An Experiment in Seismic Tomography: The Three-Dimensional Structure of the East Pacific Rise

了解在中部形成新海底的过程 洋脊是海洋地质的一个重要方面， 地球物理研究 尽管现在人们普遍认为， 海底扩张造就了现在的洋壳， 大约在过去的2亿年里， 新的火山物质生成并侵位在海脊处 仍然没有解决。 一个重要的未知数是分布和 部分熔融的地下岩浆房的寿命 地幔物质在喷发到海底之前被储存起来。 最近获得的深穿透地震反射数据来自 东太平洋隆起显示了 一个相当连续的岩浆房沿着上升峰。 本项目的目的是利用地震 折射技术来更详细地研究岩浆房 而不是从地震反射数据中获得的。 具体来说，该项目将部署一系列海底 地震仪/水听器跨越上升峰，然后使用 爆炸和声学能源，以记录水平 能量通过地壳的传输。 这些数据将 通过最近开发的层析成像技术进行分析， 使用整个数据集的三维成像。 具体 要解决的问题包括宽度、深度和速度 地下岩浆房的结构 这是伍兹科学家之间的合作项目 霍尔海洋研究所和马萨诸塞州海洋研究所 技术. 该项目将在以下各级得到资助： 伍兹霍尔 -87财年= 30000美元，88财年= 297000美元，89财年= 87000美元 MIT -87财年= 30000美元，88财年= 163000美元，89财年= 133000美元

Understanding the processes that create new seafloor at mid- ocean ridges is a critical aspect of marine geological and geophysical research. Although it is now well accepted that seafloor spreading has created the present ocean crust during approximately the last 200 million years, the details by which new volcanic material is generated and emplaced at the ridges remains unresolved. An important unknown is the distribution and longevity of subsurface magma chambers in which partially melted mantle material is stored before being erupted to the seafloor. Recently acquired deep penetration seismic reflection data from the East Pacific Rise has revealed what appears to be the top of a fairly continuous magma chamber along the Rise crest. The objective of the present project is to use seismic refraction techniques to examine the magma chamber in more detail than can be obtained from the seismic reflection data. Specifically, the project will deploy a series of ocean bottom seismometer/hydrophones across the Rise crest and then use explosive and acoustic energy sources to record the horizontal transmission of energy through the crust. These data will be analyzed by recently developed tomographic techniques which allow three dimensional imaging using the entire data set. Specific questions to be addressed include the width, depth, and velocity structure of the subsurface magma chamber. This is a cooperative project between scientists at Woods Hole Oceanographic Institution and the Massachusetts Institute of Technology. The project will be funded at the following levels: Woods Hole -FY87=$30000, FY88=$297000, FY89=$87000 MIT -FY87=$30000, FY88=$163000, FY89=$133000