Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat
The July 2008 Vulcanian Explosion at Soufrière Hills Volcano (SHV), Montserrat, was preceded by one of the largest seismic swarms observed since the start of the eruption. We analyse spectral and waveform properties of the earthquakes in this swarm and compare these observations to models of sub-sur...
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| Format: | Journal article |
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American Geophysical Union
2016
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| _version_ | 1826284285582114816 |
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| author | Rodgers, M Smith, P Mather, T Pyle, D |
| author_facet | Rodgers, M Smith, P Mather, T Pyle, D |
| author_sort | Rodgers, M |
| collection | OXFORD |
| description | The July 2008 Vulcanian Explosion at Soufrière Hills Volcano (SHV), Montserrat, was preceded by one of the largest seismic swarms observed since the start of the eruption. We analyse spectral and waveform properties of the earthquakes in this swarm and compare these observations to models of sub-surface volcanic processes. We observe an initial Volcano-Tectonic (VT) swarm, followed by a large LowFrequency (LF) swarm. We observe that the spectral content of LF events changes over time to carry more energy at lower frequencies. This shift to a lower frequency spectral content is concurrent with an increase in LF event rates. Ash-venting occurred a few hours before peak event rate. There was a subsequent increase in the higher frequency energy component of LF events, concurrent with a decrease in event rates. Seismic quiescence occurred in the final seven hours before the Vulcanian Explosion. Our observations of VT seismicity are consistent with a model of decoupled gas ascent prior to magma emplacement. Changes in spectral properties and event rates suggest changes in conduit properties and/or pressure changes during magma ascent and stalling in the few days before the explosion. This interpretation is supported by previous petrological observations. Our analysis of repeating earthquakes suggests that Hybrid and Long-Period (LP) events are part of the same source process and should not be considered separate classifications, at least at SHV. Our analysis highlights the potential of using simple spectral and waveform analysis for understanding changes in the magmatic system during transitions between quiescence and eruption. |
| first_indexed | 2024-03-07T01:11:34Z |
| format | Journal article |
| id | oxford-uuid:8d2f6298-44d9-42c1-a627-682992248537 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T01:11:34Z |
| publishDate | 2016 |
| publisher | American Geophysical Union |
| record_format | dspace |
| spelling | oxford-uuid:8d2f6298-44d9-42c1-a627-6829922485372022-03-26T22:49:36ZQuiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, MontserratJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:8d2f6298-44d9-42c1-a627-682992248537Symplectic Elements at OxfordAmerican Geophysical Union2016Rodgers, MSmith, PMather, TPyle, DThe July 2008 Vulcanian Explosion at Soufrière Hills Volcano (SHV), Montserrat, was preceded by one of the largest seismic swarms observed since the start of the eruption. We analyse spectral and waveform properties of the earthquakes in this swarm and compare these observations to models of sub-surface volcanic processes. We observe an initial Volcano-Tectonic (VT) swarm, followed by a large LowFrequency (LF) swarm. We observe that the spectral content of LF events changes over time to carry more energy at lower frequencies. This shift to a lower frequency spectral content is concurrent with an increase in LF event rates. Ash-venting occurred a few hours before peak event rate. There was a subsequent increase in the higher frequency energy component of LF events, concurrent with a decrease in event rates. Seismic quiescence occurred in the final seven hours before the Vulcanian Explosion. Our observations of VT seismicity are consistent with a model of decoupled gas ascent prior to magma emplacement. Changes in spectral properties and event rates suggest changes in conduit properties and/or pressure changes during magma ascent and stalling in the few days before the explosion. This interpretation is supported by previous petrological observations. Our analysis of repeating earthquakes suggests that Hybrid and Long-Period (LP) events are part of the same source process and should not be considered separate classifications, at least at SHV. Our analysis highlights the potential of using simple spectral and waveform analysis for understanding changes in the magmatic system during transitions between quiescence and eruption. |
| spellingShingle | Rodgers, M Smith, P Mather, T Pyle, D Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title | Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title_full | Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title_fullStr | Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title_full_unstemmed | Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title_short | Quiescent-explosive transitions during dome-forming volcanic eruptions: Using seismicity to probe the volcanic processes leading to the 29 July 2008 Vulcanian Explosion of Soufrière Hills Volcano, Montserrat |
| title_sort | quiescent explosive transitions during dome forming volcanic eruptions using seismicity to probe the volcanic processes leading to the 29 july 2008 vulcanian explosion of soufriere hills volcano montserrat |
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