Remote Sensing of Environment 218 (2018) 221–230 Contents lists available at ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse Deformation of Linfen-Yuncheng Basin (China) and its mechanisms revealed by Π-RATE InSAR technique T ⁎ Chaoying Zhaoa,b, , Chuanjin Liua,c, Qin Zhanga,b, Zhong Lud, Chengsheng Yanga,b a School of Geology Engineering and Geomatics, Chang'an University, No.126 Yanta Road, Xi'an 710054, China b National Administration of Surveying, Mapping and Geoinformation, Engineering Research Center of National Geographic Conditions Monitoring, Xi'an 710054, China c The Second Monitoring and Application Center, China Earthquake Administration, Xi'an 710054, China d Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX 75275, USA ARTICLE INFO ABSTRACT Keywords: The Linfen-Yuncheng Basin (LYB) in China is a region possessing severe geo-hazards, including active tectonic InSAR fault movement, land subsidence and ground fissures among others. Interferometric Synthetic Aperture Radar Fault (InSAR) technique is applied to map surface deformation associated with various geo-hazards in this basin. The Subsidence poly-interferogram rate and time-series estimator algorithm (Π-RATE) is used over forty-nine scenes of SAR data Ground fissure to generate the deformation maps over the entire LYB. The precision of InSAR results is around 3 mm/yr. Some Deformation active faults and ground fissures are successfully detected. The spatiotemporal characteristics of tableland uplift, Linfen-Yuncheng Basin (LYB) Poly-interferogram rate and time-series faults displacement and basin subsidence are quantitatively monitored with InSAR technique ranging from estimator algorithm (Π-RATE) 2 mm/yr to 142 mm/yr. Finally, the mechanisms of surface deformation regarding large scale Zhongtiaoshan fault, middle scale basin land subsidence and small scale ground fissures are discussed in terms of interseismic movement, underground water level changes and hydrostratigraphic heterogeneity. 1. Introduction superimposed by clusters of ground fissures, and Hejin is suffering from abnormal surface subsidence and uplift (Yang et al., 2016; Ji et al., The Linfen-Yuncheng Basin (LYB) is located in the south-central 2016). So, how can basin-scale deformation be efficiently and precisely Shanxi graben system, where the tectonic formation is extremely monitored? Is it possible to separate different hazard deformation fields complex with frequent seismic events (Liu and Ji, 2014; Wang, 1995) from each other? And what are the mechanisms of the complex hazards (Fig. 1). Historically, more than ten earthquakes with magnitude (M) in LYB? These are the research questions that we attempt to address in larger than 7.0 have occurred in this basin, including the M 8 Hongtong this paper. earthquake in 1303 and M 7.5 Linfen earthquake in 1695. The most Conventional ground-based geodetic techniques, such as GPS and recent significant earthquake was an M 4.4 event near Yuncheng on leveling, have been applied to monitor the fault movements in LYB Mar. 12, 2016. Two large-scale piedmont normal faults control LYB, (Hao et al., 2016; Liu et al., 2016; Cui et al., 2016). However it is dif- namely the Luoyunshan fault (LYF) to the northwest and the Zhong- ficult to detect detailed and comprehensive ground deformation due to tiaoshan fault (ZTF) to the southeast. These faults slip at a rate as large their low spatial resolution. In contrast, InSAR can provide surface as 2 mm/yr, as monitored by campaign leveling and GPS measurements deformation measurement at meter-scale spatial resolution. Pre- (Hao et al., 2016; Cui et al., 2016). While, long-term inter-seismic liminary results of the land subsidence in LYB during 2008–2010 have movement estimated by radiocarbon (14C) dating has shown the mean been previously reported (Yang et al., 2016). This research addressed slip rate of the Northern ZTF is 0.75 ± 0.05 mm/a since 24.7 ka BP (Si several challenges in applying InSAR techniques, such as decorrelation et al., 2014), no quantitative measurement has been done on small and in the farmland and mountainous regions, and tropospheric delay ar- secondary normal faults, which strike mainly to the northeast-east and tefacts. In addition, data from both C-band Envisat and L-band ALOS-1 east-west within the LYB. Little is known about buried faults in the PALSAR were exploited to enhance deformation measurements. So, this region. In addition, four large historical land subsidence areas have research is fourfold: (i) large coverage surface deformation mapping been recorded in LYB: Yaodu district at Linfen, Jishan County, Taocun- using multi-frame, multi-track SAR data, (ii) comparison of InSAR re- Xiaxian, and Hejin (Yang et al., 2016). The first three areas are also sults from multiple sensors with different headings, looking angles and ⁎ Corresponding author at: School of Geology Engineering and Geomatics, Chang'an University, No.126 Yanta Road, Xi'an 710054, China E-mail address: [email protected] (C. Zhao). https://doi.org/10.1016/j.rse.2018.09.021 Received 7 August 2017; Received in revised form 23 August 2018; Accepted 24 September 2018 0034-4257/ © 2018 Elsevier Inc. All rights reserved. C. Zhao et al. Remote Sensing of Environment 218 (2018) 221–230 Fig. 1. Shaded relief Map of the Linfen-Yuncheng Basin (LYB). Red polygons show the coverage of the three SAR tracks, grey dashed line outlines the area of LYB, and black lines show the active normal faults. The epicenters of earthquakes with magnitude greater than M 4 that occurred from 1831 BCE to 2016 are shown with purple circles. The inset shows the location of LYB. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) wavelengths, (iii) InSAR results from different tracks and sensors were 2. Geological setting then merged for basin-wide deformation analysis of the entire LYB by considering the relative offsets in the overlapped regions and the ab- 2.1. Geomorphology solute offsets, as determined by leveling and GPS measurements, and (iv) interpretation of the mechanisms of different deformation fields In Fig. 1, LYB is bounded by the Lvliang Mount to the northeast and within the LYB at a variety of spatial scales. the Zhongtiao Mount to the southwest. Taer Mount, Emei tableland, 222 C. Zhao et al. Remote Sensing of Environment 218 (2018) 221–230 Mingtiaogang tableland are located in the center of LYB. Fen River, a large branch of the Yellow River, goes through the basin and merges into the main stream of the Yellow River to the west of the basin. 2.2. Quaternary deposits The quaternary deposits in LYB are as thick as 490 m, composed of four series: lower Pleistocene (Q1), middle Pleistocene (Q2), upper Pleistocene (Q3) and Holocene (Q4). The sedimentary thicknesses for these four series range from 10 to 400 m, 45 to 202 m, 3 to 65 m, and 0 to 20 m, respectively. In each series, the sedimentary thickness varies greatly from the edges to the center of the basin. 2.3. Faults Three kinds of tectonic faults exist in LYB according to the char- acteristics and spatial scales, including major piedmont faults at the edges of the basin, boundary faults within the basin between different geomorphology units, and some hidden faults. As shown in Fig. 1, the major piedmont faults include the 120-km-long LYF, bounding the north of the LYB along a NNE direction, and the 137-km-long ZTF bounding the south of the LYB with a similar distribution trend to the LYF. These two major faults can be divided further into 5 and 3 sec- tions, respectively, according to the variations in strike, dip angle, slip rate etc. The Huoshan piedmont fault with NS trend and 60 km in length is located in the Linfen sub-basin (Fig. 1). Two tableland faults Fig. 2. Flowchart of different scale deformation analysis with Π-RATE InSAR include the North Emei fault (NEF) and South Emei fault (SEF). These method. faults represent the south boundary of Linfen sub-basin and the north boundary of Yuncheng sub-basin. The lengths of these two faults are Interferograms are routinely processed using GAMMA InSAR soft- 85 km and 130 km, and the trends are NEE and NEE ~ NE, respectively. ware. To improve the coherence, a big multi-looking number was set for In addition, five faults with lengths ranging from 30 to 50 km are dis- Envisat and ALOS data to obtain a final pixel size as large as 80 m, tributed within the Linfen sub-basin; these faults delimitate the small- respectively. Topographic effect in the interferograms was removed scale grabens and tablelands within the sub-basin. Finally, the LYB using a 30-m Shuttle Radar Topography Mission Digital Elevation contains many hidden faults, including 27 that can be inferred in the Model (SRTM DEM) (Farr et al., 2007). Linfen sub-basin and another 8 in the Yuncheng sub-basin (Meng, 2011). This indicates the Linfen sub-basin is more tectonically complex 4. Methodology than the Yuncheng sub-basin. In order to accurately map the absolute deformation field over 3. SAR data and interferogram formation multi-tracks SAR data coverage region, the poly-interferogram rate and time-series estimator algorithm (Π-RATE) was firstly applied for each To monitor the surface deformation in the LYB, archived SAR individual SAR data. Then InSAR results from different tracks and imagery data acquired from 2007 to 2011, including C-band Envisat/ sensors were merged for basin-wide deformation analysis of the entire ASAR data by the European Space Agency (ESA) and L-band ALOS/ LYB by considering the relative offsets in the overlapped regions and PALSAR data acquired by JAXA were processed. Firstly, spatial baseline the absolute offsets, as determined by leveling and GPS measurements.