TRAVEL-TIME RESIDUALS OF TELESEISMIC P-WAVES AT THE RODRIGUEZ TRIPLE JUNCTION IN THE INDIAN-OCEAN USING OCEAN-BOTTOM SEISMOMETERS

We conducted three weeks of seismic observations at the Rodriguez Trip le Junction (RTJ) in the Indian Ocean using 18 ocean-bottom seismomete rs over an area of 90km x 90km. We identified six teleseismic events a nd obtained significant anomalies in the relative travel-time residual s of the teleseismic P-waves. The residuals are positive at the RTJ, t he northern part of the Southeast Indian Ridge (SEIR), and the eastern side of the Central Indian Ridge (CIR), and are negative at and aroun d the Southwest Indian Ridge (SWIR). It is suggested that there is a r elatively hotter mantle under the triple junction and the northern par t of the SEIR segment, along-axis variations in mantle temperature alo ng the SEIR segment, and cooler mantle under the SWIR segment. The CIR segment has an asymmetrical distribution of relative residuals.