Imaging fluid-related subduction processes beneath Central Java (Indonesia) using seismic attenuation tomography
Imaging fluid-related subduction processes beneath Central Java (Indonesia) using seismic attenuation tomography
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DOI：
10.1016/j.tecto.2013.01.021
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发表时间：
2013-04-01
期刊：
影响因子：
2.9
通讯作者：
Asch, Guenter
中科院分区：
文献类型：
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作者：
Bohm, Mirjam;Haberland, Christian;Asch, Guenter
我们利用两栖临时地震台阵观测到的当地地震资料，推导出爪哇中部地壳和上地幔的地震衰减(Q(P))的空间变化。用频谱反演技术计算了84个本地地震的高质量子集的路径平均衰减值(t*)。通过最小二乘层析反演得到的这些1929个t*值得到了比衰减(Q(P))的3D分布。通过对模型分辨矩阵的分析和综合回收试验，考察了Q(P)模型的置信度。我们注意到现代火山弧下方和以北有一个显著的衰减区，深度达15公里。这些异常大部分似乎与始新世-中新世垦登盆地有关(主要在研究区东部)。在最近火山直接附近的上地壳也发现了增强的衰减，指向中到上地壳部分熔融、存在流体和温度升高的区域。中地壳和下地壳似乎与强烈的加热和整个弧形熔体的存在无关。海洋前弧下俯冲板块上方的衰减增强似乎是由于流体的存在。(C)2013爱思唯尔B.V.保留所有权利。
We use local earthquake data observed by the amphibious, temporary seismic MERAMEX array to derive spatial variations of seismic attenuation (Q(p)) in the crust and upper mantle beneath Central Java. The path-averaged attenuation values (t*) of a high quality subset of 84 local earthquakes were calculated by a spectral inversion technique. These 1929 t*-values inverted by a least-squares tomographic inversion yield the 3D distribution of the specific attenuation (Q(p)). Analysis of the model resolution matrix and synthetic recovery tests were used to investigate the confidence of the Q(p)-model. We notice a prominent zone of increased attenuation beneath and north of the modern volcanic arc at depths down to 15 km. Most of this anomaly seems to be related to the Eocene-Miocene Kendeng Basin (mainly in the eastern part of the study area). Enhanced attenuation is also found in the upper crust in the direct vicinity of recent volcanoes pointing towards zones of partial melts, presence of fluids and increased temperatures in the middle to upper crust. The middle and lower crust seems not to be associated with strong heating and the presence of melts throughout the arc. Enhanced attenuation above the subducting slab beneath the marine forearc seems to be due to the presence of fluids. (C) 2013 Elsevier B.V. All rights reserved.