Ionospheric Total Electron Content tsunameter – ITEC

Too often, the existing tsunami warning systems cannot provide the direct tsunami measurements necessary for reliable (multi-point), local field (coasts less than two hours from the source) and global coverage warning. This is mainly due to the limited number of monitoring stations in the oceans. The main existing sensor network (DART) depends on surface buoys that are particularly costly to install and maintain, de facto limiting its capacity. However, this network has been greatly developed since the 2004 Sumatra-Andaman mega-tsunami, rising the awareness that a reliable tsunami warning depends on measurements of the wave in the middle of the ocean. But the simple fact that the DART network is limited to less than 50 measurement points for the entire globe highlights that it offers only partial protection against this natural hazard. As a result, the tsunami warning system continues to be regularly challenged. This was the case, for example, twice in 2018 in Indonesia.

Several recent studies have shown that it is possible to measure a tsunami by its imprint in the ionosphere, an upper layer of the atmosphere. Moreover, near-real-time monitoring of the ionosphere, and therefore of tsunami waves, can be done using GNSS satellite navigation systems, such as GPS and Galileo, and ground-based receivers. A system of this type that would depend only on terrestrial receivers would, like the DART network, be limited in its spatial coverage because the receivers are unevenly distributed throughout the world and limited to land areas. The ITEC project aims to fill this gap by developing a suitable GNSS receiver that is affordable, versatile and designed for deployment at sea, on existing buoys and/or vessels. The device will be designed to measure both the tsunami wave at ocean level and its signature in the ionosphere.

To implement this project, three development axes are planned: (1) improvement and testing of the ionospheric tsunami detection method, (2) implementation of real-time calculations and transmission on board the prototype, (3) design, integration and testing of the prototype in the laboratory and under real conditions. The prototype will combine a GNSS receiver and a miniature inertial sensor such as it can either integrate its own GNSS antenna or just adapt to the GNSS antennas already existing onboard buoys and ships. Thus, unlike the DART system, the future ITEC system is envisioned to be implemented quickly on a large scale and not limited to tsunamis initiated by strong earthquakes.