Applicability of InSAR to tropical volcanoes: insights from Central America
Applicability of InSAR to tropical volcanoes: insights from Central America
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DOI：
10.1144/sp380.2
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发表时间：
2013-01-01
期刊：
影响因子：
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通讯作者：
Amelung, F.
中科院分区：
文献类型：
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作者：
Ebmeier, S. K.;Biggs, J.;Amelung, F.
测量火山变形是了解火山喷发行为和探测动荡时期火山行为的关键。卫星技术提供了在全球范围内这样做的机会，但是，除了一些值得注意的例外，相对于高纬度地区的火山，热带地区的火山变形研究得不够，本文对中美洲火山弧进行了系统的调查，以研究干涉合成孔径雷达（InSAR）的适用性。到热带的火山可能妨碍干涉合成孔径雷达测量的火山特征包括：（1）密集的植被覆盖;（2）持续的活动;（3）陡峭的斜坡。变形的测量进一步受到与以下因素相关的大气人为因素的抑制：（4）地形起伏的巨大变化。我们提出了一个系统的方法来区分水蒸气文物和真正的变形。我们的数据显示线性关系（c。2厘米/公里）之间的水蒸气文物的大小和火山大厦的高度。对于高海拔火山（例如危地马拉的Fuego，海拔3763米），（海平面以上）的误差在火山建筑物上为4-5厘米，但在较低的地形上（例如尼加拉瓜的马萨亚，海拔635米）误差小于2厘米。例如，阿纳尔，阿蒂特兰和Fuego说明，卫星采集策略，包括上升和下降的轨道是特别重要的研究陡峭的火山。穷人的一致性主要与时间去相关，这是典型的更快，在中美洲南部的万年青阔叶植被占主导地位。土地利用分类是一个更好的预测去相关率比植被指数。不同雷达波长的相干性比较符合预期;高分辨率X波段雷达最适合存在高分辨率数字高程模型（DEM）的地方研究，而L波段波长则是区域调查所必需的。然而，这是第一次，相位相干性和时间，垂直基线，雷达波长和土地利用之间的关系已被量化的规模上的整个火山弧。
Measuring volcano deformation is key to understanding the behaviour of erupting volcanoes and detecting those in periods of unrest. Satellite techniques provide the opportunity to do so on a global scale but, with some notable exceptions, the deformation of volcanoes in the tropics has been understudied relative to those at higher latitudes, largely due to technical difficulties in applying Interferometric Synthetic Aperture Radar (InSAR).We perform a systematic survey of the Central American Volcanic Arc to investigate the applicability of Interferometric Synthetic Aperture Radar (InSAR) to volcanoes in the tropics. Volcano characteristics that may prevent InSAR measurement include: (1) dense vegetation cover; (2) persistent activity; and (3) steep slopes. Measurements of deformation are further inhibited by atmospheric artefacts associated with: (4) large changes in topographical relief. We present a systematic method for distinguishing between water vapour artefacts and true deformation. Our data show a linear relationship (c. 2 cm/km) between the magnitudes of water vapour artefacts and volcano edifice height. For high relief volcanoes (e.g. Fuego, Guatemala, 3763 m a.s.l. (above sea level)) errors are of the order of 4-5 cm across the volcano's edifice but are less than 2 cm for lower relief (e.g. Masaya, Nicaragua, 635 m a.s.l.). Examples such as Arenal, Atitlan and Fuego illustrate that satellite acquisition strategies incorporating ascending and descending tracks are particularly important for studying steep-sided volcanoes.Poor coherence is primarily associated with temporal decorrelation, which is typically more rapid in southern Central America where Evergreen broadleaf vegetation dominates. Land-use classification is a better predictor of decorrelation rate than vegetation index. Comparison of coherence for different radar wavelengths match expectations; high resolution X-band radar is best suited to local studies where high-resolution digital elevation models (DEMs) exist, while L-band wavelengths are necessary for regional surveys. However, this is the first time that relationships between phase coherence and time, perpendicular baseline, radar wavelength, and land use have been quantified on the scale of a whole volcanic arc.