Present-day kinematics of active mountain building in Taiwan from GPS observations during 1995–2005

Abstract

[1] We characterize the kinematics of modern crustal deformation in Taiwan and evaluate the potential for large earthquakes by computing tectonic block motions and fault slip rates from 531 GPS horizontal velocities. These new GPS velocity field indicates that lateral extrusion in the southern transition from collision to subduction is primarily achieved by motion along several major reverse faults and internal distortion of blocks. The northern transition is characterized by asymmetric opening of the Okinawa trough and collision-induced rotation between the Ryukyu trench and Okinawa trough. We suggest that the differences in style of deformation in northern and southern Taiwan are a result of differences in trenchward motions between the overriding plate and forearc sliver. Along-strike variations in basin thickness and the presence of foreland basement obstacles in central Taiwan result in clockwise rotation with sinistral motion on faults and counterclockwise rotation with dextral motion on faults north and south of the obstacle, respectively. In eastern Taiwan, high slip rate of ∼43 mm/yr on the southern Longitudinal Valley fault (LVF) is responsible for the full collision of Taiwan orogeny. E-W syn-orogenic extension in the southern Central Range has been inferred by our model. Patches with high slip rate deficits on the LVF and the Chelungpu fault from our model, respectively, mainly correspond to the source areas of the 1951 M 7.1 Longitudinal Valley earthquake sequence and of the 1999 M w 7.6 Chi-Chi earthquake.

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

“…In fact, the crustal movement behavior in northeastern Taiwan, from Ilan to the Hualien area, has been interpreted as the result of tectonic extrusion plus possible additional nearby back-arc opening effects (Lu et al 1995;Hu et al 2002;Rau et al 2008;Angelier et al 2009;Ching et al 2011). The southernmost part of the extruded block in those studies is considered located near the village of Hoping, which is about 25 -30 km north of Hualien City.…”

“…1a) accommodates the present surface horizontal shortening of 2 -3 cm yr -1 , which is about one-third of the 8.2 cm yr -1 tectonic contraction across the whole Taiwan mountain belt (Biq 1965;Ho 1986;Yu et al 1990; Lee and Angelier 1993;Angelier et al 1997;Yu et al 1997;Lee et al 2003). On the northern and southern tips of the NNE-trending Taiwan mountain belt, the Ilan and Pingtung plains, show both lateral tectonic escape and/or horizontal strata bending with a rather complex combination of deformation features, such as block rotation, strike-slip faulting (i.e., shearing) and normal faulting (i.e., extension) (Angelier et al 1990;Lu et al 1995;Rau et al 2008;Angelier et al 2009;Ching et al 2011). Recently, Rau et al (2008) and Ching et al (2011) analyzed GPS data and illustrated a significant plate-corner rotation occurring south of the Ilan plain area in northeastern Taiwan.…”

“…On the northern and southern tips of the NNE-trending Taiwan mountain belt, the Ilan and Pingtung plains, show both lateral tectonic escape and/or horizontal strata bending with a rather complex combination of deformation features, such as block rotation, strike-slip faulting (i.e., shearing) and normal faulting (i.e., extension) (Angelier et al 1990;Lu et al 1995;Rau et al 2008;Angelier et al 2009;Ching et al 2011). Recently, Rau et al (2008) and Ching et al (2011) analyzed GPS data and illustrated a significant plate-corner rotation occurring south of the Ilan plain area in northeastern Taiwan. Although the rates derived from their studies are slightly different, both of them interpreted it as a result of block rotation induced by Philippine Sea plate indentation into the Chinese continental margin, significantly enhanced by southward opening (pull-apart) of the Okinawa trough.…”

Tiechanshan-Tunghsiao anticline earthquake analysis: Implications for northwestern Taiwan potential carbon dioxide storage site seismic hazard

“…1). Where the anticline is situated northwestern Taiwan is considered a basin-controlled salient judging from the along-strike variation in the Neogene basin thickness (Lacombe et al 2003) located at the northernmost end of the active contraction zone in Taiwan (Shyu et al 2005;Ching et al 2011). The TCS-TH anticline creation is dated ~0.5 Ma based on the ages of the Pleistocene Toukoshan formation growth strata and the tilted terraces on the fold (Mouthereau and Lacombe 2006).…”

“…1). As a consequence, the earthquakes recorded during the last two decades are rather diffuse in response to the low crustal strain rate in this part of Taiwan (Rau et al 2008;Ching et al 2011). In spite of the lack of background seismicity, northwestern Taiwan experienced a devastating M 7.1 Hsinchu-Taichung earthquake sequence in 1935 (Fig.…”