利用远震接收函数研究黄海周边地区的地壳上地幔结构

Crust and upper-mantle structure beneath the region around the Yellow Sea from teleseismic receiver functions

利用宽频带流动台站(YSBSN)记录的远震波形数据和远震接收函数方法,反演了黄海东、西两侧地壳上地幔的S波速度结构.结果表明,莫霍面深度在30～38 km之间变化,位于中方一侧的JNN台下方地壳厚度最大,可以归因于华北板块和扬子板块的碰撞;韩方一侧的地壳厚度自北向南逐渐变厚,但仍然难以厘定朝鲜半岛南部潜在碰撞带的位置,这些问题的解决需要更大范围的流动台站观测.由于部分台站位于巨厚的沉积层和多孔的火山岩之上,与浅部构造的相关性使得接收函数表现出较大振幅的混响,从而影响了来自深部结构的转换震相.

Teleseismic events are used to obtain shear-wave velocity models beneath the stations of the Yellow Sea Broadband Seismic Network （YSBSN）. Some stations are located on top of either a thick sedimentary basin or highly porous volcanic rocks and receiver functions at these stations exhibit prominent high-amplitude and long-period reverberations which obscure the subtle phases associated with deeper structures. Due to the shallow subsurface effects in receiver functions, shear-wave velocity models beneath only 8 broadband seismic stations are successfully inverted. Depth to the crust-mantle transition （the Moho） varies from 30 to 38 km beneath YSBSN stations. The thickest crust is observed beneath the station JNN in China, which is attributed to the ancient collision boundary between the North China block and the South China block. Although general increase of the crustal thickness from north to south in Korea is observed with high confidence, it is not possible to delineate the location of potential collision boundary in the southern Korea peninsula, which would require wider coverage by broadband seismic instruments to resolve.