SATELLITE TEAM reveal Sichuan earthquake ground distortion through satellite radar interferometry

Australian experts are assisting Chinese authorities with the analysis of dramatic satellite images of ground distortions of up to five metres following the May 12 Sichuan earthquake. The image analysis project is critical in assessing the magnitude of quake-induced ground movement and the potential for further landslips and damage to structures. The most recent aftershock collapsed 420,000 houses and injured dozens in south-west China on Tuesday. Led by Chinese-born Associate Professor Linlin Ge, the UNSW based team was among the first expert groups in the world to generate a ground displacement map, and is the only group supplying analysis direct to the Chinese authorities. Associate Professor Ge said the Chinese Earthquake Authority can overlay the images provided onto satellite photos to assess damage around buildings or bridges.	Satellite interferograms from Assoc Prof Ge's website dedicated to the earthquake studies
“The larger the ground deformation, the more likely the structures will be damaged,” he said. The team's analysis is taken from satellite images captured on May 20 by the Japanese ALOS satellite, which orbits the Earth every 46 days. Detailed satellite imagery could play a critical role in reducing earthquake casualties if additional satellites were deployed to capture images more frequently, according to Associate Professor Ge. Given the two to three day build-up of pressure before land slides, a purpose-built network of satellites orbiting every two days could predict slope failure and anticipate aftershocks by picking up even small ground movements, he said. “When you see cracks in the ground that can be too late – with remote sensing you have more time to raise the alarm or evacuate.” Associate Professor Ge said the Chinese space agency is due to launch a new radar satellite which will orbit the Earth every four days. China has plans to launch 100 satellites by 2020, about 20 per cent of which will be radar capable, he said. Last year, the Cooperative Centre for Spatial Information entered into a landmark research agreement, negotiated by Associate Professor Ge, with China’s Centre for Earth Observation and Digital Earth, at the Chinese Academy of Sciences, to strengthen China’s capacity for earth observation, mapping and monitoring of ground displacement. Associate Professor Ge’s position is jointly funded by the NSW Dept of Lands, the Cooperative Research Centre for Spatial Information (CRCSI) and UNSW.
Further information: CRCSI media backgrounder Dr Linlin Ge A/Professor School of Surveying & Spatial Information Systems The University of New South Wales Project Leader and Senior Research Fellow Cooperative Research Centre for Spatial Information Visiting Professor New South Wales Department of Lands Deputy Director CRCSI-CEODE Joint Centre for Spatial Information Ph: 02 9385 4177, M: 0423 287 219