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| Titel |
A study of the behavior of the terminator time shifts using multiple VLF propagation paths during the Pakistan earthquake (M = 7.2) of 18 January 2011 |
| VerfasserIn |
S. Ray, S. K. Chakrabarti |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 6 ; Nr. 13, no. 6 (2013-06-18), S.1501-1506 |
| Datensatznummer |
250018497
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| Publikation (Nr.) |
 copernicus.org/nhess-13-1501-2013.pdf |
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| Zusammenfassung |
| On 18 January 2011, at 20:23 UTC, an earthquake of magnitude 7.2 occurred in
southwestern Pakistan (latitude 28°44' N, longitude
63°56' E) at a depth of 68 km. We present the results of the
analysis of very low frequency (VLF) radio signals, received at three
stations located in India. We analyze the VLF signals around this earthquake
day and look for possible precursory effects of this earthquake. For our
analysis, we use four different VLF propagation paths. These propagation
paths are DHO–IERC (Sitapur), VTX–Pune, VTX–ICSP (Indian Centre for Space
Physics, Kolkata) and NWC–IERC. We observed significant shifts of the
"sunrise terminator time" (SRT) for DHO–IERC and VTX–Pune paths. For
DHO–IERC path, the SRT of the VLF signals shifted towards nighttime three
days before the earthquake day, and in the case of VTX–Pune path it shifted
towards nighttime just one day before the earthquake day. For VTX–Kolkata
path, the shift of SRT is four days before the earthquake day, but here the
shift is not so strong, somewhere between 2σ and 3σ lines. For
the other two paths, namely, DHO–IERC and VTX–Pune, the terminator time
shifts crossed the 3σ line. We found no significant shifts of SRT for
NWC–IERC propagation path. Higher deviation in the VTX–Pune path as
compared to VTX–ICSP path could be due to the proximity of the former to the
epicenter. Similarly, DHO–IERC path is over the epicenter while NWC–IERC
path is totally away from the epicenter. This could be the reason why the
effect in DHO–IERC path is stronger than that in NWC–IERC path. |
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