Seismic monitoring using the telecom fiber network

TL;DR

This study demonstrates that laser interferometry applied to telecommunication fiber networks can effectively detect and analyze earthquakes, offering a scalable, remote seismic monitoring method suitable for dense urban and remote regions.

Contribution

The paper presents the first large-scale implementation and validation of fiber-optic seismic sensing, establishing detection relations and spectral analysis techniques for earthquake monitoring.

Findings

Successful detection of a broad range of earthquake magnitudes

Quantitative relations between detection probability, magnitude, and distance

Spectral analysis provides insights into earthquake dynamics

Abstract

Laser interferometry enables to remotely measure microscopical length changes of deployed telecommunication cables originating from earthquakes. Long range and compatibility with data traffic make it unique to the exploration of remote regions, as well as highly-populated areas where optical networks are pervasive, and its large-scale implementation is attractive for both Earth scientists and telecom operators. However, validation and modeling of its response and sensitivity are still at an early stage and suffer from lack of statistically-significant event catalogs and limited availability of co-located seismometers. We implemented laser interferometry on a land-based telecommunication cable and analyzed 1.5 years of continuous acquisition, with successful detections of events in a broad range of magnitudes, including very weak ones. By comparing fiber and seismometer recordings we determined relations between a cable's detection probability and the magnitude and distance of events, and showed that spectral analysis of recorded data allows considerations on the earthquake dynamics. Our results reveal that quantitative analysis is possible for this sensing technique and support the interpretation of data from the growing amount of interferometric deployments. We anticipate the high integration and scalability of laser interferometry into existing telecommunication grids to be useful for the daily seismicity monitoring, in perspective exploitable for civilian protection use.