A hot midmantle anomaly in the area of the Indian Ocean Geoid Low

作者：Reiss Anne Sophie; Thomas Christine; van Driel Jac; Heyn Bjorn

来源：Geophysical Research Letters, 2017, 44(13): 6702-6711.

DOI：10.1002/2017GL073440

We investigate the upper mantle seismic discontinuities at 410 and 660 km depth beneath the Indian Ocean Geoid Low (IOGL). To map the discontinuities' topography, we use differential travel times of PP and SS waves and their precursors. Our final data set consists of 37 events with M-w >= 5.8, which densely cover our investigation area, also with crossing ray paths. We use array methods to detect the low-amplitude precursor signals. The best quality data show a deepened 410 km discontinuity in the center of the IOGL as well as a mostly elevated 660 km discontinuity beneath the northern Indian Ocean, which we interpret as a hot anomaly currently residing in the mantle transition zone. We conclude that the largest negative geoid anomaly might be caused by a combined effect of hot material in the midmantle below the innermost IOGL and cold material below 660 km farther south.

• 出版日期2017-7-16