@article{14c39ddf2ba7449f8ecb9a21984dbbe1,
title = "Noise-based passive ballistic wave seismic monitoring on an active volcano",
abstract = "Monitoring temporal changes of volcanic interiors is important to understand magma, fluid pressurization and transport leading to eruptions. Noise-based passive seismic monitoring using coda wave interferometry is a powerful tool to detect and monitor very slight changes in the mechanical properties of volcanic edifices. However, the complexity of coda waves limits our ability to properly image localized changes in seismic properties within volcanic edifices. In this work, we apply a novel passive ballistic wave seismic monitoring approach to examine the active Piton de la Fournaise volcano (La R{\'e}union island). Using noise correlations between two distant dense seismic arrays, we find a 2.4 per cent velocity increase and-0.6 per cent velocity decrease of Rayleigh waves at frequency bands of 0.5-1 and 1-3 Hz, respectively. We also observe a-2.2 per cent velocity decrease of refracted P waves at 550 m depth at the 6-12 Hz band. We interpret the polarity differences of seismic velocity changes at different frequency bands and for different wave types as being due to strain change complexity at depth associated with subtle pressurization of the shallow magma reservoir. Our results show that velocity changes measured using ballistic waves provide complementary information to interpret temporal changes of the seismic properties within volcanic edifices.",
keywords = "Body waves, Seismic interferometry, Surface waves, Wave propagation",
author = "Tomoya Takano and Florent Brenguier and Michel Campillo and Aline Peltier and Takeshi Nishimura",
note = "Funding Information: We acknowledge support from the French ANR grant T-ERC 2018 (FaultProbe), the European Research Council under grants no. 742335, F-IMAGE and no. 817803 FAULTSCAN, and the European Union's Horizon 2020 research and innovation program under grant agreement No. 776622 (PACIFIC). Funding Information: We thank a VolcArray project for providing us the continuous seismic data. VolcArray is a joint project between ISTerre, Observa-toire Volcanologique du Piton de la Fournaise (OVPF), Institut de Physique du Globe de Paris (IPGP) and Parc National de la R{\'e}union. The data are available without restrictions from the RE-SIF and EIDA data centres under the FDSN network code XP (doi:10.15778/RESIF.XP2014). We acknowledge support from the French ANR grant T-ERC 2018 (FaultProbe), the European Research Council under grants no. 742335, F-IMAGE and no. 817803 FAULTSCAN, and the European Union{\textquoteright}s Horizon 2020 research and innovation program under grant agreement No. 776622 (PACIFIC). Tomoya Takano is grateful for support from the Japan Society for the Promotion of Science (JSPS) and the International Joint Graduate Program in Earth and Environmental Sciences (GP-EES). This is IPGP contribution number 4074. We acknowledge P. Bou{\'e}, H. Nakahara and H. Pedersen for useful discussions. We thank Dr Andrea Morelli, Dr Kees Wapenaar, and Dr Laura Ermert for their comments which significantly improved the manuscript. Publisher Copyright: {\textcopyright} 2019 The Author(s). Published by Oxford University Press on behalf of The Royal Astronomical Society.",
year = "2020",
month = jan,
day = "1",
doi = "10.1093/gji/ggz466",
language = "English",
volume = "220",
pages = "501--507",
journal = "Geophysical Journal International",
issn = "0956-540X",
publisher = "Wiley-Blackwell",
number = "1",
}