Present-day interseismic surface deformation along the Longitudinal Valley, eastern Taiwan, from a PS-InSAR analysis of the ERS satellite archives

Abstract

[1] In Taiwan, about one third of the lithospheric plate convergence between Eurasia and the Philippine Sea plate is accommodated on the eastern coast across the narrow Longitudinal Valley (LV). The Longitudinal Valley Fault (LVF) is the main seismically active fault zone in this region. However, the spatial distribution of ground deformation due to interseismic loading on locked fault segments remains widely unknown. To address this problem, we use a "permanent scatterer" (PS) interferometric synthetic aperture radar (InSAR) approach for processing the ERS satellite archives. The PS mean velocity maps allow accurately mapping and quantifying the ground deformation all along the LV. Assuming that, close to the surface, the fault plane along the central LVF creeping segment dips 55°to the east, we derive a slip vector at the surface of ∼25 mm/yr with a mean rake of 70°. In agreement with our PS observations, shallow seismicity indicates a clear change in the fault mechanical behavior of the creeping segment around Fuli town. Finally, we propose a combination of the PS velocity fields for estimating a 3-D map of ground deformation. In the southern part of the LV, the vertical component reveals an uplift of the Coastal Range with respect to the LV of ∼10 mm/yr. Moreover, between Taitung and Luyeh, the vertical deformation is essentially accommodated along the Luyeh Strand. Finally, north of Rueisuei, the Coastal Range uniformly subsides at ∼15 mm/yr relative to the western side of the LV. However, a local uplift pattern is detected around latitude 23°42′.Citation: Peyret, M., S. Dominguez, R. Cattin, J. Champenois, M. Leroy, and A. Zajac (2011), Present-day interseismic surface deformation along the Longitudinal Valley, eastern Taiwan, from a PS-InSAR analysis of the ERS satellite archives, J. Geophys.

Interseismic Deformation and Earthquake Hazard along the Southernmost Longitudinal Valley Fault, Eastern Taiwan

“…According to the slip rates between the two strands, the strain partitioning at this latitude is not as simple as a transpressive model proposed by Lee et al (1998). Instead, our model results are more consistent with recent mapping results and field investigation (Shyu et al, 2008) and surface deformation from persistent scatterer interferometric synthetic aperture radar (PS-InSAR; Peyret et al, 2011).…”

“…On the Lungtien surface, the Luyeh strand has a dip-slip rate of 8:3 mm=yr, generating a smaller uplift rate than that suggested by leveling (Fig. 5) but more consistent with the uplifted rates derived from PS-InSAR (Peyret et al, 2011). However, topographic profiles (Fig.…”

Near-field strain observations of the October 2013 Ruisui, Taiwan, earthquake: source parameters and limits of very short-term strain detection

“…Furthermore, the Ruisui event may have ruptured the 25-30-km-wide transition zone between towns of Ruisui and Guangfu (see Fig. 5b) where no evidence of activity of the Central Range Fault had been reported by recent studies (Peyret et al 2011;Shyu et al 2005).…”

Testing the Influence of Static and Dynamic Stress Perturbations On the Occurrence of a Shallow, Slow Slip Event in Eastern Taiwan

“…It corresponds to a high‐angle east‐dipping listric fault characterized by high rates of oblique slip on its southern and central segments (e.g., Yu & Kuo, ). The fault is creeping at the surface at the rate of 1 to 3.5 cm/year between latitudes 23°00 ′ and 23°30 ′ (Champenois et al, ; L. Hsu & Bürgmann, ; Peyret et al, ) and also experiences seasonal and transient creep episodes (J. C. Lee et al, ; Murase et al, ). It has produced moderate to large earthquakes, which includes the 1951 M L 7.3 Taitung earthquake (Chen et al, ) and the 2003 M w 6.8 Chengkung earthquake (Ching et al, ).…”