Ionospheric detection of gravity waves induced by tsunamis

Tsunami waves propagating across long distances in the open-ocean can induce atmospheric gravity waves by dynamic coupling at the surface. In the period range 10 to 20 minutes, both have very similar horizontal velocities, while the gravity wave propagates obliquely upward with a vertical velocity of the order of 50 m s^(−1), and reaches the ionosphere after a few hours. We use ionospheric sounding technique from Global Positioning System to image a perturbation possibly associated with a tsunami-gravity wave. The tsunami was produced after the M_w= 8.2 earthquake in Peru on 2001 June 23, and it reached the coast of Japan some 22 hours later. We used data from the GEONET network in Japan to image small-scale perturbations of the Total Electron Content above Japan and up to 400 km off shore. We observed a short-scale ionospheric perturbation that presents the expected characteristics of a coupled tsunami-gravity wave. This first detection of the gravity wave induced by a tsunami opens new opportunities for the application of ionospheric imaging to offshore detection of tsunamis

Tomographie de l'ionosphère et de la troposphère à partir des données GPS denses (applications aux risques naturels et amélioration de l'interférométrie SAR)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Ionospheric remote sensing of the Denali Earthquake Rayleigh surface waves

International audienceUsing the Global Positioning System, we have detected ionospheric disturbances associated with the long-period Rayleigh waves from the 2002 Denali earthquake (M s = 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

Ground-based GPS imaging of ionospheric post-seismic signal

International audienceDuring the Demeter mission, a continuous global positioning system (GPS) ionospheric tomography above Europe, Japan and California will be performed with the Service and Products of ionosphere Electronic Content and Tropospheric Refractive index over Europe (SPECTRE) experiment. The main goal of the conducted observations is to detect and characterize post-seimic ionospheric perturbations associated to seismic generated waves, more precisely near field seismic waves, far field Rayleigh waves and tsunamis. We first review the theory describing post-seismic ionospheric signals as well as the most recent observations of these signals. We then present the description of the tomographic procedure used for the SPECTRE experiment, as well as the obtained tomographic models. We finally draw the perspective of such observations