抄録
The equatorial electrojet through the southern peninsular India could be considered as one of the possible features responsible for non-uniformity in the magnetotelluric (MT) source field. The present study aims at examining the nature of such a non-uniformity in the equatorial region of India. A special field experiment was designed to facilitate simultaneous measurement of magnetic pulsation signals at pairs of mobile stations along a meridian from Kanyakumari to Hyderabad. The latitudinal variation in the strength of the MT source field shows an enhancement of signal amplitude by a factor of 2 to 3 right under the jet during 10-14Hr LT and a gradual decrease away from the dip equator. On the other hand, the signal strength is found to decrease towards the dip equator during 16-18Hrs LT. The results indicate that the source field effects may have to be taken into consideration when MT surveys for periods greater than 100sec., are carried out in the daytime in this region, particularly in the high resistive shield areas exposing the Archaean basement.
