Searching for unrest patterns at central volcanoes exploiting monitoring data from 1980 to 1999

Sara Emili¹, Manuel Verardi Nichi¹, Laura Sandri², Valerio Acocella¹

• Affiliations: ¹Department of Sciences, Roma Tre University, Roma, Italy; ²INGV Sez. Bologna, Bologna, Italy

• Presentation type: Poster

• Presentation time: Tuesday 16:30 - 18:30, Room Poster Hall

• Poster Board Number: 49

• Programme No: 6.3.8

• Theme 6 > Session 3

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Abstract

In order to forecast eruptions, it is essential to better understand unrest and determine whether this leads to eruption (eruptive unrest) or not (non-eruptive unrest). Here we contribute to this problem by studying the monitoring behaviors of central volcanoes experiencing eruptive or non-eruptive unrest. We created an original database of episodes of unrest at central volcanoes occurred between 1980 and 1999. We analysed the database in search of common and recurrent patterns among unrest types and across different volcanoes. Our analysis shows that volcanoes with mafic magma or open conduit tend to erupt more frequently. Eruptive unrest is usually characterized by volcano inflation, opening of fractures and increase in degassing, whereas deflation and stable degassing are common features for non-eruptive unrest. There is a weak relationship between the time of two subsequent eruptions and the size of the second eruption, especially for eruptions having VEI ≥4. Eruptive unrest episodes are shorter (usually lasting <2 years) than non-eruptive ones (which may last up to 5 years). The shorter duration of episodes of unrest preceding eruptions supports previous models, suggesting that magma may only be erupted for a limited period of 1-2 years before being stored in the upper crust. The similar features of unrest at calderas, derived from previous studies, suggest that pre-eruptive dynamics is independent of the presence of a central conduit.