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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Surface movements of emplaced lava flows measured by synthetic aperture radar interferometry
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Surface movements of emplaced lava flows measured by synthetic aperture radar interferometry

机译：用合成孔径雷达干涉法测量熔岩流的表面运动

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Lava flows continue to move after they have been emplaced by flow mechanisms. This movement is largely vertical and can be detected using differential synthetic aperture radar (SAR) interferometry, There are three main components to this motion: (1) movement of surface scatterers, resulting in radar phase decorrelation, (2) measurable subsidence of the flow surface due to thermal contraction and clast repacking, and (3) time-dependent depression of the flow substrate. These effects act in proportion to the thickness of the lava flow and decay with time, although there is a time lag before the third component becomes significant. We explore these effects using SAR data from the ERS satellites over the Etna volcano, Sicily. Phase decorrelation on young, thick a'a lava flows persists for a few years and probably results from surface block rotations during flow contraction. Maximum measured subsidence rates of the 1991-1993 lava flow over a period of 70 days are about 0.7 mm day(-1), but are potentially greater in areas of data decorrelation. These rates fall to <2.7 x 10(-2) mm day(-1) after about 20 years in flows about 50 m thick, sooner for thinner flows. Comparison with measured subsidence rates on Kilauean lava lakes suggests that thermal contraction only accounts for about one third of the observed subsidence. The remaining motion is thought to come from surface clast repacking during cooling and from creep mechanisms in the flow substrate. Measurements of postemplacement surface movement provide new constraints on the thermomechanical properties of lava flows and have cautionary implications for the interpretation of interferometric SAR data of volcanoes. [References: 58]
机译：熔岩流在被流动机制放置后继续移动。该运动基本上是垂直的，可以使用差分合成孔径雷达（SAR）干涉测量法检测到。该运动主要包括三个部分：（1）表面散射体的运动，导致雷达相位去相关，（2）流量的可测沉降由于热收缩和碎屑重新堆积而形成的表面，以及（3）随时间流逝的流动基质的凹陷。这些影响与熔岩流的厚度成比例，并随着时间的流逝而衰减，尽管在第三个分量变得重要之前存在时间滞后。我们使用来自西西里岛埃特纳火山上的ERS卫星的SAR数据探索这些影响。年轻，浓稠的a'a熔岩流的相去相关持续了几年，可能是由于流量收缩过程中表面块旋转所致。 1991-1993年熔岩流在70天内的最大测得沉降速率约为0.7毫米日（-1），但在数据解相关方面可能更大。在约50 m厚的流中经过约20年后，这些速率下降到<2.7 x 10（-2）mm·天（-1），对于较薄的流来说更快。与基劳恩斯熔岩湖上的沉降速率的比较表明，热收缩仅占观测到沉降的三分之一。剩余的运动被认为来自冷却过程中表面碎屑的重新包装以及流动基体中的蠕变机制。位移后表面运动的测量为熔岩流的热力学性质提供了新的限制，并且对解释火山的干涉SAR数据具有警示意义。 [参考：58]

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