Abstract <p>Quaternary sediment subsidence in the Red River Delta has been quietly occurring for 1600 ka BP. This paper introduces the causes, mechanisms, and rates of tectonic subsidence and subsidence due to sediment compression in three boreholes selected for detailed study: BH4-HN, BH02-HP, and BH56-ND, representing three key areas of the Red River Delta. The activities of the northwest-southeast co-sedimentary fault systems and the northeast-southwest post-sedimentary fault systems have created a weak subsidence zone in Hanoi and two strong subsidence zones in Hai Phong and Nam Dinh. The results of sequence stratigraphy analysis show that these 3 boreholes all have 5 sequences: (1) <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\text{Q}}_{1}^{1}\)</EquationSource> <!--LitMin2660014Tran-m1--> </InlineEquation>: Early Pleistocene; (2) <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\text{Q}}_{1}^{{2{\text{a}}}}\)</EquationSource> <!--LitMin2660014Tran-m2--> </InlineEquation>: Early middle Pleistocene; (3) <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\({\text{Q}}_{1}^{{2{\text{b}}}}\)</EquationSource> <!--LitMin2660014Tran-m3--> </InlineEquation>: Late middle Pleistocene; (4) <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\({\text{Q}}_{1}^{{3{\text{a}}}}\)</EquationSource> <!--LitMin2660014Tran-m4--> </InlineEquation>: Early late Pleistocene; (5) <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\({\text{Q}}_{1}^{{3{\text{b}}}}\)</EquationSource> <!--LitMin2660014Tran-m5--> </InlineEquation>-Q<sub>2</sub>: Late late Pleistocene-Holocene. These 5 sequences are related to 5 glacial/interglacial cycles. Each sequence has 3 sedimentary systems tracts: lowstand (LST), transgressive (TST), and highstand (HST) systems tracts. The sequences and system tract of the 3 boreholes were calculated for the total of tectonic subsidence rate and sediment compression rate as follows: BH4-HN has Vav of 0.281 mm/year, BH02-HP: 0.63 mm/year, and BH56-ND: 0.799 mm/year. This has shown that the two strong subsidence zones of Hai Phong and Nam Dinh cause the strong estuaryization process at the Bach Dang estuary and the strong erosion of the Hai Hau coast.</p>

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Causes, Mechanisms and Rates of Land Subsidence in the Red River Delta and Warnings of Excessive Groundwater Exploitation

  • Nghi Tran,
  • Thu Trinh Hoai,
  • Renat Shakirov,
  • Natalia Sokolova,
  • Huong Tran Thi Thuy,
  • Nam Le Dinh,
  • Toan Ngo Quang,
  • Thanh Dinh Xuan,
  • Nhuan Do Van,
  • Thao Nguyen Thi Phuong,
  • Anh Bui Thi Bao,
  • Hang Pham Thi Thu,
  • Tung Nguyen Xuan

摘要

Abstract

Quaternary sediment subsidence in the Red River Delta has been quietly occurring for 1600 ka BP. This paper introduces the causes, mechanisms, and rates of tectonic subsidence and subsidence due to sediment compression in three boreholes selected for detailed study: BH4-HN, BH02-HP, and BH56-ND, representing three key areas of the Red River Delta. The activities of the northwest-southeast co-sedimentary fault systems and the northeast-southwest post-sedimentary fault systems have created a weak subsidence zone in Hanoi and two strong subsidence zones in Hai Phong and Nam Dinh. The results of sequence stratigraphy analysis show that these 3 boreholes all have 5 sequences: (1) \({\text{Q}}_{1}^{1}\) : Early Pleistocene; (2) \({\text{Q}}_{1}^{{2{\text{a}}}}\) : Early middle Pleistocene; (3) \({\text{Q}}_{1}^{{2{\text{b}}}}\) : Late middle Pleistocene; (4) \({\text{Q}}_{1}^{{3{\text{a}}}}\) : Early late Pleistocene; (5) \({\text{Q}}_{1}^{{3{\text{b}}}}\) -Q2: Late late Pleistocene-Holocene. These 5 sequences are related to 5 glacial/interglacial cycles. Each sequence has 3 sedimentary systems tracts: lowstand (LST), transgressive (TST), and highstand (HST) systems tracts. The sequences and system tract of the 3 boreholes were calculated for the total of tectonic subsidence rate and sediment compression rate as follows: BH4-HN has Vav of 0.281 mm/year, BH02-HP: 0.63 mm/year, and BH56-ND: 0.799 mm/year. This has shown that the two strong subsidence zones of Hai Phong and Nam Dinh cause the strong estuaryization process at the Bach Dang estuary and the strong erosion of the Hai Hau coast.