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Monitoring of Tele-seismic Events Using Multiple Trans-oceanic Telecom Cables and Distributed Fiber Sensing

Description: 

We report the first demonstration of simultaneous measurement of teleseismic events on multiple operational telecommunication cables in the Atlantic and Pacific oceans. The total cable length exceeds 13,000km, creating a large-scale continuous deep-ocean seismic monitoring system with about 250 real-time stations. This is enabled by equipping each cable with a distributed fiber optic sensing (DFOS) prototype capable of measuring the integrated strain between each repeater (typically 40-80km) along the entire cable length. It is designed to be compatible with telecom traffic and does not impose any penalty in terms of bandwidth/performance. We form a roughly L-shaped array in the northern Atlantic by monitoring the 1770km IRIS subsea cable with 17 repeaters and a trans-Atlantic cable measuring about 6,500 km using around 120 repeaters. We also use a cable in the northern Pacific ocean with about 100 active repeaters. All cables are continuously monitored over a measurement period of several months.

Using several tele-seismic events, including the Dec 5th 2024 M7.0 earthquake in California, we analyze the response measured on each cable and compare it with land-based seismic stations close to the shore. We show the difference in sensitivity, both between separate cables as well as between different segments of the cable. Impact of cable deployment aspects on the sensitivity is investigated, showing that while each cable has areas with poor sensitivity, a substantial part of the available “sensors” record useful seismic data. We also provide quantitative analysis of the sensitivity of directionality of each cable. This is the first demonstration of simultaneous measurement of teleseismic events on multiple subsea cables in multiple oceans, showing that the technology is scalable beyond individual cables. The three cables used account for <1% of all cables world-wide, showing that DFOS over active telecom cables could be deployed to leverage hundreds of deployed telecom cables to create a global network with several thousands of stations on the ocean floor.

Session: Fiber-optic Sensing Applications in Seismology - I

Type: Oral

Date: 4/15/2025

Presentation Time: 09:00 AM (local time)

Presenting Author: Mikael

Student Presenter: No

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