Investigation of the inferred continental flexure in the west of India and the non-rigidity of the oceanic part of the Indian plate by episodic GPS Campaigns at Lakshadweep Islands along the Chagos-Laccadive ridge

Three Episodic GPS campaigns were carried out at Lakshadweep islands with the objectives of reaffirming the inferred continental flexure in the south-west of India, refining the already estimated strain accumulation in the south of Indian peninsula, and investigating the rigidity of larger oceanic part of the Indian plate. The islands Kavaratti, the northern most island Chetlat and the southern most island Minicoy were chosen. With the new state-of-the-art GNSS receivers, which could track 30 GPS and 11 GLONASS Satellites with 5deg elevation mask, GNSS measurements were carried out during 2007 simultaneously in all these islands. They were reoccupied during 2008 and 2009.The acquired data was processed using Bernese 5.0 in the latest ITRF 2005 reference Frame. The site coordinates of Kavaratti, Chetlat and Minicoy and also the baseline lengths between Hyderabad and these three sites were estimated in the Global Network Solution. The estimated baseline length between Hyderabad and Kavaratti is 991, 303.3067 ± 0.0082m. The estimated baseline length between Hyderabad and Chetlat is 892, 216.5594 ± 0.0040m. The estimated baseline length between Hyderabad and Minicoy is 1171, 071.8777 ± 0.0065m. The estimated accuracy of the baseline length is in the range of 4 to 8 mm, which shows the quality of data processing. These studies across a 1,200-km-long "strain gauge" that is optimally oriented almost parallel to the compression seen on the land would enable the understanding whether this is due to the Himalayan collision, or the extension of the Capricorn-India diffuse boundary that could have extended this far north. Key words: GNSS, Episodic GPS Campaign, Strain gauge, Plate rigidity