Constraints on dike propagation from continuous GPS measurements
Constraints on dike propagation from continuous GPS measurements
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连续 GPS 测量对堤坝传播的限制
DOI：
10.1029/2001jb000229
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发表时间：
2001
影响因子：
--
通讯作者：
P. Cervelli
中科院分区：
文献类型：
--
作者：
P. Segall;P. Cervelli
1997年1月，夏威夷基拉韦厄火山的东裂谷带喷发发生在全球定位系统连续接收器网络内。GPS测量结果揭示了变形的时间历史，在堤防入侵，开始前208小时的爆发。堤坝体积作为时间的函数，估计从GPS数据使用弹性绿色的功能，为均匀的半空间，表明只有三分之二的最终堤坝体积积累之前的喷发和体积变化率随时间的推移而下降。这些意见是不一致的简单模型的堤坝传播，预测加速堤坝体积的喷发时间和很少或没有变化之后。在基拉韦厄峰会的通货紧缩倾斜的变化反映了推断的岩墙体积的历史，这表明岩墙传播的速度是有限的岩浆流入岩墙。耦合岩脉岩浆房系统的一个简单的，集总参数模型表明，倾向于岩脉结束在喷发（而不是侵入）是有利的高初始岩脉压力，挤压应力状态，大，可压缩的岩浆水库，高导电管道连接的岩脉和源水库。比较模型预测所观察到的岩墙体积的历史，喷发侵入岩浆的比例，和通货紧缩的历史，首脑会议岩浆房建议，大部分的岩浆供应到不断增长的岩墙来自附近的喷发源通过高导电导管。解释是复杂的存在多源水库，岩浆泡和冷却，以及空间变化的岩脉正应力。全球定位系统测量了喷发后山顶岩浆房的再膨胀，并伴随着Pu'u O'o熔岩湖水位的上升。对于一个球形的房间，这些数据意味着一个高峰岩浆房的体积为1020立方公里，与最近的估计地震层析成像。连续变形测量可用于成像传播的岩脉的时空演变，并揭示有关火山管道系统的定量信息。
The January 1997 East Rift Zone eruption on Kilauea volcano, Hawaii, occurred within a network of continuous Global Positioning System (GPS) receivers. The GPS measurements reveal the temporal history of deformation during dike intrusion, beginning ∼8 hours prior to the onset of the eruption. The dike volume as a function of time, estimated from the GPS data using elastic Green's functions for a homogeneous half-space, shows that only two thirds of the final dike volume accumulated prior to the eruption and the rate of volume change decreased with time. These observations are inconsistent with simple models of dike propagation, which predict accelerating dike volume up to the time of the eruption and little or no change thereafter. Deflationary tilt changes at Kilauea summit mirror the inferred dike volume history, suggesting that the rate of dike propagation is limited by flow of magma into the dike. A simple, lumped parameter model of a coupled dike magma chamber system shows that the tendency for a dike to end in an eruption (rather than intrusion) is favored by high initial dike pressures, compressional stress states, large, compressible magma reservoirs, and highly conductive conduits linking the dike and source reservoirs. Comparison of model predictions to the observed dike volume history, the ratio of erupted to intruded magma, and the deflationary history of the summit magma chamber suggest that most of the magma supplied to the growing dike came from sources near to the eruption through highly conductive conduits. Interpretation is complicated by the presence of multiple source reservoirs, magma vesiculation and cooling, as well as spatial variations in dike-normal stress. Reinflation of the summit magma chamber following the eruption was measured by GPS and accompanied a rise in the level of the Pu'u O'o lava lake. For a spheroidal chamber these data imply a summit magma chamber volume of ∼20 km3, consistent with recent estimates from seismic tomography. Continuous deformation measurements can be used to image the spatiotemporal evolution of propagating dikes and to reveal quantitative information about the volcanic plumbing systems.