Structural changes of volcanic tremor at Stromboli volcano

The occurrence of a tectonic event sufficiently close to a volcano and/or sufficiently energetic can trigger a change in its eruptive activity. Examples include Ambrym (Vanuatu), Teide (Spain), Tungurahua (Ecuador) and Villarrica (Chile). Of course the possibility that an earthquake can even trigger a new eruption has serious implications in terms of hazard. However, no serious attempt has been carried out so far to formalize the identification of these structural changes with a statistical approach. In this work a statistical approach is applied to identify structural changes in volcanic tremor recorded at Stromboli from April to July, 2006. We considered different fluctuation-type tests using the open source package strucchange written in R language [Zeileis, A., Leisch, F., Hornik, K., Kleiber, C., 2002. strucchange: an R package for testing for structural change in linear regression models. J. Stat. Softw. 7(2), 1–38]. Stromboli is a particularly interesting case study: whilst previous work [Falsaperla, S., Alparone, S., Spampinato, S., 2003. Seismic features of the June 1999 tectonic swarms in the Stromboli volcano region, Italy. J. Volcanol. Geotherm. Res., 125(1–2), 121–136] had suggested that tectonic events have no influence on volcanic activity, most recent results [Carniel, R., Tárraga, M., 2006. Can tectonic events change volcanic tremor at Stromboli? Geophys. Res. Lett., 33, L20321, doi:10.1029/2006GL027690] suggest otherwise. The aim of this work is to confirm by use of a statistical method, the presence of changes in the recorded tremor related to the occurrence of volcano-tectonic events on Stromboli, as pointed out by Carniel and Tárraga [Carniel, R., Tárraga, M., 2006. Can tectonic events change volcanic tremor at Stromboli? Geophys. Res. Lett., 33, L20321, doi:10.1029/2006GL027690]. We found that there was at least one variation in the time series associated to every earthquake, even in the cases for which previous analyses could not recognize any variation [Carniel, R., Tárraga, M., 2006. Can tectonic events change volcanic tremor at Stromboli? Geophys. Res. Lett., 33, L20321, doi:10.1029/2006GL027690].