Seismology with optical links: enabling a global network for submarine earthquake monitoring

TL;DR

This paper demonstrates that existing optical fibre telecommunication links can be used to detect seismic events, including submarine earthquakes, over thousands of kilometres, enabling a potential global real-time underwater earthquake monitoring network.

Contribution

It introduces a novel method using optical fibre links and frequency metrology techniques for seismic detection, extending the range beyond current reflectometry-based methods.

Findings

Detected earthquakes over 75 to 535 km optical fibre links.

Able to monitor seismic activity up to 18,500 km from epicentres.

Potential to establish a global underwater earthquake detection network.

Abstract

Earthquake monitoring across the globe is currently achieved with networks of seismic stations. The data from these networks have been instrumental in advancing our understanding of the Earth's interior structure and dynamic behaviour. However, almost all seismic stations are located on land and earthquakes of magnitude smaller than 4 at the bottom of the oceans remain largely undetected. Here we show that ordinary telecommunication optical fibre links can detect seismic events when combined with state-of-the-art frequency metrology techniques. We have detected earthquakes over terrestrial and submarine optical fibre links with length ranging from 75 to 535 km and a geographical distance from the earthquake's epicentre ranging from 25 to 18,500 km. In contrast to existing commercial reflectometry-based acoustic sensing methods used widely in the oil and gas industry, which are limited to only a few tens of kilometres, the technique presented here can be extended over thousands of kilometres, paving the way for detection of remote underwater earthquakes. By using the proposed technique on the existing extensive submarine optical fibre infrastructure, which already criss-crosses the seas and oceans, a global seismic network for real-time detection of underwater earthquakes could be implemented. The ability to detect off-shore earthquakes closer to the source could also enable a cost-effective solution for early detection of tsunamis.