Hydrothermal system mapped by CSAMT on Karthala volcano, Grande Comore Island, Indian Ocean

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• 作者：Savin ; Cé ; cile ; Ritz ; Michel ; Join ; Jean-Lambert ; Bachelery ; Patrick
• 关键词：Karthala volcano ; CSAMT method ; Resistivity structure ; Hydrothermal system
• 刊名：Journal of Applied Geophysics
• 出版年：2001
• 出版时间：October, 2001
• 年：2001
• 卷：48
• 期：3
• 页码：143-152
• 全文大小：484 K

文摘

Controlled source audio-magnetotelluric (CSAMT) has been used to investigate the resistivity structure of the summit region of Karthala volcano. The major purpose of this CSAMT survey is to locate the active hydrothermal system. The presence of the hydrothermal system had already been inferred from surface evidence of hydrothermal activity and from self-potential (SP) mapping of the Karthala summit zone. The results of the 1D CSAMT inversion indicate the following: (1) a highly resistive (500–5000 Ω m) 200- to 400-m thick surface layer, that is characteristic of dry basaltic rocks, and made up of lava flows and/or tuff breccias; (2) a 300- to 1200-m thick layer of intermediate resistivity (20–400 Ω m), thought to be representative of the groundwater body; and (3) a deep conductor with a resistivity of less than 2 Ω m, which might be related to the active hydrothermal system.