Modern vertical deformation rates and mountain building in Taiwan from precise leveling and continuous GPS observations, 2000–2008

Abstract

[1] To characterize the present-day vertical displacement field in the active Taiwan orogenic belt, 1843 precise leveling and 199 continuous GPS measurements from 2000 to 2008 are collected and analyzed in this study. Vertical velocities derived from the leveling data are placed in a reference frame of the Chinese continental margin using continuous GPS observations at nearby sites. The leveling and GPS vertical velocities generally reveal a dome-shaped pattern with uplift of ∼0.2-18.5 mm/yr in the interior of the mountain range and subsidence on the flanks of the mountains and coastal plains. Modern uplift rates in the active fold and thrust belt are generally consistent with geologic uplift rates. However, present-day uplift rates in the Central Range are faster than the million-years-averaged exhumation rates. The modern subsidence rates are generally consistent with geologic rates, except for the rates in western coastal areas due to groundwater pumping. Present-day subsidence in the southern Central Range and northern Coastal Range is, however, inconsistent with long-term uplift, which may reflect interseismic elastic strain accumulation across faults. Present-day subsidence in northern Taiwan occurs in a region of postcollisional orogenic collapse. We model the present-day and geologic vertical velocities and published GPS horizontal velocity data across southern Taiwan using a 2-D lithospheric model. The model suggests a combined slip rate of 40 mm/yr on the frontal thrusts and 45 mm/yr on the Longitudinal Valley fault. The model requires an additional source of crustal thickening under the Central Range to match the observed present-day uplift rates.

Thick-Skinned and Thin-Skinned Tectonics: A Global Perspective

“…Generally speaking uplift rates are highest in the Backbone and Central Ranges and drop off to subsidence towards the east (Eastern Range) and the west (Western Foothills and Western Coastal Plain). The modern uplift rates are comparable to long-term geological uplift rates except for the Central Range where modern uplift rates are much higher [114]. The modern subsidence rate in the Eastern Range in the transect of Figure 11a is in contradiction with the geologic vertical velocity rate (uplift) and might be due to interseismic elastic deformation according to [114].…”

“…The modern subsidence rate in the Eastern Range in the transect of Figure 11a is in contradiction with the geologic vertical velocity rate (uplift) and might be due to interseismic elastic deformation according to [114]. Subsidence in the Western Foothills and Western Coastal Plain is explained as resulting from long-term elastic loading of the Eurasian Plate by the Taiwan thrust belt and the withdrawal of water [114].…”

“…A compilation of the data on active uplift (and subsidence) of Taiwan can be found in [114]. The curve shown in Figure 11A (top) represents a projection of these data gathered along strike of the cross-section farther south and north.…”

“…To explain the dome shaped uplift pattern of the Taiwan thrust belt [114] suggested a model with a thrust fault along the décollement level of the Western Foothills extending into the crystalline basement beneath the Backbone and Central Ranges. Results from analog modeling also suggest such a scenario [57].…”

“…Earthquake cluster after [110], seismic energy release data after [105], earthquake foci 2016 retrieved from Central Weather Bureau Seismic Network of Taiwan (CWBSN). Uplift rates constructed from [114]. …”