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

地震层析成像实验：东太平洋海隆的三维结构

• 批准号: 8615892
• 负责人: Sean Solomon
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-04-15 至 1990-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8615892&HistoricalAwards=false
• 关键词: Experiment; Seismic; Tomography; Three; Dimensional

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

了解在洋中脊形成新海底的过程是海洋地质和地球物理研究的一个重要方面。虽然现在人们普遍认为，在过去大约2亿年里，海底扩张形成了现在的海洋地壳，但是新的火山物质是如何产生并安置在山脊上的细节仍未得到解决。一个重要的未知因素是地下岩浆房的分布和寿命，部分融化的地幔物质在喷发到海底之前被储存在地下岩浆房中。最近从东太平洋隆起获得的深穿透地震反射数据显示，沿着隆起的顶部似乎有一个相当连续的岩浆房。本项目的目的是利用地震折射技术对岩浆房进行比地震反射数据更详细的检查。具体来说，该项目将在Rise波峰上部署一系列海底地震仪/水听器，然后使用爆炸和声能源记录能量通过地壳的水平传输。这些数据将通过最近开发的层析成像技术进行分析，该技术允许使用整个数据集进行三维成像。需要解决的具体问题包括地下岩浆房的宽度、深度和速度结构。这是伍兹霍尔海洋研究所和麻省理工学院科学家之间的合作项目。该项目将按以下级别资助：伍兹霍尔-FY87= 30000美元，FY88= 297000美元，FY89= 87000美元麻省理工学院-FY87= 30000美元，FY88= 163000美元，FY89= 133000美元