1. China University of Geosciences, Institute of Geophysics and Geomatics, Wuhan 430074, China and University of Lausanne, Institute of Earth Sciences, Lausanne 1015, Switzerland.(corresponding author).
2. University of Lausanne, Institute of Earth Sciences, Lausanne 1015, Switzerland..
3. China University of Geosciences, Institute of Geophysics and Geomatics, Wuhan 430074, China..