Seismic structure beneath the Lau Basin

The Lau Basin is a back-arc basin west of the Tonga subduction zone. It is an exemplary place for understanding fundamental processes of plate tectonic, such as subduction and back-arc spreading. My current researches include Rayleigh wave tomography and body wave attenuation tomography to image the mantle wedge.

Seismicity in northern Tibetan Plateau (INDEPTH IV)

A total of 400 regional earthquakes were located in northern Tibetan Plateau from data recorded by INDEPTH IV and PKU Eastern Kunlun arrays from May 2007 to June 2009. The distribution of these earthquakes is compatible with a continuously deforming Tibetan lithosphere. Most earthquakes occur at a depth range of 0‐15 km, but no event is deeper than 30 km. This observation strongly supports the existence of a hot and weak lower crust beneath the northern Tibet. The crustal seismogenic zone appears slightly thicker beneath the northern Tibet than in the southern plateau, possibly reflecting a difference in the rheological (dry vs. wet) structure of the crust. The absence of lower crustal and uppermost mantle earthquakes in northern Tibet is consistent with a localized asthenospheric upwelling under the Qiangtang and Songpan‐Ganze terranes. Finally, the lack of mantle earthquakes should be fully addressed in any models of subduction in northern Tibet.

Hainan mantle plume (Le-Muse)

The Hainan mantle plume has been proposed to explain the largest igneous province in Lei-Qiong region of southern China. We analyzed the data from regional broadband seismic stations using the receiver function method to study the seismic constrains of this plume. The shear wave velocity structures indicate high velocity anomalies in the upper crust and low velocity anomalies in the lower crust beneath the Leizhou Peninsula. This is the consequence of the eruption/intrusion of the mafic rocks in the upper crust and the partial melting in the lower crust. The migration images for the shallow structure of Lei-Qiong region show significant depression of the Moho discontinuity beneath the Leizhou Peninsula, where the Cenozoic basalt mostly outcropped, which is about 15 km deeper than that beneath the adjacent South China block and Hainan Island. This is consistent with the existence of the mantle plume as the up-welling mantle materials thickened the crust of Leizhou Peninsula. In addition, the migration imaging for the upper mantle shows a thinner transition zone (with the top boundary at 425 km depth and the bottom boundary at 650 km depth) beneath the Lei-Qiong region, which indicates the temperature is higher by ~ 200 ˚C than the surrounding mantle.


An interesting journey.