[1] Using the Global Positioning System, we have detected ionospheric disturbances associated with the long-period Rayleigh waves from the 2002 Denali earthquake (Ms = 7.9). The dense California GPS networks allowed us to map the ionospheric perturbations and to compute the group velocity with a high spatial resolution above the Pacific coasts. Due to a low sampling rate, a large error in the velocity determination remains. Nonetheless, it demonstrates that bi-static remote sensing measurements of seismic waves with GPS networks can be performed. Monostatic measurements with a dedicated satellite could possibly be used to record in the ionosphere surface waves originating from large earthquakes. Such a space-based remote sensing of the local group velocity of Rayleigh surface waves would effectively complement the seismic networks for high-resolution global tomography of the Earth's lithosphere.