Development of a seismic network over the Pacific islands

1993年3月，我们在密克罗尼西亚的太平洋岛上建立了一个新的PATS站，为此我们开发了一种新的连续模式记录系统。我们测量了从马里亚纳到帕特斯(纯粹的马里亚纳海盆)和从所罗门岛(纯粹的安通爪哇高原)的路径在20-150秒的时间内的瑞利波群速度。马里亚纳盆地是太平洋最古老的海底(16 Ma)，安通爪哇高原是海底的熔岩高原。得到马里亚纳盆地瑞雷波频散曲线较快，安通爪哇高原瑞利波频散曲线较低。两条路径的频散曲线具有明显的反差，在此基础上建立了剪切速度模型。马里亚纳盆地至少有120公里厚的板块，其速度快于标准海洋模型，标准海洋模型是太平洋上最古老的海底(160-170 Ma)。Mitchell和Yu(1980)、Yoshii(1975)研究了太平洋海底年龄与表面波速度之间的关系。然而，他们的研究缺乏关于最古老海底的结果，因为马里亚纳盆地的路径复盖率很低。安通爪哇高原地壳厚度超过40公里，板块厚度超过80公里。

In March 1993, a new station PATS was established on Pacific island, Micronesia, for which we developed a new recording system in a continuous mode. We measured Rayleigh wave group velocities in a period rang 20-150s for the path from Mariana to PATS which is purely the Mariana Basin, and for the path from Solomon island which is purely the Ontong Java Plateau. The Mariana Basin is the oldest seafloor of the Pacific (>16ma) and the Ontong Java Plateau is lava plateau on the seafloor. We got a faster dispersion curve of Rayleigh wave on the Mariana Basin and a lower one on the Ontong Java Plateau. The dispersion curves for the two paths are in marked contrast on the basis of which the shear velocity models were constructed.The Mariana Basin has an at least 120km thick plate with a velocity faster than the standard oceanic model which is the oldest seafloor (160-170ma) in the pacific. Relations between the seafloor age and the surface wave velocity in the Pacific have been studied by Mitchell and Yu (1980), Yoshii (1975). However their studies lack the result for the oldest seafloor because of the poor path coverage over the Mariana Basin. The Ontong Java Plateau has thick crust more than 40km and has thick plate more than 80km.