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Abstract
We registered near-field global positioning system (GPS) total electron content (TEC) response to the Wenchuan Earthquake on 12 May 2008. The Wenchuan Earthquake (magnitude 8.0) occurred at 06:28 UT as the result of motion on a northeast striking reverse fault (thrust fault) on the northwestern margin of the Sichuan Basin. The earthquake reflects tectonic stresses resulting from the convergence of crustal material slowly moving from the high Tibetan Plateau, to the west, against a strong crust underlying the Sichuan Basin and southeastern China. We found that intensive N-shaped shock-acoustic waves with a plane waveform and with a half-period of about 200 s propagated south-eastwards with a velocity 580 m s − 1 for a distance of about 1000 km from the epicentre. The wavefront of N-shaped disturbance was parallel with the earthquake rupture direction (from southwest to northeast). The main directional lobe of shock-acoustic wave emitter is directed southeastwards, i.e. transversely to the rupture. We speculate that the above properties of TEC response are determined by the geodynamics of the Wenchuan Earthquake. No noticeable TEC response to that earthquake was found in far-field regions in South Korea and Japan. We compared TEC response to the 2008 Wenchuan earthquake with other strong earthquakes.
Acknowledgments
The authors are grateful to S.V. Voeykov for help with primary data processing. The authors wish to thank members of the Crustal Movement Observation Network of China, the Geonet and the KGN networks for GPS data used in this paper. The work was supported by the interdisciplinary integral project of SB RAS N 56 ‘Seismoionospheric and seismoelectromagnetic processes in Baikal Rift Zone’, the RFBR-GFEN grant no. 06-05-39026 and RFBR grant no. 07-05-00127; by the Japanese Society for the Promotion of Science (JSPS); by the National Natural Science Foundation of China (grant no. 40774090 and grant no. 40636032); by the National Important Basic Research Project (2006CB806306) and the Korea Meteorological Administration Research and Development Program under grant no. CATER 2006–3104. The authors are grateful to Ramesh Singh for his comments and suggestions for improving the earlier version of the manuscript.