Mantle transition zone structure around Hainan by receiver function analysis

We have obtained the upper mantle 410 km discontinuity and 660-km discontinuity structure and transition zone thickness around Hainan by using receiver function method. The data used in this study was teleseismic waveforms recorded by 88 seismic stations of Hainan, Guangdong and Guangxi Regional Seismic Network and National Seismic Network during August, 2007 to March, 2010. Our results show that the structure of 410 km discontinuity is complex in this region, it is depressed to 447 km locally. The 660 km discontinuity is simple relatively, with the depth around 670 km. Transition zone is thinned anomalously by 25 +/- 5km within an area approximately 200km in diameter centered northeast of Hainan island, this anomaly is consistent with an excess temperature of similar to 180 degrees C. The locally thinned transition zone implies that Hainan plume originates from lower mantle.