Active tectonics of the Shanxi Graben System

Overview

The project aims to study deformation and landscape responses associated with historic earthquakes and late Cenozoic extension across the Shanxi Graben System, which forms the eastern part of the larger Ordos rift system in northern China (Figure 1). Results will be relevant to global processes of continental extension. 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. Funding permitting, a parallel project will apply similar approaches to the western part of the Ordos.

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. Research focusses on historic earthquakes for which there are clear landscape expressions of co-seismic fault scarps, landslides and offset streams. All of these features provide constraints on fault and earthquake behaviour.

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 extensional terrains. High resolution digital elevation models and fieldwork will allow identification and study of young and active fault zones. There will be a focus on fault evolution at relay zones, initially located in Xu et al (2018).

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.

Year 3

Detailed analysis of remote sensing and fieldwork. Comparison of Shanxi results with global examples of active rifts. Development of models for regional rift evolution.

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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