First Results from the UnderVolc High Resolution Seismic and GPS Network Deployed on Piton de la Fournaise Volcano

Recent advances in volcano seismology such as the measurement from seismic noise of subtle decreases of seismic velocities preceding volcanic eruptions (Brenguier et al. 2008; Duputel et al. 2009) or the precise localization of volcano-hydrothermal microseismic tremor sources (Taisne et al. 2011; Cros et al. 2011) have emerged from the analysis of long-term, continuous, and high-quality seismic data. There is thus an increasing need for high-resolution continuous seismic data in volcanic environments to improve our knowledge of fundamental volcanic processes such as deep magma transfers, volcanic unrest, magma transport, and eruptions. With 30 eruptions since 2000, Piton de la Fournaise volcano (La Reunion Island) has been among the most active volcanoes worldwide. This volcano emits basaltic lavas with volumes ranging from less than 1 million cubic meters to hundreds of millions of cubic meters. Piton de la Fournaise volcano has been monitored since 1979 from a permanent observatory that since 1999 has recorded continuous seismic and deformation data. Since 2009, we have deployed new broadband seismic and GPS stations under the framework of the UnderVolc research project. Most of the temporary stations are being converted to permanent stations, and the continuous seismic waveforms are publicly available by standard netdc requests. Within this paper, we will provide technical information about the deployed UnderVolc broadband seismic and GPS stations. We will also present data quality measurements from a noise spectral analysis using PQLX (McNamara and Buland 2004). We will show examples of seismic records during volcanic crisis and present novel results from the new seismic velocity monitoring method (Brenguier et al. 2008) using the new network. Finally, we will present some results of long-term displacement rates of the Piton de la Fournaise edifice flank using GPS data. Piton de la Fournaise volcano is a hot-spot shield volcano located on La …