Measuring the restless Earth
Issued: Tue, 18 Sep 2012 17:06:00 BST
The Geomatics Group in the School of Geographical and Earth Sciences combine science and advanced technology to enhance our understanding of the constructive and destructive processes of the Earth's surface.
Dr Zhenhong Li, Senior Lecturer, specialises in the precise location and determination of surface movements of the Earth – a field of research known as geodesy. His research interests include the use of Interferometric Synthetic Aperture Radar (InSAR) and Global Positioning Systems (GPS) to monitor changes in the Earth’s surface over time.
‘We aim to use advanced geodesy technology to address scientific questions relating to natural hazards, such as landslides, tsunami and earthquakes,’ says Dr Li. ‘I spend half of my research time on the technique itself, where my aim is to improve the accuracy and reliability of the technology.’ The other half of his time is spent on different applications, for example looking at specific landslides and earthquakes, locating city subsidence, and locating engineering subsidence due to mining activities and high-speed railways.
InSAR is a powerful technique for monitoring any changes in the Earth’s surface, and has recently been shown to produce results far more quickly than and just as reliably as fieldwork. During the 2010 Yushu earthquake in China, Dr Li was able to pinpoint its location and surface movements within just hours after receiving satellite radar images using InSAR technology, with comparable and fully consistent results from the field taking weeks to achieve.
Monitoring subsidence and uplift
‘We also want to use this technology to monitor building subsidence and railway stability,’ says Dr Li, who is working closely with local government in China to look at mining subsidence. ‘In Shenfu there is a big problem of subsidence due to mining activity but the government previously had no idea how serious the issue was. Now, after my project, they have a clear idea of how serious the subsidence issue is in North China.’
Dr Li is also monitoring city subsidence in Eastern China related to groundwater extraction by factories.
The applications of Dr Li’s research are wide-reaching, and he collaborates internationally with research groups in Europe, China and the USA. Because his technology improves precision and enhances the potential of satellite monitoring and data processing, it allows other users from diverse fields to improve the accuracy of their own data.
He has recently used his technology to monitor mountain uplift at a rate of just 1.6mm per year, the first time such slow movement has been detected using geodesy technology.
Geodesy is a field with exciting new opportunities for postgraduates. ‘Anyone with skills in programming, or a background in mathematics or physics, should get in touch,’ says Dr Li. ‘They can work with me to advance our technology, and we can apply geodesy techniques to help us understand earthquakes, landslides and tsunami in the future.’
Find out more