A wide variety of volcano responses have been recorded following large earthquakes, depending on the earthquake magnitude, distance that separates the volcano from the earthquake as well as the type of on-going eruptive activity or state of equilibrium of the magmatic system. Such interactions occur at short distances by static stress diffusion [Walter and Amelung, 2006; Walter, 2007] as well as at distances of several hundred kilometers or more by dynamic stress transfer [Hill et al., 2002; Gomberg and Johnson, 2005]. They may result in the triggering of new effusive or explosive eruptions or bring changes to the dynamics of ongoing eruptions. Most commonly, increases in local tectonic or volcanic micro-seismicity have been observed following the passage of seismic waves, sometimes leading to swarms of local seismic events [Moran et al., 2004; West et al., 2005; Okubo and Wolfe, 2008] which may end in a new eruptive sequence [Cannata et al., 2010]. Several global studies found a statistically significant increase in the number of eruptions following large earthquakes [e.g., Linde and Sacks, 1998]. For volcanoes with on-going eruptive activity, large earthquakes may bring changes to the eruption dynamics leading to increases in heat flux [Harris and Ripepe, 2007; Delle Donne et al., 2010], degassing [Cigolini et al., 2007] or extrusion rate [Walter et al., 2007]. More subtle changes have also been observed such as changes in tremor activity [Moran et al., 2004; Speranza and Carniel, 2008] or increases in fumarolic emissions [Walter et al., 2007]. In many cases, however, large earthquakes occur without apparently influencing activity at nearby volcanoes, showing that interactions are not systematic and/or that insufficient data are available to understand the cause-effect relationship. Moreover, because triggering may occur with variable time delays, ranging from a few minutes to several days, weeks, months or years [Delle Donne et al., 2010; Manga and Brodsky, 2006; Marzocchi, 2002], the causal relationship is sometimes difficult to establish or is, at best, controversial.
 To understand the effects of large earthquakes on volcanoes we need to have quantitative measurements to image the full array of induced changes. While modifications in surface activity or new eruptions may be detected by visual observations, changes in the eruptive dynamics or subtle sub-surface modifications to the volcanic system, require monitoring of appropriate geophysical and geochemical parameters. The use of similar seismic signals and coda wave interferometry (CWI) technique [Poupinet et al., 1984; Snieder et al., 2002] has proved to be an efficient tool for identifying subtle sub-surface changes like increases of the propagation velocity of seismic waves preceding volcanic eruptions [Brenguier et al., 2008] or velocity decreases, near the epicenter of large earthquakes [Schaff and Beroza, 2004]. The technique relies on the comparison of similar seismic signals whose source can be natural (earthquakes) or artificial (explosions), or which may be generated by seismic noise correlation [Campillo, 2006; Shapiro and Campillo, 2004]. Changes in the medium (shallow subsurface) induce changes in the travel times of seismic waves and distortions in the waveforms which can be detected by comparing the seismic signals. The technique has previously been used to monitor temporal changes in volcanic interiors [Ratdomopurbo and Poupinet, 1995; Snieder and Hagerty, 2004; Grêt et al., 2005]. However, a major drawback in most studies is the limited, and irregular, temporal coverage of the similar signals.
 In this paper, we use highly repetitive seismic events and CWI to monitor rapid temporal changes in the structure of Yasur volcano during a period of two months including a M = 7.3 subduction earthquake which occurred 80 km from the volcano.