Spatial relationship between earthquakes and volcanic vents in the central-northern Main Ethiopian Rift
Spatial relationship between earthquakes and volcanic vents in the central-northern Main Ethiopian Rift
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DOI：
10.1016/j.jvolgeores.2013.05.007
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发表时间：
2013-07-15
影响因子：
2.9
通讯作者：
Isola, Ilaria
中科院分区：
文献类型：
--
作者：
Mazzarini, Francesco;Keir, Derek;Isola, Ilaria
在大陆分裂期间，伸展通常由充满流体的裂缝（岩脉）和断层的连接网络来调节。尽管这两个扩展机制的重要性，他们在三维空间的关系是知之甚少，主要是因为它是难以量化的断层和侵入的地下分布。为了解决这个问题，我们进行了定量分析的空间分布和聚类的地震和火山口在东非的主要埃塞俄比亚裂谷，以了解如何通过断层和侵入延伸分布在整个火山裂谷。我们使用地震震中的分形分析，以推断地下断层网络的二维特征，并直接测试我们的模型结果对地震震源的三维分布。研究结果表明，对这些特征进行分形分析是一种可靠的手段，以体现三维性质的断层网络。此外，来自地震的断层网络和来自火山口分形分析的充满岩浆的断裂网络的性质之间的高度相似性强烈表明，这些是遗传联系。然后，我们探索它们的空间联系，使用地震和喷口密度的计算，这表明，地震活动区一般约为20 - 30公里宽，而喷口区较窄，集中在地震活动区。这种空间关系表明，断层，形成裂谷轴向地堑，诱导以上一个狭窄的中心地带的堤防。我们还证明了显着的沿裂谷变化的岩浆活动和断层的程度增加的地区的堤防推断从一个较高的锥密度，其特征在于减少程度的断层。(C)2013爱思唯尔有限公司版权所有。
During the breakup of continents extension is commonly accommodated by connected networks of fluid filled fractures (dykes) and by faults. Despite the importance of these two extension mechanisms their spatial relationship in three dimensions is poorly understood primarily because it is difficult to quantify the subsurface distribution of faulting and intrusion. In order to address this problem, we conduct a quantitative analysis of the spatial distribution and clustering of earthquakes and volcanic vents in the Main Ethiopian Rift in East Africa in order to understand how extension by faulting and intrusion is distributed throughout the volcanic rift. We use fractal analysis of earthquake epicentres in order to infer the 2D characteristics of the subsurface fault network, and directly test our model results against the 3D distribution of earthquake hypocentres. Our results show that fractal analysis of these features is a reliable means to characterise the 3D properties of the fault network. In addition, the strong similarity between the properties of the fault network derived from earthquakes and properties of the magma-filled fracture network derived from fractal analysis of volcanic vents strongly suggests that these are genetically linked. We then explore their spatial link using computation of earthquake and vent density, which shows that the zone of seismicity is generally around 20-30-km-wide, while the zone of vents is narrower and centred within the zone of seismicity. This spatial relationship suggests that the faults, which form rift axial grabens, are induced above a narrower and central zone of diking. We also demonstrate significant along-rift variation in degree of magmatism and faulting with regions of increased degree of diking inferred from a higher cone density characterised by reduced degree of faulting. (C) 2013 Elsevier B.V. All rights reserved.