Data to reproduce the figures in the Optica paper "Earth-Scale Precursors of the Kamchatka Earthquake Revealed via Polarization Monitoring in Undersea Mediterranean Optical Fiber Links" by A. Mecozzi et al.

Data and code to reproduce the figures in the Optica paper
A. Mecozzi et al., “Earth-Scale Precursors of the Kamchatka Earthquake Revealed via Polarization Monitoring in Undersea Mediterranean Optical Fiber Links,” Optica, https://doi.org/10.1364/OPTICA.586317

This repository provides the datasets required to reproduce the figures in the above Optica paper, together with MATLAB software to analyze and visualize them.

Data files

Each .mat file contains the measured transmission matrix in Jones space J (referred to as Jones matrix, from now on) and the corresponding Unix time vector time. The file names encode the start and end timestamps of the dataset.

• 2025-04-29T000000Z-2026-02-11T000000Z_CHA_ATH.mat
  Jones matrix J extracted at the Chania receiver of the Athens–Chania link, with corresponding Unix time time.
• 2025-03-01T000000Z-2026-02-11T000000Z_GEN_MAR.mat
  Jones matrix J extracted at the Genova receiver of the Marseille–Genova link, with corresponding Unix time time.
• 2025-04-20T000000Z-2026-02-11T000000Z_CAT_HAI.mat
  Jones matrix J extracted at the Catania receiver of the Haifa–Catania link, with corresponding Unix time time.
• 2025-03-03T000000Z-2026-02-11T000000Z_CAT_TAV.mat
  Jones matrix J extracted at the Catania receiver of the Tel Aviv–Catania link, with corresponding Unix time time.
• 2025-05-27T000000Z-2026-02-11T000000Z_ROM_GAR.mat
  Jones matrix J extracted at the Roma receiver of the Golfo Aranci–Roma link, with corresponding Unix time time.

Processing with Jones.m

When any of the above files are provided as input to Jones.m, the script returns the following output variables:

1. phi: the three components of the bare rotation vector.
2. phi1: the three components of the rotation vector compensated with respect to a reference rotation vector, computed by averaging over a time window specified (in hours) by the input parameter hours_averaging.
3. pdl: the polarization-dependent loss (PDL), in dB.
4. time: the Unix time vector (identical to the input time).
5. Twin: the averaging time window corresponding to hours_averaging, expressed in seconds.

The implementation follows the algorithm described in:
A. Mecozzi et al., “Geophysical sensing using Jones matrices extracted from submarine optical cable transceivers carrying live traffic,” Optica 12, 1712–1719 (2025), https://doi.org/10.1364/OPTICA.57288

Plot reproduction with Plot_and_stats.m

The outputs produced by Jones.m can be provided as input to Plot_and_stats.m to reproduce the figures in:
A. Mecozzi et al., “Earth-Scale Precursors of the Kamchatka Earthquake Revealed via Polarization Monitoring in Undersea Mediterranean Optical Fiber Links,” Optica, https://doi.org/10.1364/OPTICA.586317