Preliminary Insights Into the Seismicity Related to the Strombolian Explosions of Yasur Volcano (Vanuatu)
Abstract
Since January 2008, we operate a temporary seismic network around Yasur volcano, a permanently active strombolian volcano located on the island of Tanna, Vanuatu. The network includes up to 22 stations with 10 3-component broad-band stations equipped with 30 s Guralp sensors and 12 seismic antennas each including up to nine short period components. Since the installation of the network, the activity of the volcano is at a relatively high level with commonly several explosions per minute. The network records an intense seismic activity with thousands of transients per day. A strong very long period seismicity below 1 Hz is also observed. Video recordings indicate that most of the high frequency transients are directly related to the strombolian explosions. They also outline the presence of fewer signals who are not accompanied by any surface activity. The explosion quakes have a spectral content dominated by frequencies below 4-5 Hz with most of the time short higher frequency acoustic phases. A large amount of the events exhibits a high degree of waveform similarity. By scanning the 5 months of continuous data available until now with several pre- defined master events, we identified the presence of several well defined families of events that dominate the activity. This result suggests the explosive activity is characterized by the presence of dominant modes of resonance of the conduit in response to the gas slug ascents causing the explosions. These modes were apparently affected by the occurrence of a M=7.3 earthquake on April 9 about 50 km offshore of the island. While the earthquake did not significantly change the surface morphology of the volcano nor the intensity of the eruptive activity, it apparently caused significant changes to the resonance of the conduit as no similar family of explosion quakes is observed both before and after the earthquake.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.V51E2087B
- Keywords:
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- 8404 Volcanoclastic deposits;
- 8414 Eruption mechanisms and flow emplacement;
- 8419 Volcano monitoring (7280);
- 8428 Explosive volcanism;
- 8445 Experimental volcanism