Broad depth range seismic imaging of the subducted Nazca Slab, North Chile
Broad depth range seismic imaging of the subducted Nazca Slab, North Chile
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智利北部俯冲纳斯卡板块的宽深度范围地震成像
DOI：
10.1016/s0040-1951(02)00117-8
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发表时间：
2002
期刊：
影响因子：
2.9
通讯作者：
M. Yoon
中科院分区：
文献类型：
--
作者：
S. Buske;S. Lüth;H. Meyer;R. Patzig;C. Reichert;S. Shapiro;P. Wigger;M. Yoon
在本文中，我们提出了一个汇编的现代地震和地震学方法，适用于图像的俯冲过程中，在智利北部，南美洲。我们使用的数据从主动和被动地震实验中获得的框架内的德国合作研究中心SFB 267“变形过程在安第斯山脉”。调查区域位于南纬20°至25°之间，从海沟向下延伸至100公里深。在海底和15公里之间的深度范围内，我们使用最近开发的速度模型无关的叠加程序处理海上地震反射剖面。我们发现，在这一深度范围内的俯冲洋岩石圈的上部的特点是地垒-地堑结构。这种结构支撑着板块之间约3公里厚的耦合区。在15 ~ 45 km的深度范围内，分析了1995年安托法加斯塔地震余震的空间分布。余震震源集中在约3公里厚的地层中。最后，在45和100公里之间的深度范围内，我们应用克希霍夫叠前深度偏移陆上ANCORP剖面。在45至60公里深度之间观察到一个双反射带，它可能代表俯冲洋壳的上、下边界。在整个范围下降到超过80-90公里的深度，我们获得的俯冲板片的图像。在该深度，当地地震的震源在垂直于板表面的方向上明显偏离板的反射部分。因此，我们的研究结果产生一个完整的地震图像的下行板块和相关的地震耦合带。
In this paper, we present a compilation of modern seismic and seismological methods applied to image the subduction process in North Chile, South America. We use data from active and passive seismic experiments that were acquired within the framework of the German Collaborative Research Center SFB267 ‘Deformation Processes in the Andes’. The investigation area is located between 20° and 25°S and extends from the trench down to 100 km depth. In the depth range between the sea bottom and 15 km, we process an offshore seismic reflection profile using a recently developed velocity-model-independent stacking procedure. We find that the upper part of the subducting oceanic lithosphere in this depth range is characterized by a horst-and-graben structure. This structure supports an approximately 3 km thick coupling zone between the plates. In the depth range between 15 and 45 km, we analyse the spatial distribution of aftershocks of the Antofagasta earthquake (1995). The aftershock hypocenters are concentrated in an approximately 3 km thick layer. Finally, in the depth range between 45 and 100 km, we apply Kirchhoff prestack depth migration to the onshore ANCORP profile. A double reflection zone is observed between 45 and 60 km depth, which may represent the upper and lower boundary of the subducted oceanic crust. Over the whole range down to more than 80–90 km depth, we obtain an image of the subducting slab. At that depth, the hypocenters of local earthquakes deviate significantly in the direction perpendicular to the slab face from the reflective parts of the slab. Consequently, our results yield a complete seismic image of the downgoing plate and the associated seismic coupling zone.