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，北美克拉通的中部地区经历了一系列超过Laruentide冰盖终点的大（M6）地震。对这些地震的机制知之甚少。本研究的主要目标是评估岩石圈弯曲的后果与更新世冰盖加载上的孔隙压力异常和地震活动的建立和保存内的元古代结晶基底和上覆的沉积岩的密歇根州和伊利诺伊州盆地。我们假设，剪切应力建立在上地壳（10-20公里深）以外的冰盖终端导致孔隙压力增加，在低渗透性的环境能够诱发地震事件。在密歇根盆地东侧拟议的加拿大核废料储存库所在地观察到的负压，应该发生在今天经历反弹的前冰川地区。使用COMSOL，我们将开发一个二维地质力学-水文-溶质运移模型，能够代表岩石圈挠曲和孔隙弹性变形以及软流层和地下水流。我们将利用一个简单的莫尔-库仑破坏准则作为衡量确定地区的地球？可能会破裂的地壳。该模型的地面实况将包括中大陆全新世和人类世地震的位置和（如可能）深度，以及伊利诺伊州和密歇根州盆地储层和封闭单元的孔隙压力/盐度/同位素数据。隔离高放射性核废料需要考虑未来的水文和地貌条件，时间尺度可达100万年。该项目的结果应与位于高纬度国家（北纬40度）的国家（如加拿大、瑞典、瑞士和芬兰）的核废料隔离计划特别相关。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物管理组织（NWMO）和瑞典核废物管理局（SKB）。这项工作也可能是有益的群体研究诱发地震活动在大陆中部通过识别地区的地球？它的地壳可以保持高的流体压力，并容易失败。该项目将在为少数民族服务的机构NM Tech培训一名研究生。将努力从任职人数不足的群体中征聘一名妇女和（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.