Simulation Framework for Earthquake Early Warning Using Optical Fiber Networks

This work presents a simulation framework for enhancing Earthquake Early Warning Systems (EEWS) through the use of optical fiber networks as seismic sensors. The primary objective is to improve the detection and characterization of seismic events by leveraging changes in the state of polarization (SOP) of light signals propagating through optical fibers affected by seismic-induced strain. This research aims to provide timely alerts that could help safeguard cities before the earthquake's impact by developing a more accurate and comprehensive model of fiber optic behavior during seismic events. The proposed framework integrates a new modeling approach that combines realistic strain propagation along fiber lines with a detailed waveplate model to account for the effects of birefringence and polarization changes. The fiber optic network is represented as a series of nodes and lines, where each line is segmented into smaller units experiencing unique strain evolution due to seismic waves. The strain evolution within each segment is calculated to determine the SOP evolution at the end of each line. A key assumption in the model is that seismic waves induce a uniform strain effect across each segment of the fiber. This assumption simplifies the complex interactions of seismic waves with the optical fibers, allowing a more manageable analysis of SOP changes. The segment-based strain data are then used to compute the accumulation of polarization changes along the entire fiber length. The time base is unified to synchronize the detection and propagation effects of the earthquake across different parts of the network, allowing the system to measure the impact of the seismic wave as it reaches different segments and determine the SOP accordingly. The simulation framework is designed to assess the feasibility of using optical fiber networks for real-time monitoring and early warning of seismic events. By analysing the polarization changes observed at both the beginning and the end of each fiber line, the system aims to provide critical seconds of warning that are essential for implementing safety measures. The results demonstrate that optical fiber networks can effectively detect and characterize seismic events, providing a new avenue for the deployment of rapid and efficient responses to ensure public safety in the event of an earthquake. This research contributes to the field of earthquake early warning systems by offering a detailed understanding of how seismic waves interact with optical fibers. The developed model and simulation framework enhance the detection capabilities of optical fiber-based EEWS, paving the way for further advancements in the use of fiber optics for seismic monitoring and public safety.