MODIS thermal anomalies during strombolian activity at Stromboli

We investigated the spectral radiance of Stromboli volcano through a time-series of more than 1200 nighttimes and daytimes MODIS granules. MODIS images allowed us to analyse the infrared radiation of Stromboli volcano during the period spanning between 1 January 2008 and 4 September 2008. MODIS data has been resampled within a spatial mask (15 km X 15 km) including the volcano. Then we applied a cloud mask algorithm and the NTI to the all pixels in order to detect the pixel containing the thermal anomalies. According to this principle, the MODVOLC algorithm detects an alert whenever a pixel has an NTI higher than a fixed threshold (-0.8); such thresholds were settled in order to avoid false alarms on a global scale. At Stromboli volcano a clear seasonal pattern is evident for the measured specific NTI trend and many thermal anomalies may be detected when this parameter is lower than -0.8, as well. Therefore we processed all data by means of an automatic routine without setting any fixed threshold. Since during typical strombolian activity, thermal anomalies are located within the crater area, we monitored the pixel with highest NTI within the spatial mask. We suggest that the thermal energy measured for these peaks can be better related to the amount of lava erupted, thus providing a tools to refine the estimate of the effusion rates during the typical strombolian activity.