Leveraged acquisition of a Seattle fault GPS network: Four dimensional constraint on seismic and aseismic strain accumlation and release in the urbanized Puget Lowlands

使用全球定位系统(GPS)的连续观测可以高精度地确定水平和垂直形变速率及其在时间和空间上的变化。该项目建立在太平洋西北大地测量阵列(PANGA)的区域数据在过去一年取得的惊人进展的基础上。与普吉特湾的勘测界合作，庞加科学家将安装一个连续的GPS网络，该网络经过优化设计，可以确定西雅图断裂带的运动学和锁定情况，西雅图断裂带是北美板块内的一个主要断层。此外，该网络还对最近在卡斯卡迪亚板块界面过渡区发现的缓慢或无声地震的周期性复发提供了重要的新约束。这两项研究对表征板块相互作用的地球动力学具有重要意义，对量化位于城市化普吉特低地中心的地壳断层上的地震应变能积累也有更广泛的影响。这一网络将为板块边界断层上的地震和非地震应变释放机制之间的相对平衡增加新的约束，该断层已知以大约500年的频率产生大地震(约9级)。最后，这个项目将促进区域专业人士和学术界之间的新合作。普吉特海湾测量界已经成立了一个联盟，支持将新的GPS技术协调到城市化的普吉特低地。市、县、州机构和工程公司的这项合作致力于安装一个被称为普吉特参考系统实用程序(PRSU)的“虚拟参考系统”GPS网络，该网络可以提供厘米级的实时定位。幸运的是，这个网络对于上面概述的地震和地球动力学研究是最佳的，但需要注意的是，固体地球变形社区拥有最高的纪念碑标准，以便GPS天线跟踪真实的地球运动，而不是土壤、地下水或人造结构的影响。普吉特低地给稳定的纪念碑设计带来了最大的一级挑战：厚厚的土层，西雅图断层脚下的深沉积盆地，以及最后一次冰川消退时留下的一层碎屑，需要使用深锚固的钻孔支撑纪念碑。因此，这样的纪念碑对于在地球物理上有意义的观测是至关重要的，因为这里提出的问题需要高精度的观测。该项目为具有大地测量质量的古迹提供资金，以便以高杠杆方式利用PRSU全球定位系统网络进行固体地球变形研究。***

0216626MillerContinuous observations using Global Positioning System (GPS) geodesy yield high-precision determination of horizontal and vertical deformation rates and their variation in time and space. This project builds on the stunning advances that data from the regional Pacific Northwest Geodetic Array (PANGA) has yielded over the last year. In partnership with the surveying community in Puget Sound, PANGA scientists will install a continuous GPS network that is optimally designed to determine the kinematics and locking of the Seattle fault zone, a major fault within the North America plate. In addition, this network provides important new constraints on the periodic recurrence of slow or silent earthquakes, which have been recently discovered along the transition zone of the Cascadia plate interface. Both studies have fundamental importance to characterizing the geodynamics of plate interaction, they also have broader impacts on quantifying seismic strain energy accumulation on a crustal fault that lies in the heart of the urbanized Puget Lowlands. This network will add new constraints to the relative balance between seismic and aseismic strain release mechanisms on the plate boundary fault that is known to generate great earthquakes (approximately magnitude 9) at frequencies of about 500 years. Finally, this project will foster the nascent collaboration between regional professional and academic communities.The Puget Sound surveying community has formed a consortium to support coordination of new GPS technology to the urbanized Puget Lowlands. This collaboration of cities, counties, state agencies, and engineering firms is committed to installing a "virtual reference system" GPS network known as the Puget Reference System Utility (PRSU) that can provide cm-level positioning in real time. Fortuitously, this network is optimal for the earthquake and geodynamics studies outlined above, with the caveat that the solid earth deformation community has the highest standards for monumentation in order that GPS antennas track real earth motion rather than the effects of soil, gourndwater or man-made structures. The Puget Lowlands present the greatest first-order challenges to stable monument design: thick soil horizons, deep sedimentary basins in the foot wall of the Seattle fault and a mantle of debris left behind in the last glacial retreat require use of the deeply anchored drilled braced monument. Such monumentation is thus critical to making geophysically meaningful observations of great precision required by the problems posed here. This project funds geodetic quality monuments in order to leverage the PRSU GPS network for solid earth deformation studies in a highly leveraged fashion. ***