• Abraham A

The interplanetary magnetic field (IMF) contains temporal variations. Solar wind-magnetosphere coupling mediates these disturbances to the geomagnetic field. The vertical variance (VV) index is an effective tool in analyzing this coupling. Analysis shows that the extent of effective coupling is characteristic of each station and varies with time. Since solar wind-magnetosphere coupling is a global phenomenon, this variation is strongly correlated between stations. However, this correlation is disturbed by local events whose signatures are present in the geomagnetic field. This paper examines the role of earthquakes in the loss of solar wind-magnetosphere coupling correlation between selected geomagnetic observatories, viz., Alibag, Huancayo, Phu Thuy, Qsaybeh. The inter-station geomagnetic field-IMF vertical variance index ratio (GM-IMF VVIR) correlations of the selected station pairs are analyzed. Anomalies in the form of dips are observed in the inter-station correlations prior to the occurrence of earthquakes. The findings made here have been substantiated by the fact that the anomaly is absent during earthquake (EQ) free intervals. Analysis for the months of April 2004 is presented in this paper. Even as EQs may not be the single source of local effects on the inter-station correlations, observations presented here suggest that EQs have a part in the IMF-geomagnetic field coupling anomaly.

Earthquakes, Anomaly, Precursors

"IMF- Geomagnetic Field Coupling and Earthquakes", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.5, Issue 4, page no.51-54, April-2018, Available :http://www.jetir.org/papers/JETIR1804471.pdf

"IMF- Geomagnetic Field Coupling and Earthquakes", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.5, Issue 4, page no. pp51-54, April-2018, Available at : http://www.jetir.org/papers/JETIR1804471.pdf