Seasonal, long-term, and short-term deformation in the Central Range of Taiwan induced by landslides

Abstract

Seasonal movement of GPS stations is often attributed to hydrological loading and other environmental factors. For the first time we observe seasonal motion associated with slow-moving landslides. Eight of 26 continuous GPS (cGPS) sites in the Central Range of Taiwan show long-term landslide-induced motion at rates of ~3-15 mm/yr, ~20%-60% of their tectonic interseismic velocities. The directions of movements after heavy rains and in the wet season are consistent with the slope directions derived from a high-resolution elevation model constructed by airborne lidar. Long-term and seasonal interseismic motions are modulated by slow-moving landslides. Seasonal motions of landslides at Lushan show peak to peak amplitudes of ~3-19 mm.Estimates of interseismic crustal strain can be biased if surface processes are not taken into account. Preliminary analyses indicate that rainfall and topography play strong roles in the occurrence of landslides. Discrimination between surface processes and motion that has a tectonic origin is the key to natural hazard assessments. INTRODUCTIONTime series of GPS station positions recorded by the Taiwan continuous GPS (cGPS) array reveal profound seasonal variations, with ampli-

Hierarchical Cluster Analysis of Dense GPS Data and Examination of the Nature of the Clusters Associated With Regional Tectonics in Taiwan

“…For K = 9, a single station in the mountain range is isolated as a cluster (Figure S1h, labeled as LC, black). The data might be contaminated by local and seasonal effects such as landslides due to the heavy rainfall (e.g., Hsu et al, ).…”

Self‐Entrainment Motion of a Slow‐Moving Landslide Inferred From Landsat‐8 Time Series

“…As a consequence, the study of slow-moving landslides may lead a better understanding of the physical processes governing both slow and rapid landslides (Palmer, 2017). In recent years, various studies of slow-moving landslides (e.g., Bennett et al, 2016;Handwerger et al, 2013Handwerger et al, , 2015Hsu et al, 2014;Iverson & Major, 1987;Lacroix et al, 2014Lacroix et al, , 2015Reid, 1994;Schulz et al, 2009;Zerathe et al, 2016) have revealed a rich diversity in kinematics, with various forcing factors, for example, rainfall, earthquakes, glacial retreat, and anthropogenic activity. These forcings act over a wide variety of timescales, from seconds (earthquakes Lacroix et al, 2014) to several decades (glacial retreat Strozzi et al, 2010), thus making their study challenging.…”

“…Landslide motion is often interpreted to occur as a direct consequence of external forcing factors (e.g., Handwerger et al, 2013Handwerger et al, , 2015Hsu et al, 2014;Lacroix et al, 2014;Reid, 1994;Zerathe et al, 2016), such as rainfall or ground shaking (i.e., from earthquakes). However, different internal processes may also influence landslide motion; for example, progressive failure is thought to play a key role in the initiation of landslide motion (Amitrano, 2004;Carey & Petley, 2014;Eberhardt et al, 2004;Gischig et al, 2016;Lacroix & Amitrano, 2013).…”

Total Variation Regularization of Geodetically Constrained Block Models in Southwest Taiwan

“…We select 267 CGPS stations that have continuously recorded more than 5 years of data and with data covered more than 70% of a year. We do not include stations located near areas subject to seasonal slow-moving landslide area in the Central Range (Hsu et al, 2014).…”