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首页> 外文期刊>Pure and Applied Geophysics >The 10 April 2014 Nicaraguan Crustal Earthquake: Evidence of Complex Deformation of the Central American Volcanic Arc
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The 10 April 2014 Nicaraguan Crustal Earthquake: Evidence of Complex Deformation of the Central American Volcanic Arc

机译：2014年4月10日尼加拉瓜地壳地震：中美洲火山弧复杂变形的证据

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摘要

On 10 April 2014, an M (w) 6.1 earthquake struck central Nicaragua. The main event and the aftershocks were clearly recorded by the Nicaraguan national seismic network and other regional seismic stations. These crustal earthquakes were strongly felt in central Nicaragua but caused relatively little damage. This is in sharp contrast to the destructive effects of the 1972 earthquake in the capital city of Managua. The differences in damage stem from the fact that the 1972 earthquake occurred on a fault beneath the city; in contrast, the 2014 event lies offshore, under Lake Managua. The distribution of aftershocks of the 2014 event shows two clusters of seismic activity. In the northwestern part of Lake Managua, an alignment of aftershocks suggests a northwest to southeast striking fault, parallel to the volcanic arc. The source mechanism agrees with this right-lateral, strike-slip motion on a plane with the same orientation as the aftershock sequence. For an earthquake of this magnitude, seismic scaling relations between fault length and magnitude predict a sub-surface fault length of approximately 16 km. This length is in good agreement with the extent of the fault defined by the aftershock sequence. A second cluster of aftershocks beneath Apoyeque volcano occurred simultaneously, but spatially separated from the first. There is no clear alignment of the epicenters in this cluster. Nevertheless, the decay of the number of earthquakes beneath Apoyeque as a function of time shows the typical behavior of an aftershock sequence and not of a volcanic swarm. The northeast-southwest striking Tiscapa/Ciudad Jardin and Estadio faults that broke during the 1972 and 1931 Managua earthquakes are orthogonal to the fault where the 10 April earthquake occurred. These orthogonal faults in close geographic proximity show that Central Nicaragua is being deformed in a complex tectonic setting. The Nicaraguan forearc sliver, between the trench and the volcanic arc, moves to the northwest relative to the Caribbean plate at a rate of 14 mm/year. Part of the deformation is apparently accommodated by strain partitioning in the form of bookshelf faulting, on a system of orthogonal faults. The sinistral faults striking northeast-southwest rotate blocks of the Caribbean plate in a clockwise manner. The recent crustal earthquakes in central Nicaragua in 1931, 1972 and 2005 earthquakes took place on these left-lateral faults. The motion of the forearc sliver is also accommodated by a second set of right-lateral, strike-slip faults oriented parallel to the volcanic arc. Faults with this orientation and direction of motion are responsible for the 2014 and possibly the 1955 earthquakes. The presence of this geometry of orthogonal crustal faults highlights the seismic hazard posed by this complex faulting system, not only in the capital city of Managua, but also to the major Nicaraguan cities, which lie close to the volcanic arc.
机译：2014年4月10日，尼加拉瓜中部发生6.1级M级地震。尼加拉瓜国家地震台网和其他区域地震台站清楚地记录了主要事件和余震。在尼加拉瓜中部强烈感受到了这些地壳地震，但造成的破坏相对较小。这与1972年首都马那瓜的破坏性影响形成鲜明对比。破坏的差异源于1972年地震发生在该市下方的断层上。相比之下，2014年的赛事位于马那瓜湖（Lake Managua）下的海上。 2014年地震的余震分布显示了两个地震活动簇。在马那瓜湖西北部，余震排列表明西北向东南走向的断层与火山弧平行。源机制与在与余震序列相同方向的平面上的这种右旋走滑运动相一致。对于这种震级，断层长度和震级之间的地震标度关系表明地下断层长度约为16 km。该长度与余震序列所定义的断层程度非常吻合。阿波耶克火山下方的第二场余震同时发生，但在空间上与第一场分开。在这个簇中震中没有明确的对齐。尽管如此，阿波耶克（Apoyeque）下的地震数量随时间的衰减显示出余震序列的典型行为，而不是火山群的典型行为。东北和西南走向的Tiscapa / Ciudad Jardin和Estadio断裂在1972年和1931年的马那瓜地震中断裂，与4月10日地震发生的断裂正交。这些在地理上接近的正交断层表明尼加拉瓜中部正在复杂的构造环境中变形。在海沟和火山弧之间的尼加拉瓜前臂条以每年14毫米的速度移动到相对于加勒比海板块的西北部。在正交断层系统上，部分变形显然是通过书架断层形式的应变分配来解决的。东北-西南走向的左旋断裂以顺时针方向旋转了加勒比板块。最近的尼加拉瓜中部地壳地震发生在1931年，1972年和2005年，地震发生在这些左侧断裂上。前臂条的运动也被平行于火山弧定向的第二组右旋走滑断层所调节。具有这种运动方向和方向的断层是造成2014年甚至1955年地震的原因。正交地壳断层的这种几何形状的存在突显了这种复杂的断层系统所造成的地震危险，不仅在首都马那瓜，而且还对靠近火山弧的尼加拉瓜主要城市造成了地震。

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