Three underwater fiber-optic cables offshore of central Chile

The F1 network code includes selected broadband velocimetric data collected from three DAS instruments of the OptoDAS type, manufactured by ASN (Alcatel Submarine Networks). These instruments interrogate three underwater fiber-optic cables offshore of central Chile, spanning 400 km (from 5 m above sea level to 2000 m below sea level).

The original DAS data is recorded as strain rate, with a spatial sampling interval of 15 m, resulting in 26,664 virtual sensors along the fibers. Two instruments operate at a sampling rate of 62.5 Hz, while one operates at 100 Hz.

Downsampling and conversion to velocity are performed directly on the instruments. The resulting network delivers single-component broadband ground velocity measurements every 5 km, yielding a total of 80 virtual stations.Real-time transmission is made through a SeedLink protocol in the MiniSEED format from the instruments. The metadata complies with the FDSN MiniSEED 2.6 norm.

This project is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 101041092 – ABYSS). It involves a close collaboration with the Chilean Centro Sismológico Nacional (CSN) and the University of Chile.