Sensing earthquakes in aerial single- and multi-core fiber optic networks

We report the first observation, to our knowledge, of an earthquake using state-of-polarization (SOP) monitoring on an aerial access network fiber cable containing both single- and multi-core fiber, enabling direct comparison under identical deployment. SOP variations correlate with seismic records and estimated P- and S-wave arrivals. Ground motion excites the pole-cable mechanical system, amplifying aerial cable displacement and producing frequency-selective SOP responses. The single-core fiber response is dominated by a primary structural resonance, whereas the multicore fiber exhibits additional low-frequency harmonics, likely due to higher sensitivity to bending-induced strain. These results demonstrate the potential of dense terrestrial fiber networks for low-cost polarization-based seismic monitoring.