无萼的

The existences of these discontinuities show obvious regional characteristics that,(1) at the northern Izu-Bonin which is north to latitude of 33°, the SV-P converted phases following the phases from the 660km discontinuity are relatively weak,(2) at the southern part which is south to latitude of 29°, all phases are relatively strong, even some phases' amplitudes are comparative with those from the 660km discontinuity, and (3) at the part of Izu-Bonin between the latitude between 30°and 32°, all converted phases are relatively weak except the clear phases from the 660km discontinuity.

从各地震的波形叠加结果看，这些间断面的存在情况明显具有区域性特征：在北部，北纬33°以北在来自660km间断面的转换震相之后出现的SV-P转换震相相对较弱；在南部，北纬29°以南则各转换震相相对较强，有的幅度可以与来自660km间断面的转换震相的幅度相比；而北纬30°～32°之间除了来自660km间断面的转换震相存在比较清晰以外，后至的转换震相都相对较弱。