Ionospheric anomaly due to seismic activities – Part 2: Evidence from D-layer preparation and disappearance times

Chakrabarti, Sandip K.; Sasmal, Sudipta; Chakrabarti, S.

doi:10.5194/nhess-10-1751-2010

Cited by 64 publications

(34 citation statements)

References 11 publications

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“…The conclusion claimed by these authors is that ionospheric perturbations by means of the subionospheric VLF/LF data tend to definitely take place before an EQ when the EQ magnitude is greater than 5.5 and when the depth is shallow (d < 40 km). Also, a statistical study using an Indian transmitter has been done by Chakrabarti et al (2010), who have shown a possible correlation with EQs. Recently, two papers have been published about the rather complete statistical correlation between the ionospheric perturbation and EQs over nine years by using different VLF/LF propagation paths (Hayakawa et al, 2010a, b).…”

Section: Introductionmentioning

confidence: 99%

Ionospheric perturbations in possible association with the 2010 Haiti earthquake, as based on medium-distance subionospheric VLF propagation data

Hayakawa

Raulin

Kasahara

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. Ionospheric perturbations in possible associationwith the 2010 Haiti earthquake occurred on 12 January 2010 (with a magnitude of 7.0 and depth of 10 km) are investigated on the basis of subionospheric propagation data from the NAA transmitter on the east coast of the USA to a VLF receiving station in Peru. The local nighttime VLF amplitude data are extensively investigated during the period from the beginning of October 2009 to the end of March 2010, in which the trend (nighttime average amplitude), dispersion and nighttime fluctuation are analysed. It is found that a clear precursory ionosphere perturbation is detected just around New Years day of 2010, about 12 days before the main shock, which is characterised by the simultaneous decrease in the trend and the increases in dispersion and nighttime fluctuation. An additional finding might be the presence of the effect of the Earth's tide one and two months before the main shock, which can only be seen for a huge EQ.

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Section: Introductionmentioning

confidence: 99%

Ionospheric perturbations in possible association with the 2010 Haiti earthquake, as based on medium-distance subionospheric VLF propagation data

Hayakawa

Raulin

Kasahara

et al. 2011

Nat. Hazards Earth Syst. Sci.

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“…Various causes of disturbances have been identified mainly from space and tropospheric phenomena. Therefore VLF signals contain information about an evolution of the lower ionosphere (e.g., D-layer formation and disappearance time) (Chakrabarti et al, 2010), space weather effects such as geomagnetic storms (Kikuchi and Evans, 1983), effects of solar flares and solar energetic particles events (Mitra, 1974;Thomson and Clilverd, 2001;Todoroki et al, 2007), lightning-induced energetic particle precipitations and direct heating due to intensive lightning discharges and Transient Luminous Events (TLEs) (Inan et al, 1985(Inan et al, , 1988Hobara et al, 2001) and even effects of strong gamma ray bursts far away beyond the solar system (Tanaka et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Sub-ionospheric VLF signal anomaly due to geomagnetic storms: a statistical study

et al. 2015

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Abstract. We investigate quantitatively the effect of geomagnetic storms on the sub-ionospheric VLF/LF (Very Low Frequency/Low Frequency) propagations for different latitudes based on 2-year nighttime data from Japanese VLF/LF observation network. Three statistical parameters such as average signal amplitude, variability of the signal amplitude, and nighttime fluctuation were calculated daily for 2 years for 16-21 independent VLF/LF transmitter-receiver propagation paths consisting of three transmitters and seven receiving stations. These propagation paths are suitable to simultaneously study high-latitude, low-mid-latitude and midlatitude D/E-region ionospheric properties. We found that these three statistical parameters indicate significant anomalies exceeding at least 2 times of their standard deviation from the mean value during the geomagnetic storm time period in the high-latitude paths with an occurrence rate of anomaly between 40 and 50 % presumably due to the auroral energetic electron precipitation. The mid-latitude and lowmid-latitude paths have a smaller influence from the geomagnetic activity because of a lower occurrence rate of anomalies even during the geomagnetically active time period (from 20 to 30 %). The anomalies except geomagnetic storm periods may be caused by atmospheric and/or lithospheric origins. The statistical occurrence rates of ionospheric anomalies for different latitudinal paths during geomagnetic storm and non-storm time periods are basic and important information not only to identify the space weather effects toward the lower ionosphere depending on the latitudes but also to separate various external physical causes of lower ionospheric disturbances.

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“…In Chakrabarti et al (2007) a preliminary discussion was made to show that these quantities may also be used to study ionospheric anomalies. In our next paper, (Chakrabarti, Sasmal and Chakrabarti, 2009) we will show the correlations of DLPT and DLDT with the seismic activities.…”

Section: Discussionmentioning

confidence: 97%

Ionosperic anomaly due to seismic activities – Part 1: Calibration of the VLF signal of VTX 18.2 KHz station from Kolkata and deviation during seismic events

Sasmal

Chakrabarti

2009

Nat. Hazards Earth Syst. Sci.

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Abstract. VLF signals are long thought to give away important information about the lithosphere-ionosphere coupling. In order to establish co-relations, if any, between the ionospheric activities and the earthquakes, we need to understand what the reference signals are, throughout the year. The best opportunity to do this is during the period of solar minimum where the number of flares and sunspots are negligible and the data would be primarily affected by the sun and variation would be due to normal sunset and sunrise effects. In this paper, we present the result of the sunrise and sunset terminators as a function of the day of the year for a period of four years, viz, 2005-2008 when the solar activity was very low. The terminators are for the 18.2 KHz VTX signal of the Indian Navy as observed from Indian Centre for Space Physics receiving station located in Kolkata. A total of 624 days of data have been used to obtain the mean plot. Any deviation of observations from this so-called the standardized calibration curve would point to influences by terrestrial (such as earthquakes) and extra-terrestrial events (such as solar activities). We present examples of deviations which occur in a period of 16 months and show that the correlation with seismic events is significant and typically the highest deviation takes place up to a couple of days prior to the seismic event. Simultaneous observations of such deviations from more than one station could improve the predictability of earthquakes.

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Ionospheric anomaly due to seismic activities – Part 2: Evidence from D-layer preparation and disappearance times

Cited by 64 publications

References 11 publications

Ionospheric perturbations in possible association with the 2010 Haiti earthquake, as based on medium-distance subionospheric VLF propagation data

Ionospheric perturbations in possible association with the 2010 Haiti earthquake, as based on medium-distance subionospheric VLF propagation data

Sub-ionospheric VLF signal anomaly due to geomagnetic storms: a statistical study

Ionosperic anomaly due to seismic activities – Part 1: Calibration of the VLF signal of VTX 18.2 KHz station from Kolkata and deviation during seismic events

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