Analysis of volcanic threat from Nisyros Island, Greece, with implications for aviation and population exposure

Abstract

Abstract. Nisyros island in the South Aegean volcanic arc, Greece, is a Quaternary composite volcano with a 3.8 km wide caldera that in 1996 entered a volcano-seismic crisis, which heralded the islands' return to a state of unrest. The caldera has been the locus of at least thirteen phreatic eruptions in historical times, the most recent in 1888, and the system is still presently affected by considerable hydrothermal activity. Although the recent unrest waned off without eruption, there are still open questions relating to the current threat of volcanic activity from the island. Here, we perform a detailed and systematic assessment of the volcanic threat of Nisyros using a threat analysis protocol established as part of the USGS National Volcano Early Warning System (NVEWS). The evaluation involves a methodical assessment of fifteen hazard and exposure factors, and is based on a score system, whereby the higher the score, the higher the threat is. Uncertainty in assessment criteria are expressed by allowing for a conservative and an extreme score for each factor. We draw our analysis from published data as well as from results of our research on Nisyros over the past years. Our analysis yields a conservative threat score of 163 and an extreme score of 262. The most adverse exposure factors include significant scores relating to aviation and population exposure to volcanic hazards from Nisyros. When looked at in comparison to US volcanoes both scores place Nisyros in the "Very High Threat (VHT)" category, grouping it with volcanoes such as Redoubt, Mount Ranier and Crater Lake. We identify a short-fall in recommended surveillance efforts for VHT volcanoes given existing monitoring capabilities on the island. We discuss potential pitfalls of applying the NVEWS scheme to Nisyros and suggest potential adaptaCorrespondence to: J. Gottsmann (j.gottsmann@bristol.ac.uk) tion of analysis scheme to match industrial and societal conditions in Europe. At the same time, our findings indicate that that volcanic threat posed by Nisyros volcano may currently be underestimated.

Eruptive scenarios of phonolitic volcanism at Teide–Pico Viejo volcanic complex (Tenerife, Canary Islands)

“…Other authors have applied NVEWS analysis to other volcanoes, such as Kinvig et al (2010), who recently applied this analysis to Nysiros volcano (Greece). In this paper, we applied the NVEWS scheme in order to quantify the threat posed by TPV and to facilitate the comparison with other volcanoes.…”

Late Holocene terrestrial tephra record at western Anatolia, Turkey: Possible evidence of an explosive eruption outside Santorini in the eastern Mediterranean

“…The most recent phreatic eruption took place in 1867 A.D. and currently it forms a high threat for inhabitants (Zouzias and Seymour, 2007;Kinvig et al, 2010). Next to Nisyros, the island of Yali is formed by the youngest deposits of the Kos-Nisyros volcanic complex.…”

The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model

“…Understanding the dynamics of the degassing close to the surface at Nisyros is of relevance, as the volcano is currently ranked in the "Very High Threat" class (Kinvig et al, 2010), considering the vulnerability of the population (∼ 1000) and seasonal tourists (∼ 60 000). The Stefanos crater was chosen for our study because of a recent increase in fumarole activity and outflow of melted sulfur and hot mud (Papadopoulos et al, 1998;Chiodini et al, 2002;Sachpazi et al, 2002;Vougioukalakis and Fytikas, 2005;Lagios et al, 2007), as well as its strong thermal signature in comparison to other phreatic craters (Lagios et al, 2007;Ganas et al, 2010).…”