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| Titel |
Ocean noise triggering of LP events at Deception Island volcano |
| VerfasserIn |
D. Stich, J. Almendros, V. Jiménez, F. Mancilla, E. Carmona |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066993
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| Zusammenfassung |
| During the austral winter 2009, swarms of long-period (LP) events with astonishingly regular
interevent times were recorded at Deception Island volcano, Antarctica. Swarm events have
similar waveforms, indicating the repeated activation of a non-destructive source process.
These swarms may last up to a few hours, and characteristic inter-event times range from
~10 s to ~20 s for individual swarms. The amplitudes of the periodic LPs vary significantly
over a short time scale, which makes an association with a steady state internal process
complicate. On the other hand, we observe that LP inter-event times are approximate
integer multiples of the dominant periods of the oceanic microseism, and propose
that the periodicity observed in the occurrence times of LP events is the result of
dynamic triggering of the LP source process by the effect of oceanic microtremors. A
positive correlation between microseism amplitude and LP periodicity supports this
idea. We attribute LP periodicity to the coincidence of sustained LP activity in an
unstable hydrothermal system and external forcing by ocean noise that introduces
periodic pressure variations in volcano fluids. We estimate the volumetric strain
change generated by the oceanic microseism at the source location and conclude that
strain of order 10-7 is sufficient to introduce clear periodicity in the LP sequences. |
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