Abstract
Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions. The potential to leverage the existing fiber optic seafloor telecom cables that criss-cross the oceans, by using them as dense arrays of seismo-acoustic sensors, remains to be evaluated. Here, we report Distributed Acoustic Sensing measurements on a 41.5 km-long telecom cable that is deployed offshore Toulon, France. Our observations demonstrate the capability to monitor with unprecedented details the ocean-solid earth interactions from the coast to the abyssal plain, in addition to regional seismicity (e.g., a magnitude 1.9 micro-earthquake located 100 km away) with signal characteristics comparable to those of a coastal seismic station.
Highlights
Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions
Data were acquired from February 19th to February 24th, 2018, on a 41.5 km long electro-optic telecommunication cable from Alcatel, which is deployed offshore Toulon in the south of France
This cable is the backbone of the MEUST-NUMerEnv project[17] (Mediterranean Eurocentre for Underwater Sciences and Technologies—Neutrino Mer Environnement) (Fig. 1)
Summary
Two thirds of the surface of our planet are covered by water and are still poorly instrumented, which has prevented the earth science community from addressing numerous key scientific questions. The potential to leverage the existing fiber optic seafloor telecom cables that crisscross the oceans, by using them as dense arrays of seismo-acoustic sensors, remains to be evaluated. Permanent seafloor observatories for longterm monitoring[3], comprised of multi-physics platforms connected to land by an electro-optic cable, are very costly to install and maintain[4], which limits their spatial extent, density, and scope These different approaches have enabled significant discoveries, our observations below the oceans’ surface and sea-bottom remain limited. One breakthrough was the coincidental discovery that earthquakes can be detected by analyzing the phase stability of state-of-the-art lasers across thousand-kilometer-long seafloor telecommunication cables[6] This approach only provides one measurement, which is integrated over the entire length of the cable. Notwithstanding strong expectations[15] and one reported earthquake detection[16], the performance of DAS on submarine telecom cables remains to be evaluated to better define its range of possible applications
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