%0 Journal Article
%T Ionospheric Disturbances Recorded by DEMETER Satellite over Active Volcanoes: From August 2004 to December 2010
%A Jacques Zlotnicki
%A Feng Li
%A Michel Parrot
%J International Journal of Geophysics
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/530865
%X The study analyzes electromagnetic data and plasma characteristics in the ionosphere recorded by DEMETER microsatellite over erupting volcanoes during the life of the mission: from August 2004 to December 2010. The time window in which anomalous changes are searched brackets the onset of the eruptive activity from 60 days before to 15 days after the period during which most pre- and posteruptive phenomena are amplified. 73 volcanoes have entered into eruption. For 58 of them, 269 anomalies were found in relation to 89 eruptions. They are distributed in 5 types, similarly to the ones observed above impeding earthquakes. The two main types are electrostatic turbulence (type 1, 23.4%) and electromagnetic emissions (type 2, 69.5%). The maximum number of types 1 and 2 anomalies is recorded between 30 and 15 days before the surface activity, corresponding to the period of accelerating phenomena. The amount of anomalies seems related to the powerfulness of the eruptions. The appearance seems dependant on the likelihood to release bursts of gases during the preparatory eruptive phase. For the huge centenary October 26, 2010, Merapi (Indonesia) eruption, 9 ionospheric type 2 anomalies appeared before the eruption. They mainly emerge during the mechanical fatigue stage during which microfracturing occurs. 1. Introduction The identification of electric and magnetic signals related to earthquakes and volcanic activity has always been a challenge for Science. The long term objectives are (i) to identify consistent and cross-correlated signals related to natural disasters and (ii) to resolve the characteristics of the impending earthquakes (magnitude, location, and occurrence time) and the features of forthcoming volcanic eruptions (type of activity, powerfulness, occurrence time of the burst, and the vanishing surface activity) with a high degree of reliability for mitigating human fatalities and economical disorganization. These targets will contribute to mitigate human fatalities and economical disorganization. During almost two centuries, only land observations were feasible and a part of them has shown that electric and/or magnetic signals (called hereafter electromagnetic (EM) signals) may occur before earthquakes and volcanic eruptions. But till now, the recognition well in advance of the characteristics of a future disaster with a large degree of confidence is not yet achieved. However, results obtained on active faults and active volcanoes have reached different levels of achievements. Along with active faults, a number of observations of preseismic
%U http://www.hindawi.com/journals/ijge/2013/530865/