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    Seismo Ionospheric Anomalies around and over the Epicenters of Pakistan Earthquakes
    (2023-03-01)
    Shah, Munawar
    ;
    Shahzad, Rasim
    ;
    Ehsan, Muhsan
    ;
    Ghaffar, Bushra
    ;
    Ullah, Irfan
    Global Navigation Satellite System (GNSS)-based ionospheric anomalies are nowadays used to identify a possible earthquake (EQ) precursor and hence a new research topic in seismic studies. The current study also aims to provide an investigation of ionospheric anomalies associated to EQs. In order to study possible pre-and post-seismic perturbations during the preparation phase of large-magnitude EQs, statistical and machine learning algorithms are applied to Total Electron Content (TEC) from the Global Positioning System (GPS) and Global Ionosphere Maps (GIMs). We observed TEC perturbation from the Sukkur (27.8° N, 68.9° E) GNSS station near the epicenter of Mw 5.4 Mirpur EQ within 5–10 days before the main shock day by implementing machine learning and statistical analysis. However, no TEC anomaly occurred in GIM-TEC over the Mirpur EQ epicenter. Furthermore, machine learning and statistical techniques are also implemented on GIM TEC data before and after the M<inf>w</inf> 7.7 Awaran, where TEC anomalies can be clearly seen within 5–10 days before the seismic day and the subsequent rise in TEC during the 2 days after the main shock. These variations are also evident in GIM maps over the Awaran EQ epicenter. The findings point towards a large emission of EQ energy before and after the main shock during quiet storm days, which aid in the development of lithosphere ionosphere coupling. However, the entire analysis can be expanded to more satellite and ground-based measurements in Pakistan and other countries to reveal the pattern of air ionization from the epicenter through the atmosphere to the ionosphere.
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    Possible Thermal Anomalies Associated with Global Terrestrial Earthquakes during 2000-2019 Based on MODIS-LST
    (2022-01-01)
    Shah, Munawar
    ;
    Ehsan, Muhsan
    ;
    Abbas, Ayesha
    ;
    Ahmed, Arslan
    ;
    Jamjareegulgarn, Punyawi
    The recent advances in satellite-based earthquakes (EQs) precursors provide an opportunity to correlate the seismic variation on lithosphere with atmosphere during the EQ preparation period through a rigorous atmospheric monitoring system. In the present study, seismic-induced thermal anomalies from cloud-free satellite thermal images of Moderate Resolution Imaging Spectroradiometer-Land Surface Temperature (MODIS-LST) are analyzed within a time interval of three months (precedent two months and succeeding one month to each EQ day) of 13 $\text{M}_{w} \ge6.0$ terrestrial EQs during 2000-2019. All these EQs occur in low vegetation and no snow cover regions except $\text{M}_{w}~6.7$ , Siberia Russia event. Remote sensing data show evidence of significant perturbation with reference to confidence bounds in LST within 5-20 time window upon the antecedent and the descendant of EQ day. The studied thermal anomalies are obtained from LST values over the epicenter region. This work endorses the performance of MODIS-LST for detecting EQ-induced thermal anomalies in terrestrial regions with no vegetation and snow cover and also assisting to the development of lithosphere-atmosphere hypothesis over the epicenter region.
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    Ionospheric-Thermospheric Responses in South America to the August 2018 Geomagnetic Storm Based on Multiple Observations
    (2022-01-01)
    Shah, Munawar
    ;
    Abbas, Ayesha
    ;
    Ehsan, Muhsan
    ;
    Aiber, Andres Calabia
    ;
    Adhikari, Binod
    The ionospheric storm time responses during August 2018 are investigated over South American region using multiple observables, for example, Global Navigation Satellite System (GNSS) derived vertical total electron content (VTEC) from International GNSS Service, magnetic field data, geomagnetic indices, global ionospheric maps, thermospheric mass density (TMD), and [O/N2] ratio measurement. Strong-ionospheric and upper-atmospheric disturbances affected the ionospheric variables with long duration during the storm recovery phase and following after. First, daytime VTEC (9:00-20:00 UT) presented variations of >15 TECU during days 25 to 30 of August 2018 in low and middle latitudes of South America, this after sudden storm commencement (SSC). Furthermore, nighttime (21:00-24:00 and 00:00-05:00 UT) VTEC presented low values (5<TECU<7) in mid-latitude region after SSC event during the main phase, followed by high values (>8 TECU) in the recovery phase. Second, the ionospheric values during the storm main phase and following after, at low-and mid-latitudes, caused the equatorial ionization anomaly to expand due to prompt penetration electric field. Furthermore, VTEC enhancements are likely to occur few hours after the SSC of 25 August 2018, while enhancements of TMD and [O/N2] ratio started to appear later on 26 and 27 of August 2018.
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    Possible atmosphere and ionospheric anomalies of the 2019 Pakistan earthquake using statistical and machine learning procedures on MODIS LST, GPS TEC, and GIM TEC
    (2021-01-01)
    Hafeez, Amna
    ;
    Shah, Munawar
    ;
    Naqvi, Najam Abbas
    ;
    Ehsan, Muhsan
    ;
    Jamjareegulgarn, Punyawi
    Identifying atmospheric and ionospheric anomalies based on remote sensing satellites has contributed highly to develop the hypothesis of lithosphere-atmosphere-ionosphere coupling over the earthquake (EQ) epicenter during the seismic preparation period. This article has investigated the variations of potential EQ precursor in daytime and nighttime land surface temperature (LST) before and after the 2019 Pakistan EQ from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite. The nighttime LST values of MODIS exhibit temporal anomalies during nighttime period within a time window of five days before and after the main shock day. Furthermore, the LST values predicted by artificial neural network (ANN) validate the significant enhancement in nighttime time series of MODIS. The nighttime LST anomalies obtained from the observation and ANN prediction are more than 20% and 7% of normal distribution beyond the confidence bounds, respectively, within five days after the main shock. Likewise, the ionospheric anomaly from daily total electron content (TEC) values at Sukkur Global Positioning System (GPS) station confirms the EQ associated ionospheric perturbations on the day after the main shock. The Global Ionospheric Maps (GIMs) also show the TEC anomalies during 1000–1400 LT on September 25, 2019.