Abstract:This paper is focused on the short-term variations of near surface temperature (T) obtained over a period of one week prior to the earthquake occurrence (EQ). We found a systematic temperature increase in almost the entire examined area (i.e. 8˚-30˚E and 35˚-53˚N), reaching a maximum in Aegean-Balkans-Pannonia basin region. Total of 1039 EQs have been analysed, what ensures statistical significance of our results. Comparison with the spatial distribution of geomagnetic variability reveals a striking similarity… Show more
“…Moreover, location and local solar time of the satellite pass also play a vital role in the lower ionospheric dynamics. The observed variability of mesospheric ozone anomaly decreasing (increasing) with increasing (decreasing) altitudes (above/below 70 km) signifying the role of ionospheric electrodynamics along with ion chemistry through atomic oxygen as we go to higher altitude regions in governing the D-region dynamics 21 – 23 , 33 . Figure 4 Temporal variation of SABER mesospheric ozone anomaly along with mean VLF amplitude (spline interpolated solid black line) and magnitude of EQs (black circles) for three different regions ( a ) 60 km, ( b ) 65 km and ( c ) 70 km, respectively during April 20 – May 13 2015.…”
Section: Introductionmentioning
confidence: 97%
“…In tandem with observed VLF anomaly 13 during Gorkha Nepal EQ, several simultaneous ionospheric parameters are scrutinized and found that VLF anomaly has a close relation with ozone concentration variation at mesospheric altitudes. Although few studies in the recent past focused on the enhancement of ozone concentration during earthquakes over different parts of the globe by utilizing satellite data along with ground-based observations to better understand the atmospheric variations (columnar ozone, surface temperature, electric field variations) prior to EQs in order to have clarity on the parameters (time, epicentre and magnitude) of the forthcoming earthquakes 21 – 23 .However, this is the first report to establish a strong relationship between pre-seismic VLF signal amplitude/TT and mesospheric ozone anomalies prior to any major earthquakes over Himalayan region reported till date. Rigorous and detailed analysis is performed with VLF NWC (19.8 kHz) transmitter data recorded at Allahabad (25.41° N, 81.93° E) for two major EQs (EQ1 and EQ2) which occurred within a short span of 20 days apart from the multiple aftershocks subsequent to EQ1 event.…”
The subject of pre-earthquake ionospheric signatures has always been contentious and debatable. Some of the previous reports have documented unforeseen and unusual variations in some of the atmospheric and ionospheric parameters well before an earthquake. Here, we analyze the ionospheric response from the Indian Subcontinent to Nepal Gorkha Earthquakes occurred between April and May 2015, which were the most powerful and disastrous natural calamities in past ~80 years over the Himalayan region left ~9000 causalities and more than ~20000 people injured with the property damage of the order of several billion dollars. In view of severe earthquakes occurrences, their prior information on the shorter time scales are warranted for mitigation of associated disasters. Here, we report for the first time, a case which shows a strong link in anomalous variations between VLF sub-ionospheric signal and mesospheric ozone prior to both April 25, 2015 (Mw = 7.8) earthquake and its biggest aftershock on May 12, 2015 (Mw = 7.3). Observations show an unusual variation in VLF signals amplitude /shift in terminator time (TT) strongly linked with positive (negative) mesospheric ozone anomaly in D-region altitudes prior to the Gorkha Nepal earthquakes. It is surmised that simultaneous continuous observations of both VLF waves and mesospheric ozone can be considered as an important tool to identify the prior earthquake signatures in the vicinity of the extremely earthquake-prone zone such as Himalayan region. In this context, the current report opens up a new dimension in lithosphere-atmosphere-ionosphere coupling during the earthquake preparation processes itself.
“…Moreover, location and local solar time of the satellite pass also play a vital role in the lower ionospheric dynamics. The observed variability of mesospheric ozone anomaly decreasing (increasing) with increasing (decreasing) altitudes (above/below 70 km) signifying the role of ionospheric electrodynamics along with ion chemistry through atomic oxygen as we go to higher altitude regions in governing the D-region dynamics 21 – 23 , 33 . Figure 4 Temporal variation of SABER mesospheric ozone anomaly along with mean VLF amplitude (spline interpolated solid black line) and magnitude of EQs (black circles) for three different regions ( a ) 60 km, ( b ) 65 km and ( c ) 70 km, respectively during April 20 – May 13 2015.…”
Section: Introductionmentioning
confidence: 97%
“…In tandem with observed VLF anomaly 13 during Gorkha Nepal EQ, several simultaneous ionospheric parameters are scrutinized and found that VLF anomaly has a close relation with ozone concentration variation at mesospheric altitudes. Although few studies in the recent past focused on the enhancement of ozone concentration during earthquakes over different parts of the globe by utilizing satellite data along with ground-based observations to better understand the atmospheric variations (columnar ozone, surface temperature, electric field variations) prior to EQs in order to have clarity on the parameters (time, epicentre and magnitude) of the forthcoming earthquakes 21 – 23 .However, this is the first report to establish a strong relationship between pre-seismic VLF signal amplitude/TT and mesospheric ozone anomalies prior to any major earthquakes over Himalayan region reported till date. Rigorous and detailed analysis is performed with VLF NWC (19.8 kHz) transmitter data recorded at Allahabad (25.41° N, 81.93° E) for two major EQs (EQ1 and EQ2) which occurred within a short span of 20 days apart from the multiple aftershocks subsequent to EQ1 event.…”
The subject of pre-earthquake ionospheric signatures has always been contentious and debatable. Some of the previous reports have documented unforeseen and unusual variations in some of the atmospheric and ionospheric parameters well before an earthquake. Here, we analyze the ionospheric response from the Indian Subcontinent to Nepal Gorkha Earthquakes occurred between April and May 2015, which were the most powerful and disastrous natural calamities in past ~80 years over the Himalayan region left ~9000 causalities and more than ~20000 people injured with the property damage of the order of several billion dollars. In view of severe earthquakes occurrences, their prior information on the shorter time scales are warranted for mitigation of associated disasters. Here, we report for the first time, a case which shows a strong link in anomalous variations between VLF sub-ionospheric signal and mesospheric ozone prior to both April 25, 2015 (Mw = 7.8) earthquake and its biggest aftershock on May 12, 2015 (Mw = 7.3). Observations show an unusual variation in VLF signals amplitude /shift in terminator time (TT) strongly linked with positive (negative) mesospheric ozone anomaly in D-region altitudes prior to the Gorkha Nepal earthquakes. It is surmised that simultaneous continuous observations of both VLF waves and mesospheric ozone can be considered as an important tool to identify the prior earthquake signatures in the vicinity of the extremely earthquake-prone zone such as Himalayan region. In this context, the current report opens up a new dimension in lithosphere-atmosphere-ionosphere coupling during the earthquake preparation processes itself.
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