Investigating Active Deformation in the Northern Longitudinal Valley and City of Hualien in Eastern Taiwan Using Persistent Scatterer and Small-Baseline SAR Interferometry

Abstract

Rapid convergence between the Eurasian plate and the Philippine Sea plate in the northern Longitudinal Valley near the city of Hualien in eastern Taiwan has produced prominent fault scarps and large earthquakes (M ≥ 7). This study attempts to more thoroughly understand the surface deformation activities near the faults and their relation to earthquakes near Hualien City using a stable target, multi-temporal radar interferometry method to extract the surface deformation information in this area. Our results indicate that the extracted deformation signals were comparable with those in our leveling data and have a very high spatial density (exceeding 70 point km -2 ). Additionally, all faults in the northern Longitudinal Valley and Hualien City were not deformed monotonically. Rather, deformation time series are complex and frequent activities affected the general trends wherein, for example, 2005 earthquake swarm produced more than 10 mm of displacement near the Milun fault. Moreover, deformation rates in the study area generally ranged from around 10 -20 mm yr -1 of relative displacement rates along the radar line of sight between the western part of Hualien City near the Central Range and the eastern part during the decade, while only the Mingyi fault displayed monotonic fault activities with change of displacement rates of approximately 5 -10 mm yr -1 across the fault.

Campaigned GPS on Present-Day Crustal Deformation in Northernmost Longitudinal Valley Preliminary Results, Hualien Taiwan

“…9f and g) indeed exhibit different types of surface deformation. The northern part of the area, especially the Milun Tableland, revealed significant movement during the period across the Chi-Chi earthquake, which appears similar to the influence of the 2005 earthquake swarm observed in PSI analysis (Yen et al 2011). During the 1995 -1998 period the E -W AA' stacking interferogram I (Fig.…”

“…We also paid particular attention on the deformation across the Milun fault. Hereafter we first present a recently published PSInSAR study from the ENVISAT satellite to illustrate the accumulated vertical deformation from (Yen et al 2011. We then present our DInSAR study from the ERS satellite for the 1995-1998-2000deformations.…”

“…Comparing the SRD rate and cumulative number of earthquakes, we interpret that there was significant slip (accommodated by micro-earthquakes) on the deeper part of the Milun fault in 1998 -2000, possibly triggered by the great Chi-Chi earthquake. After the Chi-Chi influence, we anticipate that the surface deformation would come back to the normal interseismic rate, with exceptions during occasional local earthquake swarms, for example the 2005 swarm mentioned above (Yen et al 2011). …”

Surface deformation in the Himalaya and adjoining piedmont zone of the Ganga Plain, Uttarakhand, India: Determined by different radar interferometric techniques

“…4b). These stable back-scatterers are called the ''Persistent Scatterers (PS)'' points (Hooper et al, 2004(Hooper et al, , 2007Chang et al, 2010;Yen et al, 2011). In general, these PS points can be either man-made or natural such as buildings, tree trunk, rock outcrops or boulders (Hooper et al, 2004).…”

Geostatistical Data Fusion of Multiple Type Observations to Improve Land Subsidence Monitoring Resolution in the Choushui River Fluvial Plain, Taiwan

“…Over the years, precise leveling, global positioning system (GPS) and interferometric synthetic aperture radar (InSAR) have proven to be powerful techniques in the field of geodesy. Many studies have applied these techniques for land subsidence monitoring and prediction (Reilinger et al 1977;Dixon 199l;Yu and Chen 1994;Galloway et al 1998;Massonnet and Feigl 1998;Ferretti et al 2001;Sato et al 2003;Chang et al 2004;Hooper et al 2004Hooper et al , 2007; Galloway and Burbey 2011; Yen et al 2011;Wu et al 2013). …”