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Cities on Volcanoes 5, Shimabara, Japan, November 2007

Submitted by Claire on Mon, 08/11/2008 - 09:14

4th IVHHN Workshop Summary

The IVHHN workshop opened with an update of recent activities including the production of pamphlets on volcanic ashfall hazards, which are available in a variety of languages. The first focus session explored volcanic soil gases and gassing accidents. This was illustrated with examples from Italy and Japan, notably Miyakejima where islanders were evacuated for over four years due to the levels of volcanic emissions (Baxter).

The second section looked at the rapid grain size analysis of ash for health hazard assessment. This involves sieving the ash and using an equation to determine the percentage of ash fine enough to enter the lungs. This is a quick way for hazard managers to decide whether to distribute dust masks or even evacuate a population and is particularly useful in countries where state of the art techniques are unavailable (Horwell).

The final section explored the psychological issues of evacuation; the local example of Mt Unzen was used, where 7,000 people were evacuated – a proportion of which suffered from post-traumatic stress disorder (Baxter). A second case study centred on the 2005 Surtseyan eruption on Ambae Island, Vanuatu. This evacuation was co-ordinated by the villagers themselves, following their own interpretation of the threat and highlighted how well people can organise themselves when they take responsibility for their own safety (Cronin). The final case study was Hawaii and underlined the main concerns of evacuated people, including the quality of their shelters, their ability to continue work and the problems of resettlement and land-titles. The workshop finished with a discussion of the issues raised; inter alia the potentially high levels of volcanic gas present at Japanese hot spring health-spas and their lack of monitoring.  

Health Hazards Session Summary

The Health hazards of co-existing with active volcanoes conference session covered a variety of topics, including: affected populations and response workers, soil gases and river waters, and mineralogical methods.

Safety measures taken by civil defence authorities need to adapt to changing stages of volcanic gas emission as appropriate; such as the four stages of preventative measures taken at Mijakejima. Special provisions need to be made for those working as part of the emergency response team to protect their health and safety (Ishihara). In areas of persistent degassing a multi-causality approach of host-agent-environment should be employed to prevent accidents. Greater warning is needed in areas of potential threat (Yano). Soil gases in volcanic areas, especially CO2, radon and H2S need to be more widely understood in terms of potential health hazards posed; H2S is considered most important for investigation. Early warning systems and hazard maps are particularly useful for preventing accidents. (Nogami et al).

Studies have been undertaken into the relationship between radon concentration and volcanic activity; levels of lung cancer were also examined in Tarumizu city near Sakurajima (Kobayashi et al). Volcanic gases in water can also cause problems; Kusatsu is a useful model of the neutralisation of volcanic river water, in this instance it has been contaminated by arsenic from acidic hot springs and is neutralised with lime water. (Kikawada et al).

Studies of cristobalite formation in the Montserrat dome are leading to the development of new mineralogical analytical methods which will enhance toxicological understanding (Horwell et al). Multidisciplinary studies between volcanic modellers and mineralogists working on ash fall modelling from Mount Etna provide novel approaches for risk assessment for this particular hazard (Neri et al.)

The conference provided a unique opportunity to learn more about different disciplines in volcanology and in particular gave us a greater understanding of the field of volcanic health hazards. An invaluable aspect of the conference was the opportunity of seeing posters from the local Shimabara medical community which detailed the variety of issues they experienced following the eruption of Mt Unzen.

Summary by Sabina Michnowicz, PhD student, Durham University, UK