A search for the volcanomagnetic signal at Deception volcano

(South Shetland I., Antarctica)
Alicia Garc¡a (¹), Isabel Blanco (¹), J. Miquel Torta (¹), M. Mar Astiz (²),
Jesús M. Ibáñez (³) and Ramón Ortiz (¹)
(1) Departamento de Volcanología, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain
(2) E.T.S. Arquitectura, Universidad Politécnica de Madrid, Spain
(3) Instituto Andaluz de Geofísica, Granada, Spain

Abstract

After the increase in seismic activity detected during the 1991-1992 summer survey at Deception Island, the continuous measurement of total magnetic intensity was included among the different techniques used to monitor this active volcano. The Polish geomagnetic observatory Arctowski, located on King George Island, served as a reference station, and changes in the differences between the daily mean values at both stations were interpreted as indicators of volcanomagnetic effects at Deception. A magnetic station in continuous recording mode was also installed during the 1993-1994 and 1994-1995 surveys. During the latter, a second magnetometer was deployed on Deception Island, and a third one in the vicinity of the Spanish Antarctic Station on Livingston Island (at a distance of 35 km) and was used as a reference station. The results from the first survey suggest that a small magma injection, responsible for the seismic re-activation, could produce a volcanomagnetic effect, detected as a slight change in the difference between Deception and Arctowski. On the other hand, a long term variation starting at that moment seems to indicate a thermomagnetic effect. However the short register period of only two stations do not allow the sources to be modelled. The future deployment of a magnetic array during the austral summer surveys, throughout the volcano, and of a permanent geomagnetic observatory at Livingston I. is aimed at further observations of magnetic transients of volcanic origin at Deception Island.