Characterization of volcanic materials using ground penetrating radar:: A case study at Teide volcano (Canary Islands, Spain)
Characterization of volcanic materials using ground penetrating radar:: A case study at Teide volcano (Canary Islands, Spain)
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DOI：
10.1016/j.jappgeo.2005.07.007
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发表时间：
2006-05-01
影响因子：
2
通讯作者：
Carreno, F.
中科院分区：
文献类型：
--
作者：
Gomez-Ortiz, D.;Martin-Velazquez, S.;Carreno, F.
探地雷达（GPR）是一种有用的地球物理技术，可用于表征地下火山物质的性质、几何形状和空间分布，这些宝贵的数据可用于在从地表获取的信息受到限制的地区完成现场观测。我们分析了泰德火山和拉斯卡哈达斯大厦（西班牙加那利群岛特内里费岛）中出现的几种火山物质（大量非均质熔岩流、pahoehoe 和 aa 熔岩流、空气沉积物和岩堤）的探地雷达响应，以识别它们的出现并表征其厚度、空间分布、内部结构和不连续性，以及评估这些岩石和沉积物中电磁波的平均速度。获得的探地雷达剖面表明，根据材料的性质，反射器的几何形状是独特的。空落浮石的探地雷达反射体很薄、分层良好且横向连续。相比之下，不同的熔岩流以及岩堤会产生不同的雷达响应。当熔岩流中存在交替的块状矿床和矿渣床时，反射器的特征是波状且横向不连续的几何形状。关于帕霍霍熔岩流，它们的雷达特征是由明确的反射器定义的。 AA熔岩流的反射体较弱。大量且均匀的熔岩流和岩堤被解析为内部反射很少或不存在的巨大结构。电磁波穿过不同沉积物的平均速度范围为 0.07 至 0.12 ns(-1)。作为一般近似，电磁波在熔岩流中的速度比在气落沉积物中更快，其中衰减更大且穿透深度更低。电磁波传播速度的估计使我们能够处理剖面并进行深度时间转换和偏移，以获得更真实的二维表示。 (c) 2005 Elsevier B.V. 保留所有权利。
Ground penetrating radar (GPR) is a useful geophysical technique that can be used to characterize the nature, geometry and spatial distribution of subsurface volcanic materials, being these valuable data to complete field observations in those areas where information obtained from the surface is restricted. We have analyzed the GPR response in several volcanic materials (massive and heterogeneous lava flows, pahoehoe and aa lava flows, airfall deposits and a dyke) occurring in the Teide volcano and the Las Cahadas edifice (Tenerife, Canary Islands, Spain), in order to recognize their occurrence and characterize their thickness, spatial distribution, internal structures and discontinuities, as well as to evaluate the mean velocities of the electromagnetic waves in these rocks and deposits. The obtained GPR profiles show that, depending on the nature of the materials, the geometry of the reflectors is distinctive. The GPR reflectors of airfall pumice are thin, well-layered and laterally continuous. In contrast, different lava flows, as well as dykes, originate a different radar response. When alternating massive and scoriaceous beds in lava flows are present, the reflectors are characterized by an undulate and laterally discontinuous geometry. Regarding the pahoehoe lava flows, their radar signature is defined by well defined reflectors. The aa lava flows exhibit weak reflectors. Massive and homogeneous lava flows and dykes are resolved as massive structures with scarce or absent internal reflections. The mean velocity of the electromagnetic waves through the different deposits ranges from 0.07 to 0.12 in ns(-1). As a general approximation, the velocity of the electromagnetic waves is faster in lava flows that in airfall deposits, where attenuation is greater and penetration depth is lower. The estimation of the propagation velocity for the electromagnetic waves has allowed us to process the profiles and to carry out depth-time conversions and migration, in order to get more realistic 2-D representations. (c) 2005 Elsevier B.V. All rights reserved.