4D volcano gravimetry
4D volcano gravimetry
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DOI：
10.1190/1.2977792
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发表时间：
2008-11-01
期刊：
影响因子：
3.3
通讯作者：
Fernandez, Jose
中科院分区：
文献类型：
--
作者：
Battaglia, Maurizio;Gottsmann, Joachim;Fernandez, Jose
与时间相关的重力测量可以在岩浆流导致地震或其他喷发前兆之前很久就探测到地下过程。如果重力测量与地面变形数据进行分析和建模，重力测量检测地下质量流的能力将大大增强。要从微重力研究中获得最大限度的信息，就需要认真评价网络基准的布局、重力环境信号以及重力变化与地壳变形之间的耦合。当所研究的系统变化很快（数小时至数周）时，如在热液系统和不平静的火山中，在选定的地点进行连续的重力观测可以帮助捕获侵入源动态的许多细节。尽管仪器的影响，主要是由大气温度引起的，结果从监测山。埃特纳火山的连续观测表明，连续观测是监测和研究火山的有力工具，几种解析和数值数学模型可以用来拟合重力和形变数据。分析模型提供了一个封闭形式的火山源的描述。原则上，这允许人们容易地推断源参数的相对重要性。在活跃的火山点，如长谷破火山口（加州，美国）和Campi Flegrei（意大利）的研究表明，仔细使用分析模型和高质量的数据集产生了良好的结果。然而，使分析模型易于处理的简化可能导致误导性的火山解释，特别是当震源周围的真实的地壳远离均匀/各向同性假设时。使用数值模型可以更真实地描述震源及其所在地壳（例如，垂直和横向机械不连续性、复杂的震源几何形状和地形）。在泰德火山（特内里费岛）和Campi Flegrei的应用表明，这种更现实的描述在重力计算的重要性。
Time-dependent gravimetric measurements can detect subsurface processes long before magma flow leads to earthquakes or other eruption precursors. The ability of gravity measurements to detect subsurface mass flow is greatly enhanced if gravity measurements are analyzed and modeled with ground-deformation data. Obtaining the maximum information from microgravity studies requires careful evaluation of the layout of network benchmarks, the gravity environmental signal, and the coupling between gravity changes and crustal deformation. When changes in the system under study are fast (hours to weeks), as in hydrothermal systems and restless volcanoes, continuous gravity observations at selected sites can help to capture many details of the dynamics of the intrusive sources. Despite the instrumental effects, mainly caused by atmospheric temperature, results from monitoring at Mt. Etna volcano show that continuous measurements are a powerful tool for monitoring and studying volcanoes.Several analytical and numerical mathematical models can beused to fit gravity and deformation data. Analytical models offer a closed-form description of the volcanic source. In principle, this allows one to readily infer the relative importance of the source parameters. In active volcanic sites such as Long Valley caldera (California, U.S.A.) and Campi Flegrei (Italy), careful use of analytical models and high-quality data sets has produced good results. However, the simplifications that make analytical models tractable might result in misleading volcanological inter-pretations, particularly when the real crust surrounding the source is far from the homogeneous/isotropic assumption. Using numerical models allows consideration of more realistic descriptions of the sources and of the crust where they are located (e.g., vertical and lateral mechanical discontinuities, complex source geometries, and topography). Applications at Teide volcano (Tenerife) and Campi Flegrei demonstrate the importance of this more realistic description in gravity calculations.