Magmatic Processes in the East African Rift System: Insights From a 2015-2020 Sentinel-1 InSAR Survey
Magmatic Processes in the East African Rift System: Insights From a 2015-2020 Sentinel-1 InSAR Survey
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DOI：
10.1029/2020gc009488
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发表时间：
2021-03-01
影响因子：
3.5
通讯作者：
Biggs, J.
中科院分区：
文献类型：
--
作者：
Albino, F.;Biggs, J.
东非裂谷系统（EARS）由大约78座全新世火山组成，但对它们过去和现在的活动知之甚少。由于缺乏信息，很难了解它们的喷发周期、它们在大陆裂谷中的作用以及它们对人口构成的威胁。虽然以前的干涉合成孔径雷达调查（1990-2010年）显示出动荡的迹象，但由于时间分辨率低和数据集的空白，有关岩浆系统动态的信息仍然有限。哨兵-1号合成孔径雷达使命在非洲每12天提供一次开放获取，并有可能产生长期时间序列，用于研究区域范围内的火山地面变形。在这里，我们使用Sentinel-1数据提供沿着EARS的干涉合成孔径雷达时间序列，为2015-2020年期间。我们在14座火山上探测到18个地面形变信号，其中6座位于阿法尔，6座位于埃塞俄比亚主裂谷，2座位于肯尼亚-坦桑尼亚裂谷。我们在Tullu Moje（2016年）和Suswa（2018年年中）发现了新的隆起事件，并在Gada Ale和Kone发现了神秘的长期沉降信号。沉降信号与多种机制有关，包括岩浆储层的后期演化（例如，Dallafila），熔岩流的压实（例如，Nabro），以及与地热或热液活动有关的孔隙压力变化（例如，Olkaria）。我们的研究结果表明，类似的20%的全新世火山在EARS变形，在这5年的快照，并展示了多样性的过程发生。
The East African Rift System (EARS) is composed of around 78 Holocene volcanoes, but relatively little is known about their past and present activity. This lack of information makes it difficult to understand their eruptive cycles, their roles in continental rifting and the threat they pose to the population. Although previous InSAR surveys (1990-2010) showed sign of unrest, the information about the dynamics of the magmatic systems remained limited by low temporal resolution and gaps in the data set. The Sentinel-1 SAR mission provides open-access acquisitions every 12 days in Africa and has the potential to produce long-duration time series for studying volcanic ground deformation at regional scale. Here, we use Sentinel-1 data to provide InSAR time series along the EARS for the period 2015-2020. We detect 18 ground deformation signals on 14 volcanoes, of which six are located in Afar, six in the Main Ethiopian Rift, and two in the Kenya-Tanzanian Rift. We detected new episodes of uplift at Tullu Moje (2016) and Suswa (mid-2018), and enigmatic long-lived subsidence signals at Gada Ale and Kone. Subsidence signals are related to a variety of mechanisms including the posteruptive evolution of magma reservoirs (e.g., Alu-Dallafila), the compaction of lava flows (e.g., Nabro), and pore-pressure changes related to geothermal or hydrothermal activity (e.g., Olkaria). Our results show that similar to 20% of the Holocene volcanoes in the EARS deformed during this 5-years snapshot and demonstrate the diversity of processes occurring.