1. University of Science and Technology of China, School of Earth and Space Sciences, Hefei, China and University of Science and Technology of China, Mengcheng National Geophysical Observatory, Hefei, China.
2. University of Science and Technology of China, School of Earth and Space Sciences, Hefei, China and University of Science and Technology of China, Mengcheng National Geophysical Observatory, Hefei, China. (corresponding author)
3. CNOOC Research Institute Ltd, Beijing, China.