Collaborative Research: Normal-Fault Facets as Recorders of Erosion and Tectonics

地震是昂贵而危险的自然灾害。管理它们所代表的风险需要估计过去地质时期地震的大小和频率。通常，这种知识依赖于特定断层过去活动的信息，很难获得，而且代价高昂。本项目试验了一种通过详细的实地测量和简单的数学模型来估计过去地震活动的新方法。由于这些地区的山地地形也是气候的产物，因此收集到的数据将提供有关过去一到两个冰期期间风化和侵蚀速率变化的信息。这些关于气候和侵蚀之间关系的信息对于各种应用都很重要，包括石油和天然气工业用来研究沉积矿床形成的长期沉积模型。该项目还将通过培养一名博士后研究助理来促进教育，并将通过为来自代表性不足的少数群体的学生提供本科暑期研究经验来扩大对科学的参与。该项目与挪威卑尔根大学和英国伦敦大学有着强有力的国际合作。这项研究将有助于理解气候对自然速率和侵蚀过程的控制以及古地震学。该项目测试了一种估算过去地震活动的新方法，方法是对断层附近的山脉的形状和陡峭度进行详细测量，这些山脉是由断层上的运动造成的。该方法依赖于一个简单的山前形态数学模型，该模型预测了断层运动的平均速率与邻近地形的陡峭度之间的定量关系。该项目将通过研究两个地方来测试这个模型，这两个地方已经有独立的断层运动速率估计：犹他州的瓦萨奇山脉和意大利的亚平宁山脉中部。详细测量这两个地点活动断层附近的景观形态，并检查随着时间的推移改变地形的风化和侵蚀过程，将为这种方法重建过去断层活动的效果提供测试。研究内容包括野外调查、数字地形分析、宇宙成因核素分析、坡面分析作为古地震学工具的可行性测试等。该项目由地貌学与土地利用动力学、构造学和国际科学与工程项目联合支持。

Earthquakes are expensive and dangerous natural hazards. Managing the risk they represent requires estimating the size and frequency of earthquakes in the geologic past. Often, this knowledge, which relies on information about the past activity of particular faults, is difficult and costly to obtain. This project tests a new method for estimating past earthquake activity through detailed field measurements and a simple mathematical model. Because mountain topography in these settings is also a product of climate, the data collected will provide information on variations in rates of weathering and erosion during the past one to two ice ages. Such information about the relationship between climate and erosion is important for a variety of applications, including models of long-term sedimentation that the oil and gas industry uses to study the formation of sedimentary deposits. The project will also foster education by training a post-doctoral research associate, and it will broaden participation in science by providing an undergraduate summer research experience for a student from an under-represented minority group. The project has a strong international collaboration with the University of Bergen in Norway and the University of London in the UK. This research will contribute both to an understanding of climate control on natural rates and processes of erosion as well as paleoseismology. The project tests a new method for estimating past earthquake activity through detailed measurements of the shape and steepness of mountains that lie next to faults, and which were created by motion on those faults. The method relies on a simple mathematical model for mountain-front form that predicts a quantitative relationship between the average rate of fault motion and the steepness of the adjacent terrain. The project will test this model by studying two locations where independent estimates of fault-motion rate are already available: the Wasatch Mountains, Utah, and the central Apennines Mountains, Italy. Measuring in detail the landscape form adjacent to active faults in these two sites, and examining the processes of weathering and erosion that modify topography over time, will provide a test of how well this method works to reconstruct past fault activity. The research includes field surveys, digital topography analysis, cosmogenic nuclide analysis, and feasibility testing of facet-slope analysis as a paleoseismology tool. This project is jointly supported by the Geomorphology and Land Use Dynamics, Tectonics, and International Science and Engineering programs.