitational energy change in Taiwan region: from
collision to Subduction
Chung-Liang Lo, Shu-Kun Hsu and Benjamin F. Chao
Institute of Geophysics, National Central University, Taiwan
The Taiwan active orogenesis has arisen from the strong convergence between the
northwest corner of the Philippine Sea Plate and the southeast margin of the Eurasian
Plate. The numerous earthquakes thus cause the eternal crustal deformation and
change the crustal gravitational potential energy (GPE). The calculation adopts the
PREM model and employs a direct solution approach to generate the integration of
coseismic GPE . In this study, we examine the earthquake-induced GPE in the
convergent plate boundary near Taiwan region by using regional earthquake
catalogues of Broadband Array in Taiwan Seismology (BATS) and global Harvard
CMT data catalogue. The result shows that the variation of the crustal GPE
strongly correlates with the different stages of the plate convergence. In Taiwan
collision zone, the crustal GPE can reflect the orogenesis as stages of initial
collision, active collision to post-collision, that is, the behavior of crustal GPE has
the spatial tendency from increasing to decreasing. In southwestern Ryukyu
subduction zone, the crustal GPE shows energy gain in the plate coupling zone
and energy loss in the fast back arc basin, namely Okinawa Trough rifting. In addition,
the GPE along the Ryukyu trench axis displays a segmentation anomaly implying
that the subduction along Ryukyu subduction zone is inhomogeneous.