Inverting the source mechanism of Strombolian explosions at Mt. Yasur, Vanuatu, using a multi-parameter dataset

Abstract The source mechanism of Strombolian explosions at Mt. Yasur, Vanuatu, is analyzed using a unique data set which enables us to combine different methodologies. The novelty of the approach presented here lies in the combination of seismic, acoustic and Doppler-radar data. Thus, using infrasound and Doppler radar observations we are able to provide independent estimates of the volume of the eruptive source. In the following, we show that a correlation exists between source volume and the maximum particle velocity of the expelled volcanic products. In order to determine the source location and the associated mechanism and to compare those two methods, we use time reversal imaging and moment tensor inversion. While the first method also applies to extended sources, the latter might be biased by its intrinsic point source approximation. We show that time reversal imaging can deliver an estimate of the source depth without any a priori assumptions even in an unfavorable scenario in terms of topography and receiver setup. The inverted source mechanism retrieved from moment tensor inversion is found to be largely isotropic, with minor deviatoric components. The inverted source location points towards an area to the north-west of the active craters, indicative of a common feeder system of the activity at Mt. Yasur. However, it is also evident, that to fully locate the source of Strombolian activity at Yasur location precision must be enhanced.

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