Seismic monitoring using the telecom fiber network

Laser interferometry enables to remotely measure microscopical length changes of deployed telecommunication cables originating from earthquakes. Long reach and compatibility with data transmission make it attractive for the exploration of both remote regions and highly-populated areas where optical networks are pervasive. However, interpretation of its response still suffers from a limited number of available datasets. We systematically analyze 1.5 years of acquisitions on a land-based telecommunication cable in comparison to co-located seismometers, with successful detection of events in a broad magnitude range, including very weak ones. We determine relations between a cable's detection probability and the events magnitude and distance, introducing spectral analysis of fiber data as a tool to investigate earthquake dynamics. Our results reveal that quantitative analysis is possible, confirming applicability of this technique both for the global monitoring of our planet and the daily seismicity monitoring of populated areas, in perspective exploitable for civilian protection. Laser interferometry using existing telecommunication grids allows monitoring and quantitative investigation of daily seismic activity, according to the analysis of 1.5 years of continuous acquisition on a land-based telecommunication cable in Italy.