Thermal imaging of Nisyros volcano (Aegean Sea) using ASTER data: estimation of radiative heat flux

Abstract

A time series of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images (AST08) have been processed to allow radiative heat flux estimations of the Nisyros volcano. ASTER night-time images were acquired on four different dates: 7 April 2001, 13 June 2002, 26 October 2002 and 23 July 2005. The results show a steady state energy release with heat fluxes ranging from 15 to 30 W m⁻² over the craters of Kaminakia, Polyvotis and Stefanos, respectively. It is suggested that this range of values indicates a background heat flux of this volcano following the unrest of 1995–1997, and that the volcano has entered again into the quiet phase. Also, on the basis of the average spatial extent of the thermal anomaly a total radiative heat flux of 36 MW was estimated at the moment of ASTER overpass. Heat flux values for Nisyros are in good agreement with other published estimates derived from low-temperature fumarolic volcanoes (Stromboli and Vulcano, Italy) using Landsat TM data. It is also evidenced that the ASTER radiometer can be used as an important imaging tool for the monitoring of geophysical properties associated to volcanic activity, as is the volcanic heat flux.

Acknowledgements

This research was funded by the GEOWARN project (IST-1999-12310), The National Observatory of Athens and the General Secretariat for Research and Technology of Greece. GP was funded by the State Scholarships Foundation of Greece (IKY). We thank our colleagues V. Dietrich, S. Vassilopoulou, V. Sakkas, G. Vougioukalakis, G. Chiodini, K. Haritos and G. Stavrakakis for their comments and field assistance. We also thank two anonymous reviewers and the journal editor for comments and suggestions. We are indebted to the people of the Nisyros Municipality for their help. The meteorological data were retrieved from http://weather.uwyo.edu/upperair/sounding.html