Collaborative Research: Crustal Deformation Measurements and a Multidisciplinary Geophysical Investigation of the Rio Grande Rift

合作研究：里奥格兰德裂谷的地壳变形测量和多学科地球物理调查

• 批准号: 0454372
• 负责人: Mousumi Roy
• 金额: $ 12.42万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0454372&HistoricalAwards=false
• 关键词: Collaborative; Research; Crustal; Deformation; Measurements

0454372RoyThe Rio Grande rift is the easternmost deforming province within the tectonically active western margin of North America. Located just east of the Colorado Plateau, the rift is undergoing stretching and extension manifested by slightly higher probabilities of earthquake occurrence than in surrounding regions. Rates of motion are estimated at sub-mm to 5 mm/yr, but uncertainties in measurements of total extension are typically of the same order as the estimates themselves. This project brings together a team of researchers from the University of Colorado Boulder and the University of New Mexico to establish current rates of motion along the Rio Grande rift with high precision. The team is measuring rift motions using state-of-the-art global positioning system (GPS) instruments at 24 sites in Colorado and New Mexico. Each measurement epoch lasts six months and data are being collected for four epochs, providing rates encompassing a three-year span. The slow rates of motion in the region make this project especially challenging. The monumentation, observing time, and innovative post-processing strategies are designed to optimally resolve deformation at the sub-millimeter per year scale. A primary goal of the project is to understand what stretching rates measured at the surface imply about the stretching of the plate at deeper levels. An intriguing possibility is that stretching in the Rio Grande rift is heterogeneous, with different processes operating in the crust and the mantle. Available geologic observations also suggest that the character of the rifting changes dramatically from north to south, with a narrow rift zone marked by linear topographic depressions in Colorado and northern New Mexico grading to a broad region of multiple valleys ("basin and range") in south-central New Mexico. The factors that drive this variable character of the Rio Grande rift are not well-understood, but could have significant bearing on our understanding of how and why tectonic plates undergo stretching and of earthquake and volcanic hazards within rift zones. To examine these issues, the team is comparing their measured rates of motion with all other available datasets, including seismic velocities in the crust and mantle, gravity, surface heat flow, and geologic data. These diverse datasets are being used to build computer models of processes that control how tectonic plates undergo rifting. The project involves training graduate and undergraduate students in GPS measurement and analysis and spreading the group's knowledge in a variety of ways, including: training K-12 school teachers in the research process (the 'Earthworks' project of the Cooperative Research in Environmental Sciences at CU Boulder); involving middle schools in the siting and "adoption" of GPS sites; and interactions with agencies interested in earthquake and volcanic hazards along the Rio Grande rift including state Geological surveys, local and federal emergency management agencies, local governments, city planners, and engineers.

0454372罗伊格兰德河裂谷是北美构造活动活跃的西缘最东部的变形省份。该裂谷位于科罗拉多高原以东，正在经历拉伸和延伸，其地震发生概率略高于周边地区。运动速率估计为亚毫米至 5 毫米/年，但总伸展测量的不确定性通常与估计本身具有相同的数量级。该项目汇集了科罗拉多大学博尔德分校和新墨西哥大学的研究人员团队，以高精度确定格兰德河裂谷当前的运动速率。该团队正在科罗拉多州和新墨西哥州的 24 个地点使用最先进的全球定位系统 (GPS) 仪器测量裂谷运动。每个测量时期持续六个月，并收集四个时期的数据，提供涵盖三年跨度的比率。该地区的缓慢运动速度使该项目特别具有挑战性。纪念、观测时间和创新的后处理策略旨在以最佳方式解决每年亚毫米规模的变形。该项目的主要目标是了解在表面测量的拉伸率意味着板在更深层次上的拉伸。一个有趣的可能性是，格兰德河裂谷的伸展是不均匀的，地壳和地幔中发生着不同的过程。现有的地质观测还表明，裂谷的特征从北到南发生了巨大的变化，科罗拉多州和新墨西哥州北部有一个以线性地形洼地为标志的狭窄裂谷带，逐渐过渡到一个由多个山谷（“盆地和山脉”）组成的广阔区域。新墨西哥州中南部。导致里奥格兰德裂谷这种多变特征的因素尚不清楚，但可能对我们理解构造板块如何以及为何发生拉伸以及裂谷区内的地震和火山灾害具有重大影响。为了研究这些问题，该团队将他们测量的运动速率与所有其他可用的数据集进行比较，包括地壳和地幔的地震速度、重力、表面热流和地质数据。这些不同的数据集被用来构建控制构造板块如何发生裂谷的过程的计算机模型。该项目包括对研究生和本科生进行 GPS 测量和分析方面的培训，并以多种方式传播小组的知识，包括： 在研究过程中对 K-12 学校教师进行培训（环境科学合作研究的“Earthworks”项目）科罗拉多大学博尔德）；让中学参与 GPS 站点的选址和“采用”；以及与对格兰德大裂谷沿线的地震和火山灾害感兴趣的机构的互动，包括州地质调查、地方和联邦应急管理机构、地方政府、城市规划者和工程师。