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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations
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Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observations

机译：阿拉斯加奥克莫克火山的合成孔径雷达干涉测量法：雷达观测

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ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preeruptive inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs. We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16 months before the eruption and 5 months after the eruption, was preceded by similar to 18 cm of uplift between 1992 and 1995 centered in the same location, and was followed by similar to 10 cm of uplift between September 1997 and 1998. The best fitting model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was similar to 5 km from the eruptive vent. We estimated the volume of the erupted material to be 0.055 km(3) and the average thickness of the erupted lava to be similar to 7.4 m. [References: 38]
机译：ERS-1 / ERS-2合成孔径雷达干涉仪用于研究1997年阿拉斯加Okmok火山的喷发。首先，我们使用串联ERS-1 / ERS-2图像对和预先存在的DEM得出了精确的数字高程模型（DEM）。其次，通过研究干涉相干性的变化，我们发现新喷发的熔岩在喷发后的5-17个月内失去了雷达相干性。这表明表面反向散射特性发生了变化，可能与冷却和压实过程有关。第三，定量评估形变干涉图中的大气延迟异常。在某些干涉图中，大气延迟异常非常明显，并且始终小于一到两个条纹。因此，重复观察对于自信地解释与火山活动有关的小型地球物理信号非常重要。最后，我们使用两遍差分干涉测量法，分析了术前膨胀，矫正放气和后继膨胀，并使用独立的图像对确认了观察结果。我们观察到与1997年喷发有关的沉降超过140厘米。这种沉陷发生在喷发前的16个月至喷发后的5个月之间，在1992年至1995年之间，以同一位置为中心出现了大约18 cm的隆起，然后在1997年9月至1998年之间出现了类似的10 cm隆起。最佳拟合模型表明，岩浆储层位于火山口中心下方2.7 km处，与火山喷口相距5 km。我们估计喷发物质的体积为0.055 km（3），喷发熔岩的平均厚度约为7.4 m。 [参考：38]

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