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首页> 外文期刊>Journal of Volcanology and Geothermal Research2012V243-244NOCT,15 >Local seismicity near the actively deforming Corbetti volcano in the Main Ethiopian Rift
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Local seismicity near the actively deforming Corbetti volcano in the Main Ethiopian Rift

机译：埃塞俄比亚主要裂谷活跃变形的科贝蒂火山附近的局部地震活动

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摘要

Corbetti is currently one of the fastest uplifting volcanoes globally, with strong evidence from geodetic and gravity data for a subsurface inflating magma body. A dense network of 18 stations has been deployed around Corbetti and Hawassa calderas between February 2016 and October 2017, to place seismic constraints on the magmatic, hydrothermal and tectonic processes in the region. We locate 122 events of magnitudes between 0.4 and 4.2 using a new local velocity model. The seismicity is focused in two areas: directly beneath Corbetti caldera and beneath the city of Hawassa. The shallower 0-5 km depth below sea level (b.s.l.) earthquakes beneath Corbetti are mainly focused in EW- to NS-elongated clusters at Urji and Chabbi volcanic centres. This distribution is interpreted to be mainly controlled by a northward propagation of hydrothermal fluids away from a cross-rift pre-existing fault. Source mechanisms are predominantly strike-slip and different to the normal faulting away from the volcano, suggesting a local rotation of the stress-field. These observations, along with a low Vp/Vs ratio, are consistent with the inflation of a gas-rich sill, likely of silicic composition, beneath Corbetti. In contrast, the seismicity beneath Hawassa extends to greater depth (16 km b.s.l.). These earthquakes are focused on 8-10 km long segmented faults, which are active in seismic swarms. One of these swarms, in August 2016, is focused between 5 and 16 km depth b.s.l. along a steep normal fault beneath the city of Hawassa, highlighting the earthquake hazard for the local population. (C) 2019 Elsevier B.V. All rights reserved.
机译：Corbetti目前是全球上升最快的火山之一，地下大岩浆体的大地测量和重力数据提供了有力的证据。 2016年2月至2017年10月之间，在Corbetti和Hawassa火山口周围部署了由18个站组成的密集网络，以对该地区的岩浆，热液和构造过程施加地震约束。我们使用新的局部速度模型定位了0.4至4.2之间的122个事件的数量级。地震活动集中在两个区域：Corbetti破火山口正下方和Hawassa市下方。科尔比蒂以下海平面（b.s.l.）下方0-5公里的浅层地震主要集中于乌尔吉和查比火山中心的EW-NS长的星团。据认为，这种分布主要是由热液向北传播，远离交叉裂谷早已存在的断层所控制。震源机制主要是走滑作用，与正常的断层远离火山，这表明应力场发生了局部旋转。这些观察结果以及较低的Vp / Vs比与Corbetti下方富含气体的基岩（可能为硅质成分）的膨胀一致。相反，哈瓦萨（Hawassa）下方的地震活动范围更大（16 km b.s.l.）。这些地震集中在8-10 km长的分段断层中，这些断层在地震群中活跃。其中一支蜂群于2016年8月聚焦在b.s.l. 5至16 km深度之间。沿哈瓦萨（Hawassa）市下方的陡峭正常断层，突显了当地居民的地震危险。 （C）2019 Elsevier B.V.保留所有权利。

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