Measuring the height of the eruptive column during the 2021 eruption of Cumbre Vieja (La Palma Island, Canary Islands)

Last year's almost 3-month eruption on the island of La Palma was a Strombolian eruption. The explosive behaviour has been very variable and significant throughout the eruption.  The IGN (Instituto Geográfico Nacional) measured the height of the eruptive column from the first days of the eruption using visual cameras. The main camera used was one from the IAC (Instituto Astrofísico de Canarias), located at 2365 masl altitude and 16.5 km north of the main vent.  The cameras were calibrated with geodetic techniques to check the accuracy of the measurements and avoid errors due to small displacements or rotation of the cameras. The effect of wind at different heights was also taken into account in the assessment of the plume height. The maximum value of the column height measured was 8500 masl, which occurred hours before the end of the eruption, while the characteristic value was about 3500 masl. This work shows the evolution of the column height throughout the eruptive period and its correlation with different volcano monitoring techniques. The measurement of the eruptive column height is of great relevance in reducing the potential impact of volcanic ash on civil aviation, as significant changes in the height of the eruptive plume are communicated to the VAAC (Volcanic Ash Advisory Centre) in Toulouse to be taken into account in volcanic ash cloud forecasts.