GNSS atmopheric seismology: A case study of the 2008 Mw7.9 Wenchuan earthquake

Abstract

Robust seismic signals around the globe could estimate the gross nature of earthquakes, but the details are usually unclear due to the lack of near-field observations. Although ground measurements, e.g., GNSS/InSAR and strong motion measurements, provide unique insights on the kinematic rupture and nature of the earthquake, but the temporal-spatial resolutions are still limited. In this paper, GNSS atmospheric seismology is proposed and a case study of the 2008 Wenchuan earthquake is performed using ground GNSS measurements. Significant ionospheric disturbances are found at continuous GNSS sites near the epicenter with an intensive N-shape shock-acoustic wave propagating south-eastward, almost consisting with seismometer, indicating that the co-seismic ionospheric TEC disturbances were mainly derived from the main shock. Furthermore, the co-seismic tropospheric anomalies during the mainshock are also found, mainly in the zenith hydrostatic delay component (ZHD), which is supported by the same pattern of surface observed atmospheric pressure changes at co-located GNSS site that are driven by the ground-coupled air waves from ground vertical motion of seismic waves propagating. Therefore, the co-seismic atmospheric disturbances indicate again the acoustic coupling effect of the atmosphere and solid-Earth with air wave propagation from the ground to the top atmosphere.