Regional characteristics and influencing factors of seasonal vertical crustal motions in Yunnan, China

Abstract

Seasonal Vertical Crustal Motions (SVCM) in Yunnan are assessed from 27 continuous Global Positioning System (cGPS) stations observations over the period 2010–2015. Results demonstrate significant SVCM in Yunnan with annual cyclic movements as the dominant pattern, the mean annual cyclic amplitude and initial phase is 9.7 mm and 2.9 months, respectively. These annual cyclic movements exhibit a high degree of spatial uniformity as a whole, while some spatial differences exist across regions. GPS seasonal vertical time-series show strong consistency with GRACE (Gravity Recovery and Climate Experiment) data, providing further indication that regional deformation exerts a dominant effect on the GPS vertical time-series. Over the period, the Yunnan area featured substantial precipitation that shows significant annual periodicity and a strong correlation with the GPS vertical time-series. The seasonal precipitation is therefore concluded to be the regional dominant factor that governs vertical cyclic crustal movements in this area. Differences in topography and precipitation between western and eastern Yunnan (i.e. across the Jinshajiang–Red River Fault) result in a greater magnitude of SVCM in western Yunnan compared to that in eastern Yunnan. Vertical linear movement rates of Yunnan derived from GPS also exhibit evident differences between eastern and western Yunnan. Therefore, results suggest that the Red River Fault is an important factor in the spatial variability of vertical crustal movements in Yunnan.