Deflation and inflation of a large magma body beneath Uturuncu volcano, Bolivia? Insights from InSAR data, surface lineaments and stress modelling
Deflation and inflation of a large magma body beneath Uturuncu volcano, Bolivia? Insights from InSAR data, surface lineaments and stress modelling
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DOI：
10.1093/gji/ggu080
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发表时间：
2014-07
影响因子：
2.8
通讯作者：
T. Walter;M. Motagh
中科院分区：
文献类型：
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作者：
T. Walter;M. Motagh
安第斯山脉中部大量的火山灰流喷发产物意味着存在主要的岩浆体;然而，这些岩浆体如何在时间和空间上发展和变化尚不清楚。在这项研究中，我们分析了变形活动的Uturuncu火山，西南玻利维亚，从2003年至2009年使用卫星雷达干涉测量（干涉合成孔径雷达）数据集。我们发现，目前的变形强度和模式可以解释为一个加压源，如一个膨胀的平顶岩浆体在地表以下的22 ± 9公里深度。此外，我们研究的光学遥感数据进行线性构造分析，这表明在地理信息系统（GIS），河流和断层的环带环绕火山在径向距离约15公里。使用数值应力模型，我们找到了火山下的岩浆体，并发现线性构造最好的解释是在约18 ± 2公里深度的一个放气平顶岩浆体，这是与干涉合成孔径雷达研究一致。因此，干涉合成孔径雷达和线性构造数据的独立分析都表明，在Uturuncu下方存在一个水平延伸的平顶岩浆体。定位深度与一个突出的地震低速带一致或刚好在其上方。因此，尽管由本文约束的岩浆体引起的变形的迹象不同，但相似的几何形状和相似的位置表明它们是相似的，可能表明岩浆储存区的寿命。
SUMMARY The voluminous ash-flow eruptive products in the Central Andes imply that there are major magma bodies; however, how these magma bodies develop and change in time and space are not understood. In this study, we analyse the deformation activity of the Uturuncu Volcano, SW Bolivia, from 2003 to 2009 using a satellite radar interferometry (InSAR) data set. We find that the strength and the pattern of the present deformation can be explained by a pressurized source, such as an inflating flat-topped magma body at ∼22 ± 9 km depth below the surface. Furthermore, we examine the optical remote sensing data to perform a lineament analysis, which shows in a geographic information system (GIS) that a girdle of river streams and faults encircle the volcano at radial distance of approximately 15 km. Using numerical stress models, we locate a magma body beneath the volcano and find that the lineaments are best explained by a deflating flat-topped magma body at approximately 18 ± 2 km depth, which is consistent with the InSAR study. Thus, both the independent analysis of InSAR and lineament data suggest the presence of a horizontally extended, flat-topped magma body beneath Uturuncu. The location depth is in agreement with, or just above, a prominent seismic low velocity zone. Consequently, although the sign of deformation caused by the herein constrained magma body differs, the similar geometry and similar location suggest them to be similar, possibly indicating longevity of a magma storage region.