Characterizing an Active Magma Chamber at South Sister Volcano, Oregon: Constraints From Gravity and GPS Measurements

描述俄勒冈州南姐妹火山活跃岩浆室的特征：来自重力和 GPS 测量的限制

• 批准号: 0439812
• 负责人: Albert Eggers
• 金额: --
• 依托单位: University of Puget Sound
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0439812&HistoricalAwards=false
• 关键词: Characterizing; Active; Magma; Chamber; South

Characterizing an Active Magma Chamber at South Sister Volcano, Oregon: Constraints From Gravity and GPS MeasurementsEAR-0208490PI: Johnson Modeling of InSAR data by the USGS has determined that an uplift of ~0.022 km 3 has developed since approximately 1998 due to an inflation source at 5-7 km depth. This uplift has not been accompanied by seismic activity. A goal of this project is to determine if this uplift is attributable to new magma injection, expansion of an existing magma body, or hydrothermal processes. If magma injection is producing the uplift, then an important second goal will be to characterize the magma chamber. Important questions to be addressed are: 1) does the magma chamber at 5-7 km depth contain only material added within the past few years? 2) what is the volume of the magma? 3) is the magma basic or silicic? 4) what is the gas content of the magma? These questions will be addressed by modeling the proposed gravity measurements. Three years of gravity observations on three radial profiles of the uplift will be completed. Vertical control with leveling and GPS surveys is planned by the USGS and will be available to this project. The siting of stations and survey schedule will be optimized for the characterization and removal of the annual groundwater and soil moisture signal from this data set. Central to modeling of the gravity changes is observing the ratio of gravity change to vertical uplift at monitored sites, which may be interpreted in terms of mass and density change at depth.

描述俄勒冈州南姐妹火山的活动岩浆室：重力和GPS测量的约束条件（PI-0208490）：美国地质勘探局对干涉合成孔径雷达数据进行的约翰逊建模已经确定，由于5-7 km深度的膨胀源，自1998年以来，约有0.022 km 3的隆起。这种隆起并没有伴随着地震活动。该项目的一个目标是确定这种隆起是否可归因于新的岩浆注入、现有岩浆体的扩张或热液过程。如果岩浆注入造成了隆起，那么第二个重要的目标将是描述岩浆房的特征。需要解决的重要问题是：1）5-7公里深处的岩浆房是否只含有过去几年内添加的物质？2)岩浆的体积是多少？3)岩浆是基性的还是碱性的？4)岩浆的气体含量是多少？这些问题将通过模拟拟议的重力测量来解决。将完成对隆起的三个径向剖面的三年重力观测。美国地质勘探局计划通过水准测量和GPS测量进行垂直控制，并将用于本项目。将优化台站选址和调查时间表，以便从这一数据集中确定和去除年度地下水和土壤湿度信号。重力变化建模的核心是观察重力变化与监测点垂直隆起的比率，这可以用深度的质量和密度变化来解释。