3-D surface wave tomography of the Piton de la Fournaise volcano using seismic noise correlations

• Published in: Geophysical research letters Vol. 34; no. 2; pp. L02305 - n/a
• Main Authors: Brenguier, Florent, Shapiro, Nikolai M., Campillo, Michel, Nercessian, Alexandre, Ferrazzini, Valérie
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.01.2007; Blackwell Publishing Ltd
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Marine; Remote sensing of volcanoes; Sciences of the Universe; seismic noise; Seismology; surface wave tomography; Surface waves and free oscillations; Tomography; Volcano monitoring; Volcano seismology; volcanoes; Volcanology; Piton des Neiges; Piton de la Fournaise; Indian Ocean Islands; Mascarene Islands; Reunion Island; Mascarene Is., Reunion, Pitons des Neiges Volcano; ISW, Indian Ocean, Mascarene Is., Reunion, Piton de la Fournaise Volcano; volcanoes; surface wave tomography; seismic noise; models; orientation; cross-correlation; Indian Ocean; maps; Rayleigh waves; S-waves; magmas; anomalies; Velocity dispersion; observatories; surface waves; tomography; signal-to-noise ratio; noise; calderas; group velocity; rift zones; Wave velocity; waveforms; injection; sea level
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2006GL028586

We invert Rayleigh waves reconstructed from cross‐correlations of 18 months of ambient seismic noise recorded by permanent seismological stations run by the Piton de la Fournaise Volcanological Observatory. By correlating noise records between 21 receivers, we reconstruct Rayleigh waves with sufficient signal‐to‐noise ratio for 210 inter‐station paths. We use the reconstructed waveforms to measure group velocity dispersion curves at periods between 1.5 and 4.5 s. The obtained measurements are inverted for two‐dimensional group velocity maps and finally for a 3‐D S‐wave velocity model of the edifice from +2 to −1 km above sea level. Our results clearly show a high velocity body spatially delimited by the borders of the active 10 km wide caldera. The preferential N30°‐N130° orientations of this anomaly at −0.5 km below sea‐level is an evidence of the preferential paths of magma injections associated to the NE‐SE Rift Zones. This structure is surrounded by a low‐velocity ring interpreted as effusive products associated to the construction of the Piton de la Fournaise volcano on the flank of the older Piton des Neiges volcano.