Seismicity of the central Afar rift and implications for Tendaho dam hazards
Seismicity of the central Afar rift and implications for Tendaho dam hazards
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DOI：
10.1144/sp420.9
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
A. Ayele;C. Ebinger;Carolyn van Alstyne;D. Keir;C. Nixon;M. Belachew;J. Hammond
中科院分区：
文献类型：
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作者：
A. Ayele;C. Ebinger;Carolyn van Alstyne;D. Keir;C. Nixon;M. Belachew;J. Hammond
摘要 2007 年至 2011 年在东非裂谷系统阿法尔三重交汇点周围部署的临时宽带地震台网为了解 Tendaho 大坝后面 1.86 km3 蓄水湖系统周围活跃变形地壳的地震活动模式提供了见解。观测到的地震活动与阿法尔中部周围的活跃岩浆中心密切相关。坝址周围地区的特点是北北东向和北西向交叉的断层网络。在指定时间间隔内观测到的地震活动簇表明这两个断层组都是活跃的并且是潜在的地震灾害源。大坝附近自然活跃，将观测到的地震活动与岩浆构造条件的变化联系起来或将其归因于水库荷载的影响是一个挑战。显然，无论活动的起源如何，大坝地区都经历着高水平的地震和火山构造动荡。 S波层析成像模型中观察到的地壳地震活动狭窄区域和上地幔低速区域的空间重叠表明，熔体产生区域引导了大陆破裂期间的应变分布。鉴于其火山和地震活跃的环境，滕达霍坝址及周边地区需要持续监测下游人口的安全和埃塞俄比亚阿法尔国家地区的开发基础设施。
Abstract Temporary broadband seismic networks deployed from 2007 to 2011 around the Afar triple junction of the East African Rift System provide insights into seismicity patterns of the actively deforming crust around the 1.86 km3 impounded lake system behind the Tendaho dam. The observed seismicity correlates well with the active magmatic centres around central Afar. The area around the dam site is characterized by a network of intersecting NNE- and NW-trending faults. Seismicity clusters observed in the specified time interval indicate that both fault sets are active and are potential sources of seismogenic hazards. The dam neighbourhood is naturally active and it is a challenge to associate the observed seismic activity to either a change in magmato-tectonic conditions or attribute it to the influence of reservoir load. It is evident that the dam region experiences high levels of seismic and volcano-tectonic unrest, regardless of the origin of the activity. The spatial overlap of narrow zones of crustal seismicity and upper mantle low velocity zones observed in S-wave tomography models suggests that melt production zones guide the distribution of strain during continental rupture. Given its volcanically and seismically active setting, the Tendaho dam site and the surrounding region require continuous monitoring for the safety of downstream populations and development infrastructures in the Afar National Regional State of Ethiopia.