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，北美克拉通中部地区在Laruentide冰原末端以外经历了多次大地震（M6）。人们对这些地震的机制知之甚少。本研究的主要目的是评估与更新世冰盖负荷相关的岩石圈弯曲对密西根和伊利诺斯盆地元古代结晶基底和上覆沉积岩中孔隙压力异常和地震活动的形成和保存的影响。我们假设，在冰盖末端以外的上地壳（10-20公里深度）内积聚的剪切应力导致能够诱发地震事件的低渗透环境中的孔隙压力增加。在密歇根盆地东侧拟议的加拿大核废料处置场所观察到的压力不足，应该出现在今天正在反弹的以前冰川地区。利用COMSOL，我们将建立一个二维地质力学-水文-溶质输运模型，该模型能够表示岩石圈弯曲和孔隙弹性变形，以及软流圈和地下水流动。我们将使用简单的莫尔-库仑失效准则作为确定地球区域的度量标准。可能会破裂的美国地壳。该模型的基础数据将包括全新世和人类世中部大陆地震的位置和深度（如果可能的话），以及伊利诺伊和密歇根盆地储集层和围合单元的孔隙压力/盐度/同位素数据。隔离高放核废料需要在长达100万年的时间尺度上考虑未来的水文和地貌条件。该项目的结果应特别适用于位于高纬度国家（北纬40度）的核废料隔离方案，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期。项目结果将提供给加拿大核废料管理组织和瑞典核废料管理机构。这项工作也可能对通过确定地球区域来研究大陆中部诱发地震活动的小组有益。美国地壳可以保持高流体压力，并且容易破裂。该项目将在为少数族裔服务的NM Tech培养一名研究生。将努力从代表性不足的群体中征聘一名妇女和/或个人。

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.