Self-potential anomaly of Satsuma-Iwojima volcano

Abstract

We conducted self-potential (SP) surveys twice at Satsuma-Iwojima volcano where an intense fumarolic activity continued for more than 1000 years from a summit crater of Iwodake, a lava dome of rhyolite. A positive anomaly of 200 ∼ 250 mV was detected on the Iwodake edifice, although the survey area was limited because of the steep topography and existence of high temperature fumaroles. The anomaly seems to be centered at the summit crater of Iwodake and can roughly be explained by a pair of conduction current source and sink located around the sea level beneath the summit crater. Depth of the current source might indicate the upper end of a liquid-phase water upflow zone, where the liquid-phase water vaporizes due to heat and depressurization. The above model does not explain the additional positive SP anomaly around the summit crater and on the western flank. The anomaly around the summit might be caused by suppression of meteoric water downflow by high temperature volcanic gases. The positive anomaly on the western flank might be caused by local fluid upflows associated with fumaroles on the flank.

Groundwater flow and hydrothermal systems within volcanic edifices: Delineation by electric self‐potential and magnetotellurics

“…In contrast to conventional thought that upward hydrothermal flow significantly contribute to the generation of relatively positive SP zone [ Ishido and Mizutani , 1981; Zlotnicki et al , 1998, 2003; Lénat et al , 2000; Kanda and Mori , 2002; Finizola et al , 2002, 2004, 2006; Zlotnicki and Nishida , 2003; Revil et al , 2004; Aizawa et al , 2005; Hase et al , 2005; Bedrosian et al , 2007; Revil et al , 2008], the SP pattern is relatively insensitive to the hydrothermal upwelling in this model. Because the hydrothermal water has a low ability to transport the electric current owing to its low pH and/or high salinity [ Ishido and Mizutani , 1981; Aizawa , 2008], remarkable SP sources are not generated even when strong hydrothermal upwelling exists.…”

A large self‐potential anomaly and its changes on the quiet Mt. Fuji, Japan

“…Self‐potential (SP) is a natural electrical potential existing within the earth which does not arise from electromagnetically induction or man‐made causes. On an upwelling fluid flow zone, such as an active crater or eruptive fissure, positive charges are accumulated due to electrokinetic effect, and SP anomalies of positive polarity are frequently observed [e.g., Zablocki , 1976; Anderson and Johnson , 1976; Hashimoto and Tanaka , 1995; Sasai et al , 1997; Michel and Zlotnicki , 1998; Kanda and Mori , 2002]. SP anomalies provide information about subsurface hydrothermal system, but the SP distributions on a quiet volcano with no geothermal manifestation are rarely reported.…”

ζ potential measurement of volcanic rocks from Aso caldera

“…Self‐potential (SP) method has been widely utilized in volcanic and geothermal areas since it was successfully applied to Kilauea by Zablocki [1976]. Recently SP method was applied to volcanic areas to investigate subsurface hydrology (e.g., hydrothermal systems) [e.g., Aubert and Atangana , 1996; Zlotnicki et al , 1998; Lénat et al , 2000; Kanda and Mori , 2002; Finizola et al , 2003] and to infer temporal evolution and/or decline of hydrothermal systems associated with volcanic activity [e.g., Hashimoto and Tanaka , 1995; Ishido et al , 1997; Sasai et al , 2002]. A physical basis of these studies is the streaming potential that arises from fluid flow in a porous medium.…”