Probabilistic modeling of future volcanic eruptions at Mount Etna

Abstract

[1] The statistical analysis of volcanic activity at Mt Etna was conducted with the twofold aim of (1) constructing a probability map for vent opening of future flank eruptions and (2) forecasting the expected number of eruptive events at the summit craters. The spatiotemporal map of new vent opening at Etna volcano is based on the analysis of spatial locations and frequency of flank eruptions starting from 1610. Thanks to the completeness and accuracy of historical data over the last four centuries, we examined in detail the spatial and temporal distribution of flank eruptions showing that effusive events follow a nonhomogenous Poisson process with space-time varying intensities. After demonstrating the spatial nonhomogeneity and the temporal nonstationarity of flank eruptions at Etna, we calculated the recurrence rates (events expected per unit area per unit time) and produced different spatiotemporal probability maps of new vent opening in the next 1, 10 and 50 years. These probabilistic maps have an immediate use in evaluating the future timing and areas of Etna prone to volcanic hazards. Finally, the results of the analysis of the persistent summit activity during the last 110 years indicate that the hazard rate for eruptive events is not constant with time, differs for each summit crater of Mt Etna, highlighting a general increase in the eruptive frequency starting from the middle of last century and particularly from 1971, when the SE crater was formed.

Forecasting the duration of volcanic eruptions: an empirical probabilistic model

“…Etna began in the late 1970s and early 1980s focussing on patterns in historic eruptions and predicting the location of future activity (Frazzetta and Romano 1978;Guest and Murray 1979;Duncan et al 1981). Since then, numerous studies have built on this work by analysing catalogues of historic eruptions (Mulargia et al 1985;Behncke and Neri 2003;Branca and Del Carlo 2004;Salvi et al 2006;Neri et al 2011;Smethurst et al 2009;Passarelli et al 2010;Proietti et al 2011) and producing susceptibility and probabilistic hazard maps of surrounding areas Bisson et al 2009;Behncke et al 2005;Crisci et al 2010;Harris et al 2011;Cappello et al 2012Cappello et al , 2013.…”

“…Etna: persistent activity from summit vents and periodic activity from eruptive fissures on the volcano's flanks (Guest and Murray 1979;Duncan et al 1981;Acocella and Neri 2003;Behncke and Neri 2003;Branca and Del Carlo 2005;Crisci et al 2010). Despite the typically explosive nature of summit activity, its effects are often localised to within a few hundred/thousand metres of the eruption site and therefore its threat to property and surrounding populations is confined above 1600-1800 m above sea level; consequently, only the tourist facilities are potentially exposed to the risk of lava invasion (Duncan et al 1981;Proietti et al 2011;Cappello et al 2013). However, flank eruptions tend to produce lava flows that can extend for far greater distances and to lower elevations making them the greatest hazard on Mt.…”

“…Etna's eruptive activity dates back to Greek and Roman epochs (Branca and Del Carlo 2004;Tanguy et al 2007). However, the records are often only considered to be complete after 1600 AD (Mulargia et al 1985;Behncke and Neri 2003;Del Carlo 2004, 2005;Behncke et al 2005;Tanguy et al 2007;Cappello et al 2013). Figure 2a shows an apparent increase in eruption frequency since 1300 AD which is most probably an artefact of reporting.…”

“…A fundamental assumption of any investigation using historical eruption data as an insight into future activity is that the character of past eruptions is a good indicator of the volcano's future activity (Chester et al 1985;Behncke and Neri 2003;Behncke et al 2005;Cappello et al 2013). …”

“…After 1669 eruption durations range from 0.5 to 473 days and there has been a general increase in eruption frequency with time that is not an artefact of reporting (Behncke and Neri 2003;Behncke et al 2005;Branca and Del Carlo 2005;Cappello et al 2013). In particular, dramatic increases in eruption frequency and output rate have been recognised following 1971 Behncke et al 2005;Branca and Del Carlo 2005;Smethurst et al 2009;Cappello et al 2013).…”