Change in deformation pattern on the Hengchun peninsula after 2006 Pingtung earthquake doublet and activity of the Hengchun fault
Date Issued
2015
Date
2015
Author(s)
Hu, Wan-Lin
Abstract
Taiwan is situated in the active arc–continent collision region between the Philippine Sea plate and Eurasia plate. The destructive earthquakes induced from active structures could poses threats on infrastructures such as the 3rd Nuclear Power plant, which is seated close to the Hengchun fault in Hengchun Peninsula, southernmost of Taiwan. Thus, understanding the activity of the Hengchun fault and seismogenic potential is a crucial topic on assessment of the seismic hazards. On the decadal time scale geodetic observation, previous studies suggested that the surface uplift rate on Hengchun peninsula based on leveling measurements was changed significantly after the 26th December 2006 Pingtung offshore earthquake doublet.The uplift rate across the Hengchun fault can be 2-3 times than the original rate. Furthermore, the changed slip pattern lasted for 3-6 years. In order to verify the hypothesis of triggering relationship between 2006 Pingtung earthquake doublet and the influence on crustal deformation in the surrounding fault systems, we adopt Coulomb static stress change model to characterize the deformation occurred on the Hengchun fault. The results indicate Hengchun fault fall in the stress increasing zone, providing a plausible evidence for the hypothesis of static stress transfer. Furthermore, the elastic half-space dislocation model is used to forward slip distribution on the Hengchun fault and find the best-fit fault parameter as well as the slip distribution on the fault patches associated with the surface deformation. Moreover, in this study, we attempt to apply ERS (C-band) and ALOS (L-band) satellite-based Persistent Scatterers SAR Interferometry (PS-InSAR), in the duration of the 1996-2000 and 2006-2010 respectively, to detect regional crustal deformation patterns. Six profiles perpendicular to the Hengchun fault are made to analyze the relationship between deformation and active structures. A dome-shaped deformation pattern between western Hengchun fault and Hengchun Valley is coincide with the mud diaper inferred from geological survey and seismic profile. The results suggest that the mud diapirism should play an important role on the deformation on Hengchun Peninsula.
Subjects
Hengchun Fault
Crustal deformation
Dislocation model
Coulomb static stress transfer
Type
thesis