Multi-GNSS and single-station localization of coseismic ionospheric disturbance sources
Abstract
Monitoring large earthquakes to rapidly forecast their consequences remains a challenging task, especially in areas far from seismological and geodetic networks. Meanwhile, large and shallow earthquakes induce specific changes in Total Electron Content (TEC), commonly detected and monitored today using Global Navigation Satellite Systems (GNSS). The sudden Earth's surface motions act as a powerful acoustic source. The triggered acoustic pressure wave propagates toward the upper atmosphere and strongly affects the ionosphere. To address the sparsity issue, we assess the ability of a single GNSS receiver to constrain the coseismic ionospheric disturbances (CID) source location. We first show that the CID signature is sensitive to the acoustic source location with the help of a complete modelling. We then perform a grid search strategy to test how well a synthetic CID perturbation from different trial source points on the Earth's surface fit the observed series. The multiple sounding of the ionosphere by multi-constellation GNSS satellites allows such trilateration. A first synthetic study confirms that a higher number of monitoring satellites locates the source with better precision. We also illustrate how a favourable geometrical coverage enhances the accuracy of the solution. Then, we apply the method on real data acquired after two distinct earthquakes in Turkey in 2011 (Mw 7.1) and New-Zealand in 2016 (Mw 7.8). The surface deformation is well constrained by seismo-geodetic studies. In both cases, we are able to retrieve the acoustically coupled area within 50 km from the maximum of the surface deformation. This result is consistent with the generation mechanisms of coseismic acoustic waves. In conclusion, our study suggests that even a very sparse network of multi-GNSS receivers can provide an independent estimate of large scale co-seismic motions. This can be particularly useful offshore coastal regions where satellites that image the ground deformation cannot operate and onshore geodetic networks lack resolution.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.719Z