Abstract
We installed 10 continuous Global Positioning System (GPS) stations on the northeast margin of the Tibetan Plateau at the end of 2012, in order to qualitatively investigate strain accumulation across the Liupanshan Fault (LPSF). We integrated our newly built stations with 48 other existing GPS stations to provide new insights into three-dimensional tectonic deformation. We employed white plus flicker noise model as a statistical model to obtain realistic velocities and corresponding uncertainties in the ITRF2014 and Ordos-fixed reference frame. The total velocity decrease from northwest to southeast in the Longxi Block (LXB) was 5.3 mm/yr within the range of 200 km west of the LPSF on the horizontal component. The first-order characteristic of the vertical crustal deformation was uplift for the northeastern margin of the Tibetan Plateau. The uplift rates in the LXB and the Ordos Block (ORB) were 1.0 and 2.0 mm/yr, respectively. We adopted an improved spherical wavelet algorithm to invert for multiscale strain rates and rotation rates. Multiscale strain rates showed a complex crustal deformation pattern. A significant clockwise rotation of about 30 nradians/yr (10−9 radians/year) was identified around the Dingxi. Localized strain accumulation was determined around the intersectional region between the Haiyuan Fault (HYF) and the LPSF. The deformation pattern across the LFPS was similar to that of the Longmengshan Fault (LMSF) before the 2008 Wenchuan MS 8.0 earthquake. Furthermore, according to the distributed second invariant of strain rates at different spatial scale, strain partitioning has already spatially localized along the Xiaokou–Liupanshan–Longxian–Baoji fault belt (XLLBF). The tectonic deformation and localized strain buildup together with seismicity imply a high probability for a potential earthquake in this zone.
Highlights
Since the Middle Miocene, as a response to the India–Eurasia collision [1,2,3], the northeasternTibetan Plateau has been undergoing lateral extrusion, which is partially accommodated by sinistral strike–slip movement along the Haiyuan Fault (HYF) zone and crustal shortening toward the Tibet–Ordos transition zone of the northeastern margin along the Liupanshan area [4,5,6]
Using Global Positioning System (GPS) data from 58 continuous GPS (cGPS) stations over the period of 2010–2018, we presented an updated
We employed a color noise model to represent the statistical characteristic of coordinate surrounding areas
Summary
Since the Middle Miocene, as a response to the India–Eurasia collision [1,2,3], the northeastern. The tectonic deformation west of the Liupanshan (LPS) is characterized by numerous active strike–slip and thrust faults [10] The slip on these faults contributes to continuing uplift and seismic activity on the northeastern margin of the Tibetan Plateau [11]. The HYF and LPS are main boundary faults on the northeastern margin of the Tibetan Plateau, and are part of the most significant seismic hazard zone in the region [15]. On the south of the LPS, the Longxian–Baoji fault system (LXBJF) consists of four sub-faults, with the easternmost Qishan–Mazhao Fault (QSMZF) being the most active one, accommodating regional strain accumulation through strike–slip movement [17] In this area, other major faults are the north fringe fault of the West Qinling Mountains (NWQF) and the East Kunlun Fault (EKF) [6].
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