Co-seismic ionospheric and deformation signals on the 2008 magnitude 8.0 Wenchuan Earthquake from GPS observations

Abstract

The 8.0 magnitude Wenchuan Earthquake occurred at the Longmenshan Fault along the eastern boundary between the Tibetan Plateau and the western Sichuan Basin in southwestern China on 12 May 2008, killing tens of thousands of people in several cities along the western Sichuan Basin. In this paper, co-seismic ionospheric and deformation signals from the mainshock of this event are extracted from national global positioning system (GPS) network observations, which provide unique insights into this event. The co-seismic deformation moves towards the earthquake epicentre, and the largest magnitude reaches 2.3 m in Beichuan. The total moment of the co-seismic rupture is 2.4 × 10²¹ nm, equivalent to a magnitude of 8.1 and nearly identical to the seismological estimate. Furthermore, co-seismic ionospheric disturbances indicate a shock-acoustic wave propagation at a mean velocity of about 600 m s⁻¹ towards the rupture direction.

Acknowledgments

We are grateful to those who created the Crustal Motion Observation Network of China and made the observation data available and Dr Z. Li who provided some early GPS results. This work was supported by a grant from the Key Project of the Chinese Academy of Sciences, the Korea Research Council of Fundamental Science & Technology funded by the Ministry of Education, Science and Technology in 2009, the SB RAS and FEB RAS collaboration project N 3.24, 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.