Increased activity on Ebeko Volcano, Paramushir I., North Kurils in 2005–2006

Abstract

In recent years the gas hydrothermal activity of Ebeko Volcano has been characterized by a constant heat flow and a constant chemical composition of water and fumarole gases. The volcano’s activity suddenly increased on January 27, 2005. Two high-output steam-gas jets 5 m across formed in the Active Funnel of the North Crater. A new high-output, high-temperature, fumarole field originated in the funnel in July 2005. Changes have been recorded in the chemical composition of fumarole gases. Ratios between individual components of the gas were calculated, with the ratios being geochemical precursors of eruptions for the volcano under study. Based on these results and on the very fact of increased fumarole activity on Ebeko, an intermediate-term forecast of explosive eruptions has been developed. Atmospheric contamination by a toxic gas (hydrogen sulfide) is described. It was previously thought that toxic gases pose a short-lived threat only to the population of the town of Severo-Kuril’sk because of frequent strong winds prevailing there. It is shown that the presence of a snow cover during increased activity on Ebeko sharply enhances the hazard of contamination by toxic gases, the hazard being constant both on the volcano itself and in the Severo-Kuril’sk area.