Active deformation and landscape evolution in the western Ordos, northern China

Overview

The project aims to study deformation and landscape responses associated with historic earthquakes and late Cenozoic deformation across the western part of Ordos rift system in northern China (Figure 1). Results will be relevant to global processes of continental deformation. Future earthquakes are a major development challenge, because of their capacity to cause huge damage. The project will address these research questions:

– How is faulting expressed in the regional landscape at different timescales?
– What is the seismic risk from the faults?
– What is the volume balance between tectonic uplift and erosion?

Data produced during the project will enhance knowledge of regional seismic risk, while the student will be trained in techniques in neotectonics and geomorphology, with application to other seismically active areas. The project is part of a continuing partnership with the China Earthquake Administration, which is the organisation within China tasked with earthquake mitigation in the country.
The project is strongly interdisciplinary, covering subjects from structural geology to loess geomorphology. The supervisors have track records of research and publication with project partners Dr Xu Yueren and Prof He Honglin. The student would join dynamic research communities in Earth Sciences in Durham and Glasgow. A parallel project is underway, that applies similar approaches to the eastern part of the Ordos – the Shanxi Rift System.

Click on an image to expand

Image Captions

Fig. 1: Active faults and selected major earthquakes, central/north China.

Methodology

The project will apply remote sensing and fieldwork techniques to identify and map causative fault segments in detail, and constrain earthquake parameters such as slip, orientation, length, magnitude, and, if possible, estimate the recurrence interval. Immediate landscape response to earthquakes would have included catastrophic landslides. Mapping these landslides will give quantitative estimates of regional co-seismic erosion and landslide risk in similar, future, earthquakes.

Regional landscape responses to faulting are recorded in both the overall topography and in river profiles. There are established techniques for analysing and interpreting both records. River profiles and their knickpoints hold long-term signals of fault throw and linkage in deformed terrains. Regional geomorphic indices such as the hypsometric index and surface index are perhaps less-used as tools for understanding landscape/tectonic interactions in extension, but the research team is applying them to convergent regions of deformation, in the India-Eurasia and Arabia-Eurasia collisions zones.

Fieldwork in China will allow participation in CEA palaeo-seismicity studies (fault trenching, sampling, radiocarbon dating).

Project Timeline

Year 1

Year 1 (October 2020 start): Initial training in techniques, processes and research methods. Selection of, and focus on an initial case study, with opportunity for training in the preparation of a research paper.

Year 2

Expansion of the project into additional areas and techniques, including potential approaches for numerical modelling. Fieldwork in collaboration with the CEA (who have indicated their logistic support).

Year 3

Presentation of interim results at national and international conferences. Comparison of Ordos results with global examples of active rifts. Landscape modelling using public domain codes such as FastScape or Landlab.

Year 3.5

Final interpretation of research findings; write-up of thesis and research papers.

Training
& Skills

The student will receive training in GIS and the programs necessary to manipulate and interpret large, remotely-sensed datasets. There will be training in tectonics and geomorphology, and in particular the approaches for interpreting patterns in both regional topography and drainage systems, and relating them to the underlying tectonic and climatic drivers. This suite of skills includes quantitative techniques developed by Martin Hurst at Glasgow University. Fieldwork skills will be included as required: it is intended to include a fieldwork component in 2022 in collaboration with the CEA. Additional training in research methods and scientific communication will be provided through a combination of Durham and Glasgow courses for postgraduates, and the central Iapetus provision.

The student will emerge from the PhD process with skills making them highly suited to a career in the Environmental Sciences, including the ability to manipulate and interpret large datasets. There are obvious career paths in natural hazards and land management, as well as further scientific research.

References & further reading

Xu, Y.R., He, H.L. Deng, Q.D. Allen, M.B., Sun, H.Y. & Bi, L.S. (2018) The CE 1303 Hongdong earthquake and the Huoshan Piedmont Fault, Shanxi Graben: Implications for magnitude limits of normal fault earthquakes. J. Geophysical Research, 123, 3098-3121.
Groves, K., Saville, C., Hurst, M.D., Jones, S.J., Song, S.G. & Allen, M.B. (2020) Geomorphic expressions of collisional tectonics in the Qilian Shan, north eastern Tibetan Plateau. Tectonophysics, 788. paper 288503, doi:10.1016/j.tecto.2020.228503

Further Information

Prof Mark Allen: m.b.allen@durham.ac.uk; tel: +44 (0)191 3342344.

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