Large differential land subsidence and earth fissures in Jiangyin,China |
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| Authors: | G Y Wang Greg Guanlin You B Shi S L Wu J Q Wu |
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| Institution: | (1) Geological Survey of Jiangsu Province, 210018 Nanjing, China;(2) School of Science and Engineering, University of Ballarat, University Drive, Mt Helen, Ballarat, VIC, 3353, Australia;(3) Department of Geoscience, Nanjing University, 210093 Nanjing, China; |
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| Abstract: | Jiangyin County is in the infamous Su–Xi–Chang land subsidence area caused by excessive groundwater withdrawal in Jiangsu
province, China. The maximum accumulated land subsidence reached 1,310 mm near the centre of the subsiding trough in 2006
in southern Jiangyin, and earth fissures of significant vertical offsets have been observed at Changjing, Hetang and Wenlin
which form an arc towards the subsidence trough. An ancient Yangtze River course is found underlying and passing through the
depression in southern Jiangyin, forming a local basin surrounded by outcropped bedrock ridges in the north and south. The
Quaternary stratigraphy demonstrates significant heterogeneities in the basin; the second confined aquifer is much thicker
and deeper and encapsulated inside the basin and absent above the ridges. The development of earth fissures along the Changjing–Hetang–Wenlin
arc might be a combination of an inward rotation of sediments due to a large differential subsidence, an inward movement driven
by seepage force and a steeper slope along the south-eastern shoulder of the basin that facilitates the development of horizontal
tensile strain and/or shear strain necessary for fissuring. The land subsidence has slowed down and no new earth fissure zone
has occurred in the area after the banning of deep groundwater extraction was enacted in 2001. |
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