[SIT25-P14] Whole-mantle P-wave tomography beneath East Asia
Keywords:Seismic tomography, East Asia, Hainan plume
We use a large number of P-wave arrival time data of earthquakes selected from the ISC-EHB catalog and Annual Bulletin of Chinese Earthquakes. The events are relocated using depth phase data. To select a best set of earthquakes, we divided the crust and mantle into small cubic blocks and only selected an event in each block that had the maximum number of arrival-time data and the smallest error in the hypocentral location. The events are selected so that they have a uniform distribution in the study region.
We use the multiscale global tomography method (Zhao et al., 2013, 2017), which can prevent the over-dense grid nodes arranged at higher latitudes. A denser 3-D grid is arranged in East Asia, whereas a coarser 3-D grid is arranged in the surrounding whole globe.
Our new tomographic model shows the following features.
(1) Low-velocity anomalies are generally revealed in the whole mantle under the Hainan region, which may reflect the whole-mantle Hainan plume.
(2) Very heterogeneous structures are revealed under the Tibetan region, which may reflect the complex subduction of the Indian plate beneath the Eurasian plate.
(3) Slab tear is revealed under the marginal seas, which is consistent with the recent result obtained by Ma et al. (2019).
Ma, J., Y. Tian, D. Zhao, C. Liu, T. Liu (2019). Mantle dynamics of Western Pacific and East Asia: New insights from P-wave anisotropic tomography. Geochem. Geophys. Geosyst. 20, 3628-3658.
Zhao, D., S. Yu, E. Ohtani (2011). East Asia: Seismotectonics, magmatism and mantle dynamics. J. Asian Earth Sci. 40, 689-709.
Zhao, D., Y. Yamamoto, T. Yanada (2013). Global mantle heterogeneity and its influence on teleseismic regional tomography. Gondwana Res. 23, 595-616.
Zhao, D., M. Fujisawa, G. Toyokuni (2017). Tomography of the subducting Pacific slab and the 2015 Bonin deepest earthquake (Mw 7.9). Scientific Reports 7, 44487, doi:10.1038/srep44487.