Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing
Abstract Pre‐eruptive electrical signals at active volcanoes are generally interpreted in terms of electrokinetic processes. Spatio‐temporal self‐potential (SP) signals can be caused by strain‐induced fluid flow in volcanic aquifers, however, previous studies lack the quantitative assessments of the...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-12-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2020GC009388 |
| _version_ | 1827771628636864512 |
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| author | Fee Arens Joachim Gottsmann Karen Strehlow James Hickey Geoff Kilgour |
| author_facet | Fee Arens Joachim Gottsmann Karen Strehlow James Hickey Geoff Kilgour |
| author_sort | Fee Arens |
| collection | DOAJ |
| description | Abstract Pre‐eruptive electrical signals at active volcanoes are generally interpreted in terms of electrokinetic processes. Spatio‐temporal self‐potential (SP) signals can be caused by strain‐induced fluid flow in volcanic aquifers, however, previous studies lack the quantitative assessments of these phenomena and the underpinning poroelastic responses. Here we use Finite‐Element Analysis to study poroelastic responses induced by subsurface stressing from sill and dike sources by jointly solving for ground displacements, pore pressure, and SP signals. We evaluate the influence of pressure source orientation on the poroelastic response in two different volcanic aquifers (pyroclastic and lava flow) to provide insights on emergent geodetic and SP signals and their sensitivity to governing parameters. Strain‐induced SP amplitudes deduced from a reference parameter set vary in both aquifer models and are of negative polarity (−0.35 and −22.6 mV) for a pressurized dike and of positive polarity (+4 and +20 mV) for a pressurized sill. Importantly, we find uniquely different SP and ground displacement patterns from either sill or dike intrusions. Our study shows that SP signals are highly sensitive to the subsurface Young's modulus, streaming potential coupling coefficient and electrical conductivity of the poroelastic domains. For the set of parameters tested, the dike model predicts SP amplitudes of up to −947 mV which are broadly representative of recorded amplitudes from active volcanoes. Our study demonstrates that electrokinetic processes reflect magma‐induced stress and strain variations and highlights the potential of joint geodetic and SP studies to gain new insights on causes of volcanic unrest. |
| first_indexed | 2024-03-11T12:56:55Z |
| format | Article |
| id | doaj.art-d5bcaab41895439ba42c6beb8c28e355 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:56:55Z |
| publishDate | 2020-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-d5bcaab41895439ba42c6beb8c28e3552023-11-03T17:00:40ZengWileyGeochemistry, Geophysics, Geosystems1525-20272020-12-012112n/an/a10.1029/2020GC009388Electrokinetic Contributions to Self‐Potential Signals From Magmatic StressingFee Arens0Joachim Gottsmann1Karen Strehlow2James Hickey3Geoff Kilgour4School of Earth Sciences University of Bristol Bristol UKSchool of Earth Sciences University of Bristol Bristol UKGEOMAR Helmholtz Center for Ocean Research Kiel GermanyCamborne School of Mines University of Exeter Cornwall UKGNS Science Wairakei Research Center Taupo New ZealandAbstract Pre‐eruptive electrical signals at active volcanoes are generally interpreted in terms of electrokinetic processes. Spatio‐temporal self‐potential (SP) signals can be caused by strain‐induced fluid flow in volcanic aquifers, however, previous studies lack the quantitative assessments of these phenomena and the underpinning poroelastic responses. Here we use Finite‐Element Analysis to study poroelastic responses induced by subsurface stressing from sill and dike sources by jointly solving for ground displacements, pore pressure, and SP signals. We evaluate the influence of pressure source orientation on the poroelastic response in two different volcanic aquifers (pyroclastic and lava flow) to provide insights on emergent geodetic and SP signals and their sensitivity to governing parameters. Strain‐induced SP amplitudes deduced from a reference parameter set vary in both aquifer models and are of negative polarity (−0.35 and −22.6 mV) for a pressurized dike and of positive polarity (+4 and +20 mV) for a pressurized sill. Importantly, we find uniquely different SP and ground displacement patterns from either sill or dike intrusions. Our study shows that SP signals are highly sensitive to the subsurface Young's modulus, streaming potential coupling coefficient and electrical conductivity of the poroelastic domains. For the set of parameters tested, the dike model predicts SP amplitudes of up to −947 mV which are broadly representative of recorded amplitudes from active volcanoes. Our study demonstrates that electrokinetic processes reflect magma‐induced stress and strain variations and highlights the potential of joint geodetic and SP studies to gain new insights on causes of volcanic unrest.https://doi.org/10.1029/2020GC009388electrical self‐potential as indicator of volcanic unrestground deformationnumerical modelingporoelasticityvolcanic unrest |
| spellingShingle | Fee Arens Joachim Gottsmann Karen Strehlow James Hickey Geoff Kilgour Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing Geochemistry, Geophysics, Geosystems electrical self‐potential as indicator of volcanic unrest ground deformation numerical modeling poroelasticity volcanic unrest |
| title | Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing |
| title_full | Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing |
| title_fullStr | Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing |
| title_full_unstemmed | Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing |
| title_short | Electrokinetic Contributions to Self‐Potential Signals From Magmatic Stressing |
| title_sort | electrokinetic contributions to self potential signals from magmatic stressing |
| topic | electrical self‐potential as indicator of volcanic unrest ground deformation numerical modeling poroelasticity volcanic unrest |
| url | https://doi.org/10.1029/2020GC009388 |
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