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Scientists LOOK at the Sky to Detect Tsunamis

05-06-2017

A team of scientists from Sapienza University in Rome, Italy, and NASA's Jet Propulsion Laboratory in Pasadena, California, have developed a new algorithm to detect tsunamis before they reach the coastline.

The so-called “Varion Alogorithm” (Variometric Approach for Real-time Ionosphere Observation), which uses GPS and other satellite navigation system information to detect disturbances in the ionosphere related to tsunamis, was developed under the guidance of Mattia Crespi, Lecturer in Positioning and Geomatics at the Sapienza Faculty of Civil and Industrial Engineering by Giorgio Savastano, a young Sapienza PhD student in Geodesy and Geomatics and Pasadena Jet Propulsion Laboratory Partner (JPL). The work, financed by both by Sapienza and JPL, was recently published on “Scientific Reports” of Nature. 

The ionosphere is the layer of the earth’s atmosphere that stretches from 80 to 1000 km over the surface of the Earth. Its ionisation is caused by solar and cosmic radiation and is mainly known as the cause of the aurora borealis. A tsunami moving across the ocean also moves the air above it, creating gravity waves. As the atmosphere grows thinner higher up in the atmosphere, these gravity waves grow larger. And by the time they reach 350 km into the atmosphere, their width is large enough to cause profound changes in the ionosphere’s electronic density. These changes can be measured using a GNSS signal, like that of global positioning systems (GSPS) crossing the ionosphere.

Savastano, who was awarded a two-month scholarship at JPL in 2015 from the National Council of Engineers (CNI) and ISSNAP (Italian Scientists and Scholars in North America Foundation), worked at JPL with a team studying the ionosphere through remote sensing supervised by Attila Komjathy and Anthony Mannucci. “Varion is an innovative contribution for a tsunami warning integrated system,” explains Savastano. “We are working to implement the algorithm in the JPL GNSS Network that provides real-time data from 230 stations around the world. These stations store data from several satellite systems, including GPS, Galileo, Glonass and BeiDou.”

Savastano claims that Varion can be used within a tsunami detection system and functions with data from diverse sources, such as seismometers, buoys and GNSS receptors. Once an earthquake is detected, the system begins monitoring the ionosphere electron content in real-time to identify anomalies linked to tsunamis. These measurements can then be stored and analysed by a control centre, which will generate risk-maps on specific seismic events.