COLLABORATIVE RESEARCH: Geodetic measurements and mechanical models of rifting in onshore segments of mid-ocean ridges.

这项提案支持的研究是威斯康星大学和阿拉巴马大学塔斯卡卢萨分校的美国科学家以及他们的冰岛同事之间的国际合作，旨在量化岩浆作用在适应洋中脊扩张中的作用。研究人员正在进行一项脉冲响应实验，其中脉冲是岩浆在裂缝处的注入，而响应是由测地线和地震学方法记录的变形。研究的重点是1975-1984年冰岛克拉夫拉北部火山带的一次侵入事件，由于堤防的侵入，轴谷的宽度增加了几米，导致一个世纪？以每年约2厘米的长期平均速度扩散。岩浆供应减少后，这种延伸会持续数年或数十年，最终随着应力的放松而减缓。该研究解决了以下问题：(1)岩浆管道的几何形状是什么？(2)管道内岩浆压力如何随时间演化？(3)断裂构造的材料特性是什么？要定量回答这些问题，就需要回答一个更基本的问题：哪种本构关系（流变学）最能描述岩石圈以下的岩石？因此，研究的主要目的是确定本构关系和流变特性控制裂谷。这项研究有助于理解大洋中脊的裂谷机制，这是板块构造学的一个基本过程。这项研究促进了博士研究生的培养，并支持了一位早期职业科学家的研究工作。研究结果和在此研究期间制定的建模协议将在地质界传播。从社会的角度来看，这项研究使人们对与裂谷事件有关的岩浆和地震灾害有了更广泛的了解。这项研究得到了地球物理项目和海洋地质与地球物理项目的支持。

The research supported by this proposal is an international collaboration between U.S. scientists from the University of Wisconsin and the University of Alabama-Tuscaloosa and their Icelandic colleagues that is aimed at quantifying the role of magmatism in accommodating spreading at mid-oceanic ridges. The investigators are performing an impulse-response experiment, in which the impulse is the injection of magma at the rift, and the response is the deformation recorded by geodesic and seismological methods. The research focuses on extension related to an intrusive event from the northern volcanic zone of Krafla in Iceland in 1975-1984, where the width of the axial valley was increased by several meters due to the intrusion of dikes, resulting in a century?s worth of spreading at the long-term average rate of about two centimeters per year. After the magma supply diminishes, the extension continues over years or decades, and finally slows as the stresses relax. The research is addressing the following questions: (1) What is the geometry of the magmatic plumbing? (2) How does the magmatic pressure in the plumbing evolve with time? (3) What are the material properties of the rift structure? Providing quantitative answers to these questions requires answering a more fundamental question: which constitutive relation (rheology) best describes the rock below the lithosphere? Accordingly, the primary goal of the research is determining the constitutive relations and rheologic properties governing rifting. The research is contributing to the understanding of the mechanics of rifting at mid-ocean ridges, a fundamental process in plate tectonics. The research is fostering the training of a doctoral graduate student and is supporting the research efforts of an early career scientist. Research results and the modeling protocols developed during this study will be disseminated among the geological community. From a societal standpoint, the research is leading to a broader understanding of magmatic and seismological hazards associated with rifting events. The research is supported by the Geophysics Program and Marine Geology and Geophysics Programs.