Pulses of deformation reveal frequently recurring shallow magmatic activity beneath the Main Ethiopian Rift
Pulses of deformation reveal frequently recurring shallow magmatic activity beneath the Main Ethiopian Rift
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DOI：
10.1029/2011gc003662
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发表时间：
2011-09-10
影响因子：
3.5
通讯作者：
Lewi, E.
中科院分区：
文献类型：
--
作者：
Biggs, J.;Bastow, I. D.;Lewi, E.
岩浆活动强烈影响大陆裂谷的发展，但机制，分布和时间尺度熔体侵位和爆发通过地壳浅部没有很好的特点。埃塞俄比亚主裂谷（MER）经历了显著的火山活动，其下的地幔以高温和部分熔融为特征。尽管有丰富的岩浆地质记录，但历史上只有一次喷发记录，而且没有专门的监测网络。因此，该地区目前的岩浆过程仍然缺乏记录，相关的危害被忽视。我们使用基于卫星的干涉合成孔径雷达观测，以证明显着的变形发生在四个火山大厦在MER（Almartu，Corbetti，Bora和Haledebi）从1993年至2010年。这使东非已知正在变形的火山数量超过12座，与许多俯冲弧相当，尽管记录的火山喷发数量较少。最大的位移发生在一个地热发电厂所在地的Alzentu火山，该火山在2004年和2008年出现了两次快速膨胀（10-15厘米），中间是逐渐下沉。我们的观察表明，一个浅（< 10公里），经常补充的岩浆储存区与火山机构，并增加了越来越多的观察表明，浅岩浆过程的操作在十年的时间尺度是无处不在的整个东非裂谷。在没有详细的火山活动历史记录的情况下，基于卫星的变形等监测参数观测可在评估火山灾害方面发挥重要作用。
Magmatism strongly influences continental rift development, yet the mechanism, distribution, and timescales on which melt is emplaced and erupted through the shallow crust are not well characterized. The Main Ethiopian Rift (MER) has experienced significant volcanism, and the mantle beneath is characterized by high temperatures and partial melt. Despite its magma-rich geological record, only one eruption has been historically recorded, and no dedicated monitoring networks exist. Consequently, the present-day magmatic processes in the region remain poorly documented, and the associated hazards are neglected. We use satellite-based interferometric synthetic aperture radar observations to demonstrate that significant deformation has occurring at four volcanic edifices in the MER (Alutu, Corbetti, Bora, and Haledebi) from 1993 to 2010. This raises the number of volcanoes known to be deforming in East Africa beyond 12, comparable to many subduction arcs despite the smaller number of recorded eruptions. The largest displacements are at Alutu volcano, the site of a geothermal plant, which showed two pulses of rapid inflation (10-15 cm) in 2004 and 2008 separated by gradual subsidence. Our observations indicate a shallow (< 10 km), frequently replenished zone of magma storage associated with volcanic edifices and add to the growing body of observations that indicate shallow magmatic processes operating on a decadal timescale are ubiquitous throughout the East African Rift. In the absence of detailed historical records of volcanic activity, satellite-based observations of monitoring parameters, such as deformation, could play an important role in assessing volcanic hazard.