We present a new method that uses cooling curves, apparent in high temporal resolution thermal data acquired by geostationary sensors, to estimate erupted volumes and mean output rates during short lava fountaining events. The 15 minute temporal resolution of the data allows phases of waxing and peak activity to be identified during short (150‐to‐810 minute‐long) events. Cooling curves, which decay over 8‐to‐21 hour‐periods following the fountaining event, can also be identified. Application to 19 fountaining events recorded at Etna by MSG's SEVIRI sensor between 10 January 2011 and 9 January 2012, yields a total erupted dense rock lava volume of ∼28 × 106 m3, with a maximum intensity of 227 m3 s−1being obtained for the 12 August 2011 event. The time‐averaged output over the year was 0.9 m3 s−1, this being the same as the rate that has characterized Etna's effusive activity for the last 40 years.