Submarine landslide triggered by eruption recorded by in-situ hydrophone at NW Rota-1 submarine volcano, Mariana Arc (Invited)
Abstract
An expedition to NW Rota-1, Mariana Arc, in March 2010 with R/V Kilo Moana and ROV Jason found that the submarine volcano (summit depth 520 m) was still erupting more or less continuously as has been observed since 2004, In addition, the expedition also discovered that a major landslide had occurred since the last visit in April 2009, demonstrating the dynamic processes of eruption, collapse, and regrowth in the submarine arc environment. The dive observations reveal the responses of the volcano’s magmatic and hydrothermal systems to such a collapse, as well as how the resident chemosynthetic biological community has responded to the event. The morphologic changes from the landslide can be quantified by comparing multibeam bathymetric surveys between 2009 and 2010. The headwall of the slide is now ~100 m north of the former summit ridge where depth changes up to -90 m occurred between surveys. The slide excavated material from the upper southern slope of the volcano to a distance of 3.5 km downslope, and deposited material between 2-8 km from the summit down to at least 2800 m on the volcano flank. The area and volume of slide deposits (positive depth changes) are 7.1 x 106 m2 and 5.3 x 107 m3, respectively, and the maximum thickness is +42 m. The area and volume of material removed by the slide (negative depth changes) are 2.2 x 106 m2 and -4.1 x 107 m3, respectively. We have found no evidence for a local tsunami generated by this event. The changes in morphology near the summit show that the landslide primarily removed loose volcaniclastic deposits that had accumulated near the active eruptive vent, exposing an underlying stock-like core of resistant intrusive rocks and massive lavas at the summit. During March 2010, there were at least 5 active eruptive vents, located along a line 200-m long, that changed between active and inactive day-to-day and even hour-to-hour, suggesting that the near-surface magmatic plumbing system was still reorganizing after the slide. The landslide also had a major impact on the resident chemosynthetic biological community at NW Rota-1, which previously included two species of shrimp in about equal numbers. However, after the landslide, the Alvinocaris shrimp species was almost wiped out, whereas the Opaepele loihi shrimp had thousands of new recruits. One instrument mooring was moved 1 km downslope and buried by the landslide and 2 others were destroyed. A hydrophone mooring deployed ~150 m west of the summit survived and recorded the sounds of eruptive activity since February 2009. After months of continuous, short duration (~1 min) explosions, the landslide event occurred within a 5-6 hr period on 14 August 2009 during a three-day interval of intense, continuous eruption that apparently triggered the landslide. This landslide/eruption acoustic signal was the largest single event during the two years of monitoring. The hydrophone mooring also showed evidence of having impacted the seafloor, possibly due to the strong currents generated by the slide.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.T11E..06C
- Keywords:
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- 8123 TECTONOPHYSICS / Dynamics: seismotectonics;
- 8185 TECTONOPHYSICS / Volcanic arcs;
- 8427 VOLCANOLOGY / Subaqueous volcanism;
- 8428 VOLCANOLOGY / Explosive volcanism