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 continuousGlobal Positioning System (cGPS) stations observations over the period 2010-2015.Results demonstrate significant SVCM in Yunnan with annual cyclic movements as thedominant pattern, the mean annual cyclic amplitude and initial phase is 9.7 mm and2.9 months, respectively. These annual cyclic movements exhibit a high degree of spatialuniformity as a whole, while some spatial differences exist across regions. GPS seasonalvertical time-series show strong consistency with GRACE (Gravity Recovery andClimate Experiment) data, providing further indication that regional deformation exerts adominant effect on the GPS vertical time-series. Over the period, the Yunnan area featuredsubstantial precipitation that shows significant annual periodicity and a strong correlationwith the GPS vertical time-series. The seasonal precipitation is therefore concluded to bethe regional dominant factor that governs vertical cyclic crustal movements in this area. Differencesin topography and precipitation between western and eastern Yunnan (i.e. acrossthe Jinshajiang-Red River Fault) result in a greater magnitude of SVCM in western Yunnancompared to that in eastern Yunnan. Vertical linear movement rates of Yunnan derived fromGPS also exhibit evident differences between eastern and western Yunnan. Therefore, resultssuggest that the Red River Fault is an important factor in the spatial variability of verticalcrustal movements in Yunnan.