Low-frequency earthquakes beneath Tullu Moye volcano, Ethiopia, reveal fluid pulses from shallow magma chamber
Low-frequency earthquakes beneath Tullu Moye volcano, Ethiopia, reveal fluid pulses from shallow magma chamber
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埃塞俄比亚图鲁莫耶火山下方的低频地震揭示了浅层岩浆室的流体脉冲
DOI：
10.1016/j.epsl.2019.115782
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发表时间：
2019
影响因子：
5.3
通讯作者：
Greenfield T
中科院分区：
文献类型：
--
作者：
Greenfield T
人们对大陆裂谷中火山下活跃的岩浆过程知之甚少。例如，直到最近，在东非裂谷（EAR），大多数年轻的火山被认为是不活跃的。最近的研究表明，东太平洋地区的许多火山都是地震活跃的，并且正在迅速变形。然而，在浅层岩浆体中存在的积极脱气岩浆的明确迹象一直困扰着大多数研究人员。在这里，我们详细分析了在埃塞俄比亚主裂谷观测到的第一次低频（LF）地震群。这些地震位于图鲁莫耶火山下方，与具有高流体含量的浅层岩浆体的存在直接相关。利用频谱模型，我们表明，LF地震似乎具有低应力降（1-50千帕），我们用低破裂速度和高孔隙流体压力来解释这一点。仔细地重新定位LF地震，将它们置于地表以下约4公里处，属于两个可能的地震群之一。然而，对地震波形之间的相关性分析表明，每一群地震都包含一系列地震科，因此也包含多种震源机制。为了解释这些观测结果，我们提出地震活动是由浅层岩浆体进入高度断裂区域的H2O/ co2流体脉冲引起的。流体脉冲导致高孔隙流体压力，这也导致低破裂速度。
The active magmatic processes beneath volcanoes in continental rifts is poorly understood. For example, until recently in the East African rift (EAR), the majority of the young volcanoes were thought to be inactive. More recent studies have shown that numerous volcanoes in the EAR are seismically active and deforming rapidly. However, an unambiguous sign of actively degassing magma hosted in shallow magma bodies has eluded most investigators. Here we present detailed analysis of the first low-frequency (LF) earthquake swarms to be observed in the Main Ethiopian Rift. The earthquakes locate to beneath Tullu Moye volcano and are directly related to the presence of a shallow magma body with a high fluid content. Using spectral modelling we show that the LF earthquakes appear to have low stress-drops (1–50 kPa) which we interpret in terms of low rupture velocities and high pore-fluid pressure. Careful relocation of the LF earthquakes place them approximately 4 km below the surface within one of two possible clusters. However, analysis of the correlation between earthquake waveforms show that each swarm contains a range of earthquake families and as such a diversity of earthquake source mechanisms. To explain these observations, we propose the seismicity is induced by H2O/CO2fluid pulses from the shallow magma body into a highly fractured region. Fluid pulses cause high pore fluid pressures, which also cause the low rupture velocities.
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影响因子：
2.4
作者：
G. Corti;M. Philippon;F. Sani;D. Keir;T. Kidane
通讯作者：
G. Corti;M. Philippon;F. Sani;D. Keir;T. Kidane
埃塞俄比亚裂谷系统的横流断层
影响因子：
64.8
作者：
P. Mohr
通讯作者：
P. Mohr
影响因子：
5.2
作者：
F. Samrock;A. Grayver;H. Eysteinsson;M. Saar
通讯作者：
F. Samrock;A. Grayver;H. Eysteinsson;M. Saar
影响因子：
64.8
作者：
Iverson, Richard M.;Dzurisin, Daniel;Vallance, James W.
通讯作者：
Vallance, James W.
DOI：
10.1029/jb093ib05p04375
发表时间：
1988-05-10
期刊：
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS
影响因子：
--
作者：
CHOUET, B
通讯作者：
CHOUET, B