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.

0454372ROYTHERYTHE RIO GRANDE RIFT是北美构造活跃的西部边缘内最东部的变形省。裂谷位于科罗拉多高原的东部，正经历着伸展，并且延伸表现为地震发生的概率略高于周围地区。运动速率估计为低于mm至5 mm/yr，但总扩展的测量值的不确定性通常与估计本身的顺序相同。该项目汇集了科罗拉多大学博尔德大学和新墨西哥大学的一组研究人员，以高精度沿里奥格兰德裂谷建立当前的运动率。该团队正在使用科罗拉多州和新墨西哥州24个地点的最先进的全球定位系统（GPS）仪器来衡量裂谷运动。每个测量时期持续六个月，并且正在为四个时期收集数据，提供了包括三年跨度的费率。该地区的运动速度缓慢使该项目特别具有挑战性。纪念碑，观察时间和创新的后处理策略旨在以每年的次数量表来最佳解决变形。该项目的主要目标是了解表面上测量的拉伸速率暗示板在更深层次的水平上的拉伸。一个有趣的可能性是，里奥格兰德裂谷中的伸展是异质的，在地壳和地幔中运作不同的过程。可用的地质观察还表明，裂谷的特征从北向南变化很大，裂谷区域狭窄的区域是科罗拉多州和北部新墨西哥州的线性地形下降标记，在新墨西哥州南部中部的多个山谷（“盆地和范围”）的广泛地区分级。驱动里奥格兰德裂谷（Rio Grande Rift）变量特征的因素并没有得到充分理解，但可能与我们对构造板的理解以及为什么在裂谷区内进行地震和火山危害的理解有重要意义。为了检查这些问题，团队将其测量的运动速率与所有其他可用数据集进行了比较，包括地壳和地幔中的地震速度，重力，表面热流量和地质数据。这些不同的数据集用于构建计算机模型的流程模型，以控制构造板如何进行裂缝。该项目涉及培训毕业生和本科生在GPS测量和分析中以各种方式传播小组的知识，包括：在研究过程中培训K-12学校教师（Cu Boulder环境科学合作研究的“ Earthworks”项目）；让中学参与GPS网站的选址和“收养”；以及与里奥格兰德裂谷沿线的地震和火山危害感兴趣的机构的互动，包括州地质调查，地方和联邦紧急管理机构，地方政府，城市规划师和工程师。