Collaborative Research: Upper Mantle Structure Beneath the Gulf of California

在这个实验中，是美国国家科学基金会裂谷大陆岩石圈边缘计划的一部分，研究人员在加利福尼亚湾部署了18个宽带海底地震仪（OBS），为期15个月。这些地震仪记录了全球各地自然发生的地震活动（超过200次中、大地震）。利用这些地震记录，研究人员正在构建墨西哥湾及其周边地区的地幔图像，为评估地幔过程控制岩石圈破裂和加利福尼亚湾海底扩张的程度提供了一种手段。实验集中在两个问题上，这两个问题对于实现裂谷大陆岩石圈倡议的目标尤为重要：(1)直接位于加利福尼亚湾延伸下的上地幔是否异常热？(2)伸展样式的南北变化在多大程度上与上地幔速度变化相关？OBS的部署还提供了更好地表征加利福尼亚湾地震活跃断层的手段，改进了该地区自然灾害环境的评估。加利福尼亚湾OBS阵列建立了两个正在进行的边际资助实验：NARS-Baja陆上宽带地震阵列和一个有源地壳调查。本实验收集的海底地震数据将在仪器回收后2年内通过IRIS数据管理中心提供给任何感兴趣的研究者。

In this experiment, which is part of the NSF Margins initiative on Rifting Continental Lithosphere, the investigators are deploying 18 wide-band ocean bottom seismographs (OBS) in the Gulf of California for a period of 15 months. These seismographs are recording naturally occurring seismicity (over 200 moderate and large earthquakes) from around the globe. Using these seismic recordings, the investigators are constructing images of the mantle beneath the Gulf and the surrounding region, providing a means to evaluate the degree to which mantle processes control lithospheric rupture and the initiation of seafloor spreading in the Gulf of California. The experiment is focused on two questions that are particularly important for achieving the goals of the Rifting Continental Lithosphere initiative: (1) Is the upper-mantle directly underlying Gulf of California extension anomalously hot? (2) To what extent do North-South variations in extensional style correlate with upper-mantle velocity variations? The OBS deployment also provides the means to better characterize seismically active faults within the Gulf of California, improving the assessment of the natural hazards environment of the region. The Gulf of California OBS array builds two ongoing Margins-funded experiments: the NARS-Baja onshore broadband seismic array, and an active-source crustal survey. The ocean-bottom seismic data collected in this experiment will be available to any interested investigator 2 years following instrument recovery through the IRIS Data Management Center.