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IJRSP Vol.41 [2012] >
IJRSP Vol.41(5) [October 2012] >
| Title: | A search for precursors of earthquakes from multi-station ULF observations and TEC measurements in India |
| Authors: | Chauhan, Vishal
Singh, O P
Pandey, Uma
Singh, Birbal
Arrora, B R
Rawat, Gautam
Pathan, B M
Sinha, A K
Sharma, A K
Patil, A V |
| Keywords: | Earthquake
ULF anomalies
Total electron content (TEC)
Ionospheric precursors |
| Issue Date: | Oct-2012 |
| Publisher: | NISCAIR-CSIR, India |
| PACS No.: | 91.30.pd; 94.20.dv; 94.20.Vv |
| Abstract: | Ground based
observations have been carried out for ultra low frequency (ULF) precursors of
earthquakes at four different stations in India, namely Agra (geographic lat
27°N, long 78°E), Guttu (lat 31.53°N, long 78.75°E), Shillong
(lat 25.92°N, long 91.88°E) and Kolhapur (lat 16.40°N, long 74.15°E) using
identical 3-component search coil magnetometers (f = 0.01-30 Hz) obtained from
Lviv Centre of Space Research, Ukraine. An offline analysis of the combined
data has been carried out in relation to a major earthquake of magnitude M=7.9
occurred in the neighbouring country China (lat 31°N, long 103.32°E, depth=19
km) under the National Program of Earthquakes Precursors (NPEP) launched in
India since May 2009. The results of the analysis show occurrence of amplitude
anomalies as precursors whose amplitudes decrease with distance. The precursor
periods range between 2 and 5 days and are large for the stations nearer to
epicenter. A graphical determination of location of the epicenter has been found
to be satisfactory with errors within 20.5%. Further, the total electron
content (TEC) data obtained from a dual frequency GPS receiver at Agra station and global
ionospheric maps (GIMs) of TEC corresponding to the Wenchuan earthquake have
also been analysed. The GIM TEC data have been analysed for five different
locations which lie between Agra
and the epicenter of the earthquake. The anomalies in TEC data are investigated
by using quartile based statistical process. It has been found that GPS and GIM
TEC data show anomalous depletions of
02 - 13 days before and anomalous enhancements of 03 - 10 days prior to the
occurrence of earthquake.
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| Page(s): | 543-556 |
| CC License: |  CC Attribution-Noncommercial-No Derivative Works 2.5 India |
| ISSN: | 0975-105X (Online); 0367-8393 (Print) |
| Source: | IJRSP Vol.41(5) [October 2012]
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