Collaborative Research: Geodetic Constraints on the Kinematics of the Colorado Plateau and its Western and Southern Margin

合作研究：对科罗拉多高原及其西部和南部边缘运动学的大地测量限制美国西南部的科罗拉多高原在太平洋-北美板块边界带的地质演化中发挥了重要作用。与美国西部的大多数其他地区不同，科罗拉多高原在其地质历史的大部分时间里基本保持完好。事实上，该地区几乎没有活动的地震断层。然而，科罗拉多高原内确实发生了地震，亚利桑那州南部和墨西哥北部发生了一些非常大的地震。该项目使用精确的GPS测量来确定科罗拉多高原的地壳相对于稳定的北美是如何移动的。对水平速度的解释告诉调查人员，该地区是作为一个连贯的地块运动，还是在内部变形。在前一种情况下，预计地震活动不会太大，而在后一种情况下，该地区的地震危险性可能比目前认为的要高。将GPS数据和地震数据隐含的形变进行了比较，以评估地震活动是否与本项目测量的形变有关，或者是否由重力坍塌等其他过程引起。为了进行测量，在亚利桑那州、犹他州南部和内华达州东南部安装了33个新的GPS站。这些观测站补充和加强了NSF地球望远镜的板块边界观测站的长期运行的连续GPS观测站。需要更多的空间站来创建约束良好的模型，以描述该地区的现代构造。通过一个良好约束的形变模型，可以研究科罗拉多高原的运动和变形的起源。其中一些被考虑的模型包括高原的刚性运动导致里奥格兰德裂谷的打开，地壳伸展由于地幔过程的演化而侵蚀高原，以及太平洋板块运动对南部盆地和山脉变形的影响。许多新的GPS站安装在国家公园和纪念碑以及国家公园。调查人员提供教育材料，向公园通报该地区的活动构造和该项目的目标。这些外展活动的目的是教育公园的游客，他们所处的地质仙境正在由于地质过程而发生积极变化。测量时间为四年，该项目涉及一名研究生的培训。该项目的成果可用于S城市中心区地震危险性的重新评估。

Collaborative Research: Geodetic Constraints on the Kinematics of the Colorado Plateau and its Western and Southern MarginThe Colorado Plateau, southwestern United States, has played an important role in the geologic evolution of the Pacific-North America plate boundary zone. Unlike most other parts of the western U.S., the Colorado Plateau has remained largely intact during most of its geologic history. Indeed, the area shows little to none active earthquake faults. However, earthquakes do happen within the Colorado Plateau, and some very large ones have occurred in southern Arizona and northern Mexico.This project uses precise GPS measurements to establish how the crust of the Colorado Plateau moves relative to stable North America. Interpretation of the horizontal velocities tells the investigators whether the area moves as a coherent block or is internally deforming. In case of the former little earthquake activity is expected, and in case of the latter the seismic hazard in the region may be higher than currently thought. The deformation implied by the GPS data and earthquake data is compared in order to assess whether the earthquake activity can be related to the deformation measured in this project or whether they are due to other processes, such as gravitational collapse. To perform the measurements, 33 new GPS stations are installed in Arizona, southern Utah and southeastern Nevada. These stations complement and densify the long-running continuous GPS stations of NSF EarthScope's Plate Boundary Observatory. The additional stations are needed to create well-constrained models to describe the region's present-day tectonics. With a well-constrained model of the deformation can the origin of the motion and deformation of the Colorado Plateau be investigated. Some of the models that are considered include a rigid motion of the plateau causing opening of the Rio Grande Rift, crustal extension encroaching into the plateau due to evolving mantle processes, and the effect of Pacific plate motion on the deformation of the southern Basin and Range.Many of the new GPS stations are installed in National Parks and Monuments, as well as in State Parks. The investigators provide educational material to inform the parks on the active tectonics of the region and the aim of the project. The goal of these outreach activities is to educate the parks' visitors that the geologic wonderland they are in is actively changing due to geologic processes. Measurements are made for four years and the project involves training of a graduate student. The outcome of this project may be used in a reassessment of the seismic hazard in the region?s urban centers.