11:30 AM - 11:45 AM
[J04-6-05] Inversion of tsunami and sea level uplift from GNSS-TEC: toward a breakthrough for tsunami monitoring systems?
Ionospheric signals associated to atmospheric gravity waves generated by near and far field tsunamis are now routinely detected as well as acoustic waves generated by near-source ocean or solid earth uplift.
Complete modeling of these signals can be done especially with solid/ocean/atmosphere coupled normal-mode summation which allows to model the tsunami amplitude not only in the ocean layer, but also in the atmosphere and ionosphere. This captures all the coupling and most of the physics of the propagation, including effects due to atmospheric local time, oceanic bathymetry and atmospheric wave attenuation.
We show here that 1D waveform inversions of the ionospheric signals model the tsunami sea levels variations with very high accuracy. These inversions based on tsunami normal-mode summations model the sea level vertical displacement close to the ionospheric piercing point of the GPS receiver-satellite pair and can therefore be compared to DART data. Inversions were therefore made for several tsunamis (2012 Haida Gwai, 2006 Kuril, 2011 Tohoku), in either far or near field. Statistics demonstrate the error of the inversion to be less than 10% of the peak-to-peak amplitude of the tsunami. These first results open important perspectives for densifying global tsunami monitoring systems, by offering tsunami height measurement in any fixed location equipped with a dual GPS system or even from mobile platforms, such as boats and aircrafts.
Recent modeling shows in addition that the acoustic pulse generated by large earthquakes not only reaches the ionosphere above the quake in less than 8-10 minutes, but provides a direct measurement of the vertical amplitude as well as the projection of the Earth or ocean affected surface.
These advances in the ionospheric inversions and the further developments of GNSS constellations will complement the existing surface seismic, geodetic and ocean systems and will likely improve future regional and global tsunami warning systems.
Complete modeling of these signals can be done especially with solid/ocean/atmosphere coupled normal-mode summation which allows to model the tsunami amplitude not only in the ocean layer, but also in the atmosphere and ionosphere. This captures all the coupling and most of the physics of the propagation, including effects due to atmospheric local time, oceanic bathymetry and atmospheric wave attenuation.
We show here that 1D waveform inversions of the ionospheric signals model the tsunami sea levels variations with very high accuracy. These inversions based on tsunami normal-mode summations model the sea level vertical displacement close to the ionospheric piercing point of the GPS receiver-satellite pair and can therefore be compared to DART data. Inversions were therefore made for several tsunamis (2012 Haida Gwai, 2006 Kuril, 2011 Tohoku), in either far or near field. Statistics demonstrate the error of the inversion to be less than 10% of the peak-to-peak amplitude of the tsunami. These first results open important perspectives for densifying global tsunami monitoring systems, by offering tsunami height measurement in any fixed location equipped with a dual GPS system or even from mobile platforms, such as boats and aircrafts.
Recent modeling shows in addition that the acoustic pulse generated by large earthquakes not only reaches the ionosphere above the quake in less than 8-10 minutes, but provides a direct measurement of the vertical amplitude as well as the projection of the Earth or ocean affected surface.
These advances in the ionospheric inversions and the further developments of GNSS constellations will complement the existing surface seismic, geodetic and ocean systems and will likely improve future regional and global tsunami warning systems.