首页> 外文期刊>Journal of geophysical research. Solid earth: JGR >Three-dimensional seismic velocity structure of Mauna Loa and Kilauea volcanoes in Hawaii from local seismic tomography
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Three-dimensional seismic velocity structure of Mauna Loa and Kilauea volcanoes in Hawaii from local seismic tomography

机译:基于局部地震层析成像的夏威夷莫纳罗亚火山和基拉韦厄火山三维地震速度结构

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We present a new three-dimensional seismic velocity model of the crustal and upper mantle structure for Mauna Loa and Kilauea volcanoes in Hawaii. Our model is derived from the first-arrival times of the compressional and shear waves from about 53,000 events on and near the Island of Hawaii between 1992 and 2009 recorded by the Hawaiian Volcano Observatory stations. The V_p model generally agrees with previous studies, showing high-velocity anomalies near the calderas and rift zones and low-velocity anomalies in the fault systems. The most significant difference from previous models is in V_p∕V_s structure. The high-V_p and high-V_p∕V_s anomalies below Mauna Loa caldera are interpreted as mafic magmatic cumulates. The observed low-V_p and high-V_p∕V_s bodies in the Kaoiki seismic zone between 5 and 15 km depth are attributed to the underlying volcaniclastic sediments. The high-V_p and moderate- to low-V_p∕V_s anomalies beneath Kilauea caldera can be explained by a combination of different mafic compositions, likely to be olivine-rich gabbro and dunite. The systematically low-V_p and low-V_p∕V_s bodies in the southeast flank of Kilauea may be caused by the presence of volatiles. Another difference between this study and previous ones is the improved V_p model resolution in deeper layers, owing to the inclusion of events with large epicentral distances. The new velocity model is used to relocate the seismicity of Mauna Loa and Kilauea for improved absolute locations and ultimately to develop a high-precision earthquake catalog using waveform cross-correlation data.
机译:我们提出了夏威夷毛纳罗亚火山和基拉韦厄火山的地壳和上地幔结构的新三维地震速度模型。我们的模型是根据1992年至2009年夏威夷岛及附近夏威夷岛及其附近地区约53,000个事件的压缩波和切变波的首次到达时间得出的。 V_p模型总体上与以前的研究一致,显示了破火山口和裂谷带附近的高速异常和断层系统中的低速异常。与以前的模型最大的不同在于V_p ∕ V_s结构。莫纳罗阿火山口以下的高V_p和高V_p ∕ V_s异常被解释为镁铁质岩浆堆积。在5至15 km深度的Kaoiki地震带中观测到的低V_p和高V_p ∕ V_s体归因于下伏的火山碎屑沉积物。基克拉韦火山破火山口下方的高V_p和中低V_p ∕ V_s异常可以用不同的镁铁质成分的组合来解释,这些成分可能是富含橄榄石的辉长岩和榴辉岩。基拉韦厄东南侧的系统性低V_p和低V_p ∕ V_s体可能是由于挥发物的存在所致。这项研究与以前的研究之间的另一个区别是,由于包含了较大的震中距离的事件,因此在更深层中的V_p模型分辨率有所提高。新的速度模型用于重新定位Mauna Loa和Kilauea的地震活动性,以改善绝对位置,并最终使用波形互相关数据来开发高精度地震目录。

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