Dynamics and Detection of Pulsed Tremor at Whakaari (White Island), Aotearoa New Zealand
Volcanic tremor is a crucial indicator for assessing the state and hazard potential of volcanic systems. At Whakaari (White Island volcano, Aotearoa New Zealand), a pulsed tremor signal emerged after a hydrothermal explosion in August 2012. The tremor accompanied the extrusion of a lava dome, before...
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| Published in: | Geophysical research letters Vol. 51; no. 20 |
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| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Washington
John Wiley & Sons, Inc
28-10-2024
Wiley |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Volcanic tremor is a crucial indicator for assessing the state and hazard potential of volcanic systems. At Whakaari (White Island volcano, Aotearoa New Zealand), a pulsed tremor signal emerged after a hydrothermal explosion in August 2012. The tremor accompanied the extrusion of a lava dome, before gradually disappearing prior to the onset of renewed hydrothermal activity in January 2013. We interpret this seismic signal to represent discrete gas transfers from a magmatic intrusion toward a permeable cap—possibly a hydrothermal seal—in the upper layers of Whakaari's hydrothermal system. Such tremor may thus be associated with heightened potential for hazardous explosive activity but is difficult to detect using conventional seismic monitoring parameters. To highlight the emergence of subtle periodic signals, we experiment with Lomb‐Scargle periodograms (LS). LS detect the tremor 5 days before it becomes visible in seismograms, thus facilitating the recognition of such elusive seismic patterns.
Plain Language Summary
A periodic seismic signal was observed at Whakaari (White Island volcano, Aotearoa New Zealand) in 2012, a few weeks after an explosion took place at the volcano. This signal persisted over more than 3 months and consists of slowly emerging, then slowly disappearing and regularly spaced “pulses.” Similar signals have been observed at other volcanic systems, where they are usually linked to rising magma, which then releases gases. Subsequently, gas slugs forming from the magma rise toward the surface and interact with and excite more solid layers of the system, which is visible in the seismic records. Therefore, such seismic signals could indicate increased potential for dangerous volcanic activity. Common techniques applied to track volcano activity struggled to highlight the emergence of this very subtle pattern. Instead, a new visualization approach allowed us to track the emergence and decline of the signal over time. This shows that such subtle patterns can be discovered days before they become recognizable in seismograms. We therefore suggest ongoing testing and validating this approach before adding it to current monitoring techniques. This work helps to identify and better understand the physical processes behind the patterns hidden in the seismic signals of volcanoes.
Key Points
An unusually long‐lasting episode of pulsed tremor was recorded at Whakaari volcano during its 2012/13 eruptive unrest episode
The tremor may reflect discrete gas transfers from a magmatic intrusion toward a permeable cap or sulfuric seal in a hydrothermal system
Subtle, periodic seismic patterns can efficiently be visualized via Lomb‐Scargle periodograms |
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| ISSN: | 0094-8276 1944-8007 |
| DOI: | 10.1029/2024GL110447 |