Temporal Changes in Permeability Induced by Seismicity

地震活动引起的渗透率随时间的变化

• 批准号: 9405631
• 负责人: Stuart Rojstaczer
• 金额: $ 19.01万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-15 至 1998-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9405631&HistoricalAwards=false
• 关键词: Temporal; Changes; Permeability; Induced; Seismicity

9405631 Rojstaczer This study proposes to extend work on the causes and timing of temporal changes in permeability induced by seismicity. The research is designed to obtain a more definitive understanding of the coupling that exists between fault motion and hydrology. Such information provides constraints on the time dependence of the hydrology of the shallow crust. The research also has application to the storage of high level radioactive waste at Yucca Mountain and to understanding the timing and location of major ore and hydrocarbon deposits. Finally, it may also provide prehistoric information on the rupture cycle of the San Andreas Fault. The project will examine: whether ground motion induced shear stress is capable of generating increases in permeability near the San Andreas fault; and whether the influence of seismicity on groundwater flow over geologic time can be seen in the rock record. The field aspects of the research will focus on the San Lorenzo drainage basin. This basin accounted for 35% of the excess streamflow produced by the Loma Prieta earthquake (10/17/89, M 7.0) and has already been studied extensively by the PI. Hydraulic fracture tests will be performed in granodiorite on the edge of the San Lorenzo drainage basin. The results from these tests will be used in conjunction with models of ground-motion induced shear stress to examine the constraints on ground motion induced permeability enhancement. These constraints will be used to test whether permeability enhancement can explain the spatial patterns of earthquake-induced hydrologic change in the region. Core will be obtained from the granodiorite to a depth of 300 m for petrologic analysis of the calcite cement which partially fills fractures. The influence of pre-historic faulting on subsurface hydrology will be examined by analyzing the isotopic signature of calcite fracture fills in the existing and newly obtained core. The research will be done in cooperation wit h Stephen Hickman of the U.S. Geological Survey who will provide all of the equipment and manpower associated with the hydraulic fracturing tests. Funds for Stephen Hickman's portion of the project will be provided by the US. Geological Survey.

9405631 Rojstaczer 这项研究建议扩大对地震活动引起的渗透率时间变化的原因和时间的研究。 该研究旨在更明确地了解断层运动与水文之间存在的耦合。 这些信息对浅地壳水文学的时间依赖性提供了限制。 该研究还适用于尤卡山高放射性废物的储存以及了解主要矿石和碳氢化合物矿藏的时间和位置。 最后，它还可能提供有关圣安德烈亚斯断层破裂周期的史前信息。 该项目将研究： 地面运动引起的剪切应力是否能够增加圣安德烈亚斯断层附近的渗透率；地质时期地震活动对地下水流的影响是否可以在岩石记录中看到。 研究的实地方面将集中在圣洛伦索流域。 该流域占洛马普列塔地震（89 年 10 月 17 日，震级 7.0）产生的过剩水流的 35%，并且已被 PI 广泛研究。 水力压裂试验将在圣洛伦索流域边缘的花岗闪长岩中进行。这些测试的结果将与地面运动引起的剪应力模型结合使用，以检查地面运动引起的渗透性增强的约束。这些约束将用于测试渗透性增强是否可以解释该地区地震引起的水文变化的空间模式。 将从花岗闪长岩中获取 300 m 深度的岩心，用于部分填充裂缝的方解石胶结物的岩石学分析。 通过分析现有和新获得的岩心中方解石裂缝填充物的同位素特征，将研究史前断层对地下水文的影响。 该研究将与美国地质调查局的斯蒂芬希克曼合作完成，后者将提供与水力压裂测试相关的所有设备和人力。 斯蒂芬·希克曼项目部分的资金将由美国提供。地质调查。