期刊
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
卷 123, 期 7, 页码 6019-6032出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2017JB015160
关键词
East African Rift; magnetotellurics; magma storage
资金
- Natural Environment Research Council (NERC) [NE/L013932/1]
- NERC [NE/L002558/1]
- NERC [NE/L013932/1] Funding Source: UKRI
The Main Ethiopian Rift is part of the East African Rift with its unique geological setting as an active continental breakup zone. The Main Ethiopian Rift includes a number of understudied active volcanoes with potentially high risks for this densely populated part of Ethiopia. Using newly recorded (2016) magnetotelluric data along a 110 km long transect crossing the whole rift, we present a regional 2-D model of electrical resistivity of the crust. The derived model endorses a previous study that drew the surprising conclusion that there was no highly conductive region associated with a magma chamber directly under the central rift volcano Aluto. This has implications for the estimation of the amount of magma present, its water content, and the storage conditions, as the volcano is actively deforming and results from seismicity and CO2 degassing studies all indicate magma storage at about 5 km depth. Additionally, the existence of a strong conductor under the Silti Debre Zeyt Fault Zone approximately 40 km to the northwest of the rift center is confirmed. It is located with a slight offset to the Butajira volcanic field, which hosts a number of scoria cones at the boundary between the NW plateau and the rift. The magnetotelluric model reveals different electrical structures below the eastern and western rift shoulders. The western border is characterized by a sharp lateral contrast between the resistive plateau and the more conductive rift bottom, whereas the eastern flank shows a subhorizontal layered sequence of volcanic deposits and a smooth transition toward the shoulder.
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