| Abstract Submission No. | ABS-3.1-0099 |
| Title of Abstract | Estimation of Earthquake Magnitudes from Ionospheric Perturbations Using Empirical method |
| Authors | SUBRATA KUNDU*, Mala S. Bagiya, A. P .Dimri |
| Organisation | INDIAN INSTITUTE OF GEOMAGNETISM |
| Address | INDIAN INSTITUTE OF GEOMAGNETISM NAVI MUMBAI, Maharashtra, India Pincode: 410218 E-mail: mcqmld@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | Co-seismic ionospheric perturbations (CIP), observed near the earthquake epicenter, provide insights into the underlying earthquake source processes. The amplitude of these near-field CIPs (within ~500-600 km of the epicenter) is mainly controlled by seismic parameters, such as earthquake magnitude and depth. Nevertheless, non-seismic factors including the geomagnetic field, background ionospheric electron density, and satellite-receiver geometry also significantly influence the manifestation of CIP at ionospheric altitudes. Using GNSS-derived Total Electron Content (TEC) data, we identified the CIP for 75 global earthquakes (Mw >6.4, depth < 110 km) that occurred between 2000 and 2024. The present study aims to systematically investigate the individual and combined effects of both seismic and non-seismic parameters in controlling CIP amplitudes. To achieve this, we developed an empirical relationship that combines both seismic and non-seismic parameters to reconstruct CIP amplitudes using an iterative least-squares curve-fitting approach. This formulation allows for a quantitative assessment of the relative contributions of each factor to CIP generation. Our analysis reveals that earthquake magnitude, satellite geometry, background ionospheric electron density, and geomagnetic field exert a positive influence on CIP amplitudes, enhancing their strength, whereas focal depth and ionospheric pierce point (IPP) distance act as limiting factors, reducing the observed perturbation. Leveraging this relationship, we demonstrate the capability to estimate earthquake magnitude (Mw) directly from observed CIP amplitudes. The method provides magnitude estimates with an uncertainty of 0.3, reflecting robust predictive accuracy. Validation against five independent earthquakes, spanning different magnitudes and tectonic settings, confirmed that the estimates consistently fell within this uncertainty range. Overall, the study highlights the potential of ionospheric measurements for earthquake monitoring. The ability to estimate earthquake magnitudes from ionospheric data represents a step forward in ionospheric seismology, opening new opportunities for integrating space-based observations into earthquake science. |
| Keywords | Empirical model, reconstructed CIP, earthquake, Ionospheric perturbation, Magnitude estimation, GNSS-TEC |