Gas hazard: an often neglected natural risk in volcanic areas

Abstract

Volcanic areas release huge amounts of gases, which apart from having important influences on the global climate could have strong impact on human health. Gases have both acute and chronic effects. Carbon Dioxide and Sulphur gases are the main gases responsible for acute mortality due to their asphyxiating and/or toxic properties. On the contrary Mercury and Radon have important chronic effects respectively for its toxicity and radioactivity.The problem has long been neglected until the "Lake Nyos" catastrophe in 1986, in which about 1700 people were killed by a volcanic CO 2 emission, attracted the worldwide attention of the mass media.In this paper we present some studies on gas hazards in three different volcanic systems chosen for their different activity status: Mt. Etna (Italy), characterised by frequent activity with a mean CO 2 emission of about 450 kg s -1 ; Pantelleria island (Italy) at present in quiescent status and a CO 2 emission of about 12 kg s -1 ; and Sousaki (Greece) a recent (Quaternary) but now extinct volcano with a CO 2 emission of about 0.6 kg s -1 . In all three systems the main problems arise from CO 2 emissions while secondary problems are due to SO 2 and Hg (Etna), H 2 S (Sousaki) and Rn (Pantelleria).

Geothermal point sources identified in a fumarolic ice cave on Erebus volcano, Antarctica using fiber optic distributed temperature sensing

“…A pressure drop causes a temperature increase throughout the cave, and a pressure increase is associated with temperature drop. These findings lend support to the concept of diffuse degassing in response to barometric pumping and suggest that meteorological observation and prediction could be used to prevent injuries and fatalities such as those that occurred on Etna in 1993 [D'Alessandro, 2006] and Mammoth Mountain in 2006 [Rogie et al, 2001].…”

“…Erebus is thus an excellent laboratory for the study of diffuse flank degassing. A better understanding of the dynamics at work in the Erebus FIC can improve management and mitigation at the many volcanic areas around the world where flank degassing is a poorly understood hazard [D'Alessandro, 2006]. As structures where warm, vapor-rich gas is channeled through a frozen barrier into a dry, low-pressure (about 600 hPa) environment well below freezing, the FIC systems may share dynamics with the "misty ice caverns" [Spencer, 2009] theorized to exist beneath geysers observed emitting H 2 O and salts near the south pole of Saturn's moon Enceladus [Matson et al, 2007].…”

Numerical modelling of the volcanic plume dispersion from the hydrothermal system of La Soufrière de Guadeloupe

“…breathing difficulties; Beauchamp et al 1984;Baxter et al 1990;WHO 2000;Guidotti 2010] and fatalities [Williams-Jones and Rymer 2015]. Moreover, persistent volatile degassing, known as passive degassing, can be as harmful as sporadic effusive/explosive eruptions [D'Alessandro 2006;Oppenheimer et al 2011;Fischer and Chiodini 2015], especially for long-term (years to decades) degassing. Indeed, long-term exposure to plumes generated by passive degassing and/or fumarolic emissions has a general impact on vegetation, especially crops [Baxter et al 1982;Tortini et al 2017], and on human health, even at very low concentration < 1 ppm) [ATSDR 1999;CalOEHHA 2000;U.S.…”

An analysis of volcanic SO2 and ash emissions from Copahue volcano

“…Sulfur gases are one of the most abundant species in volcanic eruptions. The relative abundance of sulfur depends on the thermodynamic characteristics of the volcanic system (pressure, temperature, and oxygen fugacity) (Alessandro, 2006). Species abundance depends on the balance between a hydrous fluid (exsolved gas) at the top and a silicate melt in the magma chamber below (Symonds et al, 1994).…”

“…Sulfur dioxide is a colorless gas with a characteristic odor that can be perceived at different concentration levels, generally from 0.3 to 1.4 ppm, depending on individual sensitivity. It is easily detectable at 3.0 ppm (Alessandro, 2006), and its toxic level for continuous exposure is 10.0-15.0 ppm (IVHHN, 2020). The atmospheric half-life of sulfur dioxide is 6-24 h; consequently, only about 5% of the gas emitted is found in the lower atmosphere after 1-4 days (Finlayson-Pitts and Pitts, 1986).…”