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

Overview

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

• How does the regional landscape respond to tectonics and climatic drivers?
• What proportion of the seismic risk comes from landslides?
• 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 geomorphology and remote sensing, 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 landslide evolution to structural geology. 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. Funding permitting, a parallel project will apply similar approaches to the eastern part of the Ordos – the Shanxi Graben System.

The Ordos region of northern China has suffered three of the ten most deadly earthquakes in history: events in CE 1303, 1556 and 1920 killed ~1.4 M people between them (Figure 1). These earthquakes occur on faults which deform regions around the stable Ordos Block. The southwest part of the system is of particular interest, because it contains the transition between strike-slip, thrust and extensional faulting, near the location of the BCE 780 Qishan earthquake (Figure 1).

Click on an image to expand

Image Captions

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

Methodology

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.

There will also be the opportunity to study active fault systems in the region, which are unusual in that thrust, normal and strike-slip faults are developed in close proximity to each other. This provides the opportunity to explore how different fault types affect similar landscapes.

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

Project Timeline

Year 1

Initial training in techniques, processes and research methods. Selection of, and focus on an initial scientific problem, to act as a case study and opportunity for training in the preparation of a research paper.

Year 2

Expansion of the project into additional areas and techniques, including approaches for numerical modelling. Fieldwork in collaboration with the CEA (who have indicated their logistic support). Presentation of interim results at national and international conferences. Comparison of Ordos results with global examples of active fault systems

Year 3

Detailed analysis of remote sensing data and comparison with fieldwork results. It is anticipated that CEA datasets for radiocarbon dating of co-seismic deposits will be available for interpretation by this time.

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 2021 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.

Further Information

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

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