InSAR, Earthquake and Ionosphere
Xiaoli Ding1, W. Zhu1, B.C. Zhang1, J. Hu1,2, L. Zhang1, G.C. Feng2, Z.W. Li2
1. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic
University, Hung Hom, Kowloon, Hong Kong, China
2. School of Geosciences and Info-Physics, Central South University, Changsha, China
Abstract
It is well known that the conditions of the ionosphere, a layer of the atmospheric at attitude
from about 50 km to over 1,000 km vary both in time and space due primarily to solar
activities such as the occurrence of sunspots and solar flares. In addition, anomalous
ionospheric variations also occur with geophysical activities such as some major earthquakes.
The conditions of the ionosphere and their variations can significantly affect space geodetic
measurements such as those of GPS and spaceborne InSAR as the signals of these geodetic
systems travel through the ionosphere. The ionospheric signatures in space geodetic
measurements also provide important information for studying the conditions of the
ionosphere, the variations of the conditions, and the associated physical processes such as
earthquakes.
This talk focuses on some recent research results on determining ionospheric signatures, such
as ionospheric anomalies associated with earthquakes, based on InSAR measurements and on
modeling and removing ionospheric effects on InSAR measurements. It is found that the high
spatial resolution InSAR measurements can be used to map in great detail the ionospheric
anomalies associated with earthquakes, providing important insight into the phenomena. It is
also vitally important to remove the effects of the ionospheric effects from InSAR
measurements in applications such as co-seismic deformation measurements with InSAR in
order to avoid the significant biases caused by the effects. Methods that have been developed
for the estimation of ionospheric phase screen for correcting InSAR measurements will be
discussed.
Short Biography
Dr. Xiaoli Ding is Chair Professor of Geomatics and Head of Department of Land Surveying
and Geo-Informatics at The Hong Kong Polytechnic University. Prof. Ding obtained his BEng
from the Central South University of Metallurgy, China in 1983 and his PhD from the
University of Sydney in 1993. He lectured at the Northeast University of Technology, China
(1983 - 1986) and Curtin University (1992 - 1996), before joining the Hong Kong Polytechnic
University in 1996. His main research interests are in developing technologies for studying
ground and structural deformation and geohazards, with a current focus being upon space
borne geodetic technologies such as GPS and InSAR. He has published about 150 peer
reviewed journal papers in these research fields. He is a Fellow of the IAG.