Forecasting the evolution of the 2021 Tajogaite eruption (La Palma) from TROPOMI/PLUMETRAJ SO2 emission rates

• Mike Burton ^[1] ; Ben Esse ^[2] ; Catherine Hayer ^[1] ; Giuseppe La Spina ^[2] ; Ana Pardo Cofrades ^[1] ; María Asensio Ramos ^[4] ; José Barrancos Martínez ^[3] ; Nemesio M. Pérez ^[4]
  1. [1] University of Manchester

     University of Manchester

     Reino Unido

     
  2. [2] Istituto Nazionale di Geofisica e Vulcanologia

     Istituto Nazionale di Geofisica e Vulcanologia

     Roma Capitale, Italia

     
  3. [3] Universidad de La Laguna

     Universidad de La Laguna

     San Cristóbal de La Laguna, España

     
  4. [4] Instituto Volcanológico de Canarias (

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• Localización: Cosmológica, ISSN 2792-7423, Nº. Extra 1 (Conferencia Internacional: Erupción del Tajogaite (Los Llanos de Aridane, noviembre de 2025)), 2025, págs. 71-72
• Idioma: inglés
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• Resumen

  • Forecasting how an eruption evolves and when it will end is operationally critical yet often under quantified. We analyse the 2021 Tajogaite eruption using daily TROPOMI SO2 imagery combined with a forward trajectory implementation of PlumeTraj to reconstruct injection time-altitude, correct vertical column densities for plume height, and derive robust daily SO2 emission rates. Cumulative emissions exhibit an exponential trend after the initial fissure phase, enabling simple, testable forecasts. Total SO2 released was 1.6 ± 0.3 Mt (upper limit 1.9 Mt) (Esse et al., 2025); emissions peaked near 80 kt day-1 on 20 Sep and again at ~70 kt day-1 on 29 Sep before decaying smoothly. Fitting the cumulative series from 29 September yields a characteristic time constant τ ≈ 28 days. The eruption ceased when SO2 flux fell to ~6 % of the fitted maximum —an empirical threshold that closed the forecast loop. Fits stabilized from 20 Oct onward; using the 6 % criterion, forecast end dates were consistently within ±15 days of the true end. These results, produced and shared in near real time with the monitoring agencies, demonstrated actionable skill during the crisis...