Imaging preeruptive and coeruptive structural and mechanical changes of a volcano with ambient seismic noise

Abstract

[1] Forecasting the location of an eruption is of primary importance for risk management in volcanic regions. Locating the underground structural changes associated with a potential eruption is also a key issue to better understand the dynamics at work in a volcano. Using recent results in wave physics, we develop an imaging procedure that is based on the sensitivity of multiply scattered waves to weak changes in heterogeneous media. This procedure allows to locate changes in both mechanical and scattering properties of the studied medium. We study ambient seismic noise from 19 broadband stations at the active volcano Piton de la Fournaise on Reunion Island, recorded from June to December 2010. During this period, two volcanic eruptions occurred at two different locations. We calculate the noise cross correlations and study two types of changes in the coda: apparent velocity variations related to changes in the elastic properties of the medium; and, waveform decoherence associated with variations in the scattering, and thus the geological structures. We observe that the temporal variations of both of these parameters provide potential precursors of volcanic eruptions at Piton de la Fournaise. The locations determined from the preeruptive and coeruptive changes in both parameters are in good agreement with the actual eruptive activities. These data demonstrate that the coda of ambient noise correlations contains deterministic information on the locations of the eruptive processes in an active volcano. Our analysis offers an original and significant constraint for the localization of forthcoming volcanic eruptions.Citation: Obermann, A., T. Planès, E. Larose, and M. Campillo (2013), Imaging preeruptive and coeruptive structural and mechanical changes of a volcano with ambient seismic noise,

Response of hydrothermal system to stress transients at Lassen Volcanic Center, California, inferred from seismic interferometry with ambient noise

“…As mentioned in Obermann et al (2013a), the estimation of the transport mean free path is often difficult. However, if we use l = 50 km that was used in Obermann et al (2013b) for Piton de la Fournaise volcano together with c = 2.0-3.0 kms…”

A comparison of methods to estimate seismic phase delays: numerical examples for coda wave interferometry

“…(1). Many authors continue to work on analytical and numerical methods to approximate and compute these sensitivity kernels (Pacheco & Snieder 2005, 2006Obermann et al 2013;Mayor et al 2014;Planès et al 2014Planès et al , 2015Richter et al 2014), but any further treatment of this part of the problem is beyond the scope of this paper. The remainder of this paper focuses on our ability measure τ .…”

Local time in diffusive media and applications to imaging

“…Defects appearing in a concrete structure have been located correctly by an error minimization inversion [8]. Local time has been used as a kernel in seismology to observe the depth sensitivity of the seismic coda to velocity perturbations [9]. In a volcano, precursor structural changes to an eruption have been observed using LOCADIFF [9].…”

“…Local time has been used as a kernel in seismology to observe the depth sensitivity of the seismic coda to velocity perturbations [9]. In a volcano, precursor structural changes to an eruption have been observed using LOCADIFF [9]. of the diffuse waves to a change in the medium is proportionnal to the time spent at the position where the change has occured.…”