The Hydromechanical Wild Card: The Role of Ice Sheets in Crustal Stress Changes, Anomalous Pore Pressures Generation and Seismicity within the Midcontinent Region of North America

在全新世和人类世期间，北美克拉通的中等含量地区经历了拉伦蒂德冰盖末端以外的一些大地震(6级)。人们对这些地震的机制知之甚少。这项研究的主要目的是评估与更新世冰盖负载相关的岩石圈挠曲对密歇根和伊利诺伊盆地元古界结晶基底和上覆沉积岩内孔压异常和地震活动的建立和保存的影响。我们假设，在冰盖末端以外的上地壳(10-20公里深)内积累的剪应力会在能够诱发地震事件的低渗透环境中引起孔压增加。压力不足，例如在密歇根盆地东侧拟议的加拿大核废料储存库地点观察到的压力，应该会出现在今天正在反弹的以前的冰川地区。利用COMSOL，我们将开发一个能够描述岩石圈弯曲和孔洞弹性变形以及软流圈和地下水流动的二维地质力学-水文-溶质运移模型。我们将使用一个简单的摩尔-库仑破坏准则作为一个度量标准来确定地球上可能发生破坏的区域--S地壳。该模型的实际情况将包括中大陆全新世和人类世地震的位置和深度，以及来自伊利诺伊州和密歇根盆地的水库和封闭单元的孔压/盐度/同位素数据。分离高放射性核废料需要在长达一百万年的时间尺度上考虑未来的水文和地形条件。该项目的成果应特别适用于位于高纬度国家(40°N)的国家的核废料隔离计划，例如加拿大、瑞典、瑞士和芬兰。所有这些国家都可能经历未来的冰川。项目成果将提供给加拿大核废料管理组织(NWMO)和瑞典核废料管理署(SKB)。这项工作也可能有助于研究中大陆诱发地震活动的团队，通过识别地球上可以保持高流体压力和容易失败的区域--S地壳。该项目将在NM理工学院培养一名研究生，这是一家为少数族裔服务的机构。将努力从任职人数不足的群体中招聘一名妇女和/或一名个人。

The midcontent region of the North American craton has experienced a number of large ( M6) earthquakes beyond the terminus of the Laruentide Ice Sheet during the Holocene and Anthropocene. The mechanisms responsible for these earthquakes are poorly understood. The main goal of this study is to assess the consequences of lithosphere flexure associated with Pleistocene ice-sheet loading on the build up and preservation of pore pressure anomalies and seismicity within the Proterozoic crystalline basement and overlying sedimentary rocks of the Michigan and Illinois Basins. We hypothesize that shear stress build up within the upper crust (10-20 km depth) beyond the ice sheet terminus causes pore pressure increases within low-permeable environments capable of inducing seismic events. Underpressures, such as those observed at the proposed Canadian nuclear waste repository site on the eastern flank of the Michigan Basin, should occur in formerly glaciated areas undergoing rebound today. Using COMSOL, we will develop a two-dimensional geomechanical-hydrologic-solute transport model capable of representing lithosphere flexure and poro-elastic deformation as well as asthenosphere and groundwater flow. We will utilize a simple Mohr-Coulomb failure criteria as a metric for determining regions of the Earth?s crust that are likely to fail. Ground truth for this model will include the position and (where possible) depths of midcontinent Holocene and Anthropocene earthquakes as well as pore pressure/salinity/isotopic data from reservoirs and confining units of the Illinois and Michigan Basins. Isolating high-level nuclear waste requires consideration of future hydrologic and geomorphic conditions on time scale of up to one million years. The results of this project should be especially relevant to nuclear waste isolation programs in countries located at high latitude countries ( 40o N) such as those in Canada, Sweden, Switzerland, and Finland. All of these countries could experience future glacations. Project results will be made available to the Canadian Nuclear Waste Management Organization (NWMO) and the Swedish Nuclear Waste Management Agency (SKB). This work may also be of benefit to groups studying induced seismicity within the midcontinent by indentifying regions of the Earth?s crust that could preserve high fluid pressures and would be prone to failure. This project will train one graduate student at NM Tech, a minority-serving institution. Effort will be made to recruit a woman and/or an individual from an under-represented group.