Potential Utilization of Multi-Parametric Earthquake Precursory Signatures in Support of LAIC Mechanism: A case study on Turkey- Syria Earthquake (6th Feb, 2023).

Disastrous earthquakes are a permanent threat to every second resident of our planet causing a massive loss of lives and property. Understanding the nature of earthquake precursory signatures and related hazard mitigation has immense potential for scientific advancement as well as for societal benefits. To study these multidisciplinary and complicated precursory signatures, several models have been proposed in favor of the Lithosphere- Atmosphere- Ionosphere- Coupling (LAIC) mechanism by earlier workers. The major objective of this study is to investigate the short-term perturbations in land surface temperature (LST), atmospheric air temperature (AT), atmospheric relative humidity (ARH), and in ionospheric vTEC prior to the destructive shallow sheeted Turkey-Syria earthquake (Mw 7.8, Depth 10 Km, Intensity IX) on 6^th February 2023 and its major aftershocks (Mw 7.5, 6.8, 6, 6). Earthquakes of such large magnitude causes synchronization changes, not only in the atmospheric parameters but also in the ionospheric TEC. The GPS and GNSS (IGS) derived ionospheric TEC data are now being used extensively to investigate seismo-ionospheric perturbations over and near the epicentral regions of earthquakes over the last two decades. To identify the perturbation in the LST and atmospheric parameters (AT and RH), we have studied the spatio-temporal variation of MODIS (Terra) derived LST data and MERRA 2 (NASA) derived atmospheric temperature and relative humidity at 2 meter height. The Terra-MODIS derived LST differential time series reveals a prominent increase ~ 6-16 ⁰C from 18^th to 26^th Jan, 2023 around the epicentral region. Moreover, the hourly varying atmospheric parameters (AT, RH) have shown significant and synchronous deviations from 18^th Jan to 26^th Jan. The highest positive (+ve) deviation in the AT is found to be 10.33 ⁰C and the lowest negative (-ve) anomaly in the RH is found to be 45.67% on 19^th Jan. The observed atmospheric anomalies are identified with respect to the constructed bounds using past 5 years hourly data (m ± 2σ). The temporal variation of ionospheric vTEC of the nearest grid point, derived from both GNSS (IGS) and GPS receivers shows a series of prominent –ve anomalies from 25^th Jan to 1^st Feb about 5-12 days prior to the main shock. After ruling out possible contributions due to the solar terrestrial environment with respect to F10.7 Scale and Ap index, it is found that the evolved TEC anomaly is seismogenic in origin. In order to visualize the TEC anomaly in spatio-temporal domain, we have plotted 2D latitude-longitude time (LLT) maps of different epochs during those anomalous days (Max anomaly~ -15 TECu on 28th Jan at UTC 11th and 12th hour). Considering the nearest plate boundary, spatial extent of TEC conjugates and TEC gradient we have determined the probable epicenter which showed very promising correlation in comparison to actual epicenter. This multi parametric spatio-temporal analysis of the pre-seismic signature will produce some beneficial insight to understand the LAIC mechanism in detail and somehow be able to save so many lives.