Experimental geometry of GPS measurements during the Wenchuan earthquake on 12 May 2008. Gray star shows the epicenter’s location. Isolines of Peak Ground Velocity are presented by thin lines near the epicenter. Location of the SIPs for the selected GPS sites and GPS satellite numbers LUZH-14, LUZH-22 and XIAG-05 at the moments of maximum of TEC deviation is shown by thick dots; solid line triangle represents the D1 GPS array we used. Location of all used GPS sites is marked by shaded triangles. Gray line and arrow show the plane wave front and wave vector of excited shock-acoustic wave. Thin curves show the motion of SIPs in the northwest (DLHA-05) and the northeast (XIAA-12) direction from epicenter. The projection of magnetic field vector B to Earth’s surface is shown by a dotted grey arrow.