Results of repeated leveling surveys at Newberry Volcano, Oregon, and near Lassen Peak Volcano, California     

Daniel Dzurisin 《Bulletin of Volcanology》1999,61(1-2):83-91

 Personnel from the U.S. Geological Survey's Cascades Volcano Observatory conducted first-order, class-II leveling surveys near Lassen Peak, California, in 1991 and at Newberry Volcano, Oregon, in 1985, 1986, and 1994. Near Lassen Peak no significant vertical displacements had occurred along either of two traverses, 33 and 44 km long, since second-order surveys in 1932 and 1934. At Newberry, however, the 1994 survey suggests that the volcano's summit area had risen as much as 97±22 mm with respect to a third-order survey in 1931. The 1931 and 1994 surveys measured a 37-km-long, east–west traverse across the entire volcano. The 1985 and 1986 surveys, on the other hand, measured only a 9-km-long traverse across the summit caldera with only one benchmark in common with the 1931 survey. Comparison of the 1985, 1986, and 1994 surveys revealed no significant differential displacements inside the caldera. A possible mechanism for uplift during 1931–1994 is injection of approximately 0.06 km³ of magma at a depth of approximately 10 km beneath the volcano's summit. The average magma supply rate of approximately 1×10^–3 km³/year would be generally consistent with the volcano's growth rate averaged over its 600,000-year history (0.7–1.7×10^–3 km³/year). Received: 10 September 1998 / Accepted: 4 December 1998  相似文献   

数字水准仪与光学水准仪对比观测研究     

郭宝震  董亮  刘伟  孙启凯 《震灾防御技术》2015,10(S1):805-810

近年来,在高精度水准测量领域数字水准仪逐渐呈现出取代光学水准仪的趋势。本文通过实际观测实验,对比分析了两类水准仪的优势与不足。结果表明,光学水准仪相对较重,但性能稳定,而数字水准仪轻巧、操作方便,能很好地避免人为读数误差。在实际工作效率上光学水准仪占优,测量精度的稳定性好于数字水准仪。  相似文献   

An inverse dislocation model of surface deformation in western Washington     

David Verdonck   《Tectonophysics》2005,395(3-4):179-191

Active horizontal and vertical deformation in western Washington is modeled using an inverse dislocation model. The modeling technique uses published horizontal crustal velocities, derived from campaign and continuous GPS data, and uplift rates, calculated from repeated historical leveling surveys. The plate interface is represented by both screw and edge dislocations divided into segments. The rate of slip deficit accumulation on each segment is estimated by inverting the surface deformation data using a linear least squares procedure. The model predicts the data well, with an overall RMS residual of 0.85 mm/year. The horizontal residual vectors show no discernable pattern and no significant uniform regional strain and rigid rotations can be identified. The estimated slip deficit accumulation rates suggest that the plate interface is locked in a broad region beneath the coastline and possibly partially locked further downdip. The maximum slip deficit rate was estimated at 32.1±1.9 mm/year or approximately 91% of the plate convergence rate. The partially locked zone appears to be accumulating slip deficit at 8.2±1.9 mm/year.  相似文献   

跨河水准测量的一种新方法     

廖晓和  王炳南  方元洪 《全球定位系统》2002,27(2):28-32

提出了GPS RTK技术在跨河水准测量中的新应用，分析了影响RTK高程实时解算精度的主要因素，RTK技术应用于跨河水准测量的实施原则、成果比较及精度分析，并提出了一些有益的建议。  相似文献   

郯庐断裂带地壳活动新特征   总被引：4，自引：0，他引：4  

薄万举  杨国华 《东北地震研究》1996,12(4):1-10

在多期大面积水准复测资料分析结果的基础上，结合最新复测资料，并首次结合苏鲁皖三省的跨断层流动水量资料和郯庐带地震台的形变监测资料进行了全时空地、系统地分析、给出了全部有异常活动并去掉长趋势线性项的观测值曲线。  相似文献