Ionospheric seismology: from Earth to Venus?
Séminaires Planétologie et Sciences Spatiales
522, bât. Lamarck
The surface conditions of Venus, in particular the very high temperature (>700 K), are too extreme to operate a long-lived seismic station with available technology. For this reason, it is interesting to explore the possibility of using remote-sensing methods for ionospheric seismology, which have been successfully applied on Earth over the last decades. The basic principle is that seismic and tsunami waves couple with the atmosphere and are amplified at high altitude; when these waves reach the ionosphere, they induce fluctuations in remotely observable quantities, such as the total electron content or the airglow emission. In the case of Venus, the seismic coupling with the atmosphere is more efficient than on Earth by a factor of about 70, due to the high atmospheric density. Thus, a significant amount of energy would be transmitted to the atmosphere after a quake. Here, we model and analyze this coupling mechanism based on normal-mode computations. Synthetic seismograms in the high atmosphere are then used to derive the induced fluctuations in two different infrared airglow emissions, located between 90 km and 150 km above the surface. The possibility of detecting this signal with an orbiting airglow camera is explored, and scientific implications in terms of measuring the seismicity of Venus and its interior structure are discussed.