Receiver function imaging of high-resolution seismic discontinuity structure in the crust and the mantle beneath the Japan Islands

利用日本列岛高密度短、宽带地震台（J台阵、Hi-net和F-net）的接收函数（RF）进行偏移，研究了日本列岛地壳和上地幔的地震速度不连续结构，对于地壳和上地幔结构，我们使用短周期RF。在日本西南部的中国和近畿地区，我们可以识别出正的RF振幅对应的P-S转换相位之间的速度不连续的上，下地壳和莫霍面。对应于俯冲菲律宾海（PHS）板块上方的海洋莫霍面的正RF振幅被清楚地追踪到100公里的深度。与深震活动的对比表明，在40- 60 km深度范围内，洋壳地震和板片地震都有发生，而PHS地震的震源深度较深，在日本东北部，我们可以成功地捕捉到板片层状构造，并在地震活动中发现了一些异常。 ...更多信息 当然。也就是说，我们可以清楚地看到俯冲太平洋板块的顶部，海洋莫霍面，以及令人惊讶的板块底部。反射率表明双地震带中存在与下地震带相对应的地震不连续结构。这些新发现对俯冲板片及其周围的热结构和物质组成有很强的约束作用。410 km的不连续面似乎是平坦的，除了板片内部，410在局部抬高了30 km。660逐渐向西倾斜，这种凹陷是由寒冷的停滞板造成的。此外，对410 km和660 km处的RF振幅的频率依赖性的分析表明，日本列岛和朝鲜半岛的RF具有不同的频率特征，这表明日本列岛和朝鲜半岛上地幔中存在不同的水。少

We migrate the receiver functions(RFs) observed at high-density short and broad-band seismic stations (J-array, Hi-net and F-net) to investigate the seismic velocity discontinuity structure in the crust and the upper mantle beneath the Japan Islands.For the crust and the uppermost mantle structure, we use short-period RFs. In the Chugoku and Kinki region in southwest Japan where the stations are closely installed, we can recognize positive RF amplitudes corresponding to P-S converted phases at the velocity discontinuity between the upper and lower crust and the Moho discontinuity. The positive RF amplitudes corresponding to the oceanic Moho above the subducting Philippine Sea(PHS) plate are clearly traced down to a depth of 100 km. Comparison of the RFs with deep seismicity shows that the earthquakes in the oceanic crust and in the slab occur down to a depth of 40-60km and the PHS has the deeper aseismic portion.In the northeast Japan, we can successfully catch the slab layering struct … More ure. Namely, we can clearly image the top of the subducting Pacific slab, the oceanic Moho and surprisingly the bottom of the slab. And the RFs suggest the existence of seismic discontinuity structure corresponding to the lower seismic zone in the double seismic zone. These new findings impose strong constraints on the thermal structure and the material composition in and around the subducting slab.For the deep discontinuity structure in the upper mantle, we use the data from broadband seismic stations. The 410 km discontinuity seems to be fiat except for the inside of the slab, where the 410 is elevated locally by 30 km. The 660 is gradually inclined toward the west, which depression is caused by the cold stagnant slab. In addition, examination of frequency dependence of RF amplitudes corresponding to 410 and 660 km shows that RFs in the Japan Islands has different frequency appearance comparing to those in the Korea, suggesting that there exists different amount of water in the upper mantle beneath the Japan Islands and the Korea. Less