Self‐potential and magnetic surveying of La Fournaise volcano (Réunion Island): Correlations with faulting, fluid circulation, and eruption

Michel, Sylvie; Zlotnicki, J.

doi:10.1029/98jb00607

Cited by 85 publications

(73 citation statements)

References 30 publications

(15 reference statements)

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“…Self-potential (SP) surveys have been conducted in many volcanoes of subduction zones (e.g., Nishida and Tomiya, 1987;Sasai et al, 1997;Di Maio et al, 1998) as well as of hotspots (e.g., Zablocki, 1976;Michel and Zlotnicki, 1998). A positive sense anomaly of about a few hundreds to more than a thousand millivolts was detected on most of those volcanoes.…”

Section: Introductionmentioning

confidence: 99%

Self-potential anomaly of Satsuma-Iwojima volcano

Kanda

Mori

2014

Earth Planet Sp

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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.

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Section: Introductionmentioning

confidence: 99%

Self-potential anomaly of Satsuma-Iwojima volcano

Kanda

Mori

2014

Earth Planet Sp

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“…Among these signals, time and space electromagnetic disturbances of relatively high amplitudes (several tens of nanotesla for the magnetic field and several hundreds of millivolts for the electrical potential) have been clearly evidenced in a substantial number of field studies and correlated with volcanic activity [Johnston and Stacey, 1969;Zlotnicki and Le Mouël, 1988;Sasai et al, 1990;Tanaka, 1993;Di Maio and Patella, 1994;Hashimoto and Tanaka, 1995;Malengreau et al, 1994;Del Negro et al, 1997;Di Maio et al, 1996Michel and Zlotnicki, 1998]. …”

Section: Introductionmentioning

confidence: 99%

The volcano‐electric effect

2003

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[1] The formation of a magmatic intrusion at depth is responsible for the formation of various thermohydromechanical (THM) disturbances including the upsurge of shock waves and diffusion of pressure fronts in the volcanic system. We couple electromagnetic theory (Maxwell equations) and thermoporoelasticity (Biot equations) to look at the ground surface electrical signature of these THM disturbances. The nature of this coupling is electrokinetic, i.e., associated with water flow relative to the mineral framework and the drag of the excess of charge located in the vicinity of the pore water/mineral interface (the groundwater flow disturbance being related here to the THM disturbances in drained conditions). A new set of laboratory data shows that the electrokinetic coupling is very substantial in fractured basaltic and volcaniclastic materials, and in scoria with several hundreds of millivolts of electrical potential gradient produced per megapascal of pore fluid pressure variations. Our theoretical analysis predicts the diffusion of electromagnetic disturbances and quasi-static electrical signals. These signals can be used as precursors of a volcanic eruption. Indeed, electromagnetic phenomena recorded at the ground surface of a volcanic system, once properly filtered to remove external contributions, provide a direct and quasi-instantaneous insight into the THM disturbances occurring in the heart of the volcanic structure prior and during a volcanic event. Tomography of the quasi-static electrical field is discussed and applied to self-potential profiles performed at the Piton de la Fournaise volcano during the preparation phase of the March 1998 eruption.

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“…Modified from Michel and Zlotnicki (1998). However, surprisingly, SP amplitudes as high as 3 V are observed between the periphery and the terminal cone (Michel and Zlotnicki, 1998;Barde-Cabusson et al, 2012) (Fig.…”

Section: Introductionmentioning

confidence: 92%

“…SP anomalies have been observed on active volcanoes with an amplitude ranging from a few hundreds millivolts up to several volts (Michel and Zlotnicki, 1998;Finizola et al, 2004;Aizawa, 2008;Barde-Cabusson et al, 2012;Brothelande et al, 2014). Saturated ground water flow is usually considered as the main process (so-called electrokinetic phenomenon) inducing the SP signal (Malengreau et al, 1994;Michel, 1998;Aubert et al, 2000;Finizola et al, 2004;Ishido, 2004;Bedrosian et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…In particular, it allows specification of the value of the electrokinetic coupling coefficient relating the convective field to the SP field C. Finally, using the derived value of C, we estimate the SP anomaly that is generated by the humid air convective flow developing within the whole unsaturated layers of the volcano. It is proposed that subsurface humid air convection may explain the SP anomaly observed over the entire volcano (Michel and Zlotnicki, 1998; Barde-Cabusson et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Electric potential anomaly induced by humid air convection within Piton de La Fournaise volcano, La Réunion Island

et al. 2017

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a b s t r a c tSelf potential (SP) anomalies over Piton de La Fournaise volcano (La Réunion Island) are generally inter-preted as resulting from meteoritic water porous flow. However, there is no clear evidence that the subsurface is permanently saturated. Recently, a convective subsurface airflow has been evidenced within a quiescent cone at Piton de La Fournaise (Formica Leo). SP and thermal anomalies are reported on the unsaturated edifice and are seen to be correlated. It is proposed that the SP signal is generated by the movement of water films present on the porous matrix, induced by the intense humid airflow within Formica Leo. The structure of the cone, determined from electrical resistivity tomography (ERT), ground penetrating radar (GPR), microgravimetric and kinematic GPS data, is used to constrain a 3D numerical model of the air convection. The calculated temperature is then used to derive the related SP signal, the electrokinetic coupling coefficient being estimated from direct observations of the electrical resistivity of the soil. Extrapolating these results to the scale of the volcano, it is thus proposed that a cold humid air-flow enters the flanks of the 400 m-high terminal dome, flows up along the sloped and stratified volcanic layers before exiting through the vertical fractures around the Dolomieu collapse. It is demonstrated that the SP anomalies catches the main features recovered over the entire volcano. This result strongly sug-gests that humid airflow may play a major role on the generation of SP anomalies at Piton de la Fournaise volcano, and perhaps in other unsaturated volcanic edifices.

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Self‐potential and magnetic surveying of La Fournaise volcano (Réunion Island): Correlations with faulting, fluid circulation, and eruption

Cited by 85 publications

References 30 publications

Self-potential anomaly of Satsuma-Iwojima volcano

Self-potential anomaly of Satsuma-Iwojima volcano

The volcano‐electric effect

Electric potential anomaly induced by humid air convection within Piton de La Fournaise volcano, La Réunion Island

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