Seismic Probing of the Ontong-Java Plateau: A Passcal Experiment

9218907 OKAL本次研究是为了研究安通-爪哇高原的地震构造，该高原是洋底火成岩活动最大的表现。由PASSCAL仪器组成的四个地震台将在密克罗尼西亚群岛丘克、波恩佩、科斯雷和瑙鲁部署两年。所罗门俯冲带的震源将被用来调查高原上面波的频散，以测量深度为200公里的地震结构。同时，针对该地区地壳和上地幔的结构各向异性，将进行一系列体波实验。预计这项工作将为地壳的确切厚度、深部地壳的性质、高原地幔(盖子和下伏低速带)的结构以及上地幔各向异性的程度和方向等问题提供答案。反过来，这些参数又将制约白垩纪高原侵位的环境和机制。***

9218907 Okal This research is to study the seismic structure of the Ontong- Java Plateau, the largest expression of igneous activity of the ocean floor. Four seismic stations composed of PASSCAL instruments will be deployed for two years on the Micronesian islands of Chuuk, Pohnpei, Kosrae and Nauru. Earthquake sources in the Solomon subduction zone will be used to investigate the dispersion of surface waves over the plateau to measure seismic structure to depths on the order of 200 km. Concurrently, a number of body-wave experiments will be conducted targeting the structural anisotropy of the crust and upper mantle in the area. The work is expected to provide answers to such questions as the exact thickness of the crust, the nature of the deep crust, the structure of the mantle (lid and underlying low-velocity zone) of the plateau, and the extent and direction of anisotropy in the upper mantle. In turn, these parameters will put constraints on the environment and mechanism of emplacement of the plateau in the Cretaceous. ***