EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Variations of Stromboli activity related to the 2019 paroxysmal phase revealed by SOM clustering of seismo-acoustic data and its comparison with video recordings and GBInSAR measurements 

Flora Giudicepietro1, Sonia Calvari2, Luca D'Auria3, Federico Di Traglia4, Lukas Layer5,6, Giovanni Macedonio1, Teresa Caputo1, Walter De Cesare1, Gaetana Ganci2, Marcello Martini1, Massimo Orazi1, Rosario Peluso1, Giovanni Scarpato1, Laura Spina7, Teresa Nolesini8, Nicola Casagli4,9, Anna Tramelli1, and Antonietta M. Esposito1
Flora Giudicepietro et al.
  • 1Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Vesuviano, Napoli, Italy (,,,,,,
  • 2Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Catania, Italy (,
  • 3Instituto Volcanológico de Canarias (INVOLCAN), San Cristobal de La Laguna, Spain (
  • 4Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Trieste, Italy (,
  • 5Università degli Studi di Napoli “Federico II”, Napoli, Italy (
  • 6Istituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova, Italy (
  • 7Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma 1, Roma, Italy (
  • 8Centro per la Protezione Civile, Università degli Studi di Firenze, Firenze, Italy (
  • 9Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Firenze, Italy (

Two paroxysmal explosions occurred on Stromboli in the summer of 2019 (July 3 and August 28). The first of these explosions resulted in the death of one person. Furthermore, an effusive phase began on July 3 and lasted until August 30, 2019. This dangerous eruptive phase of Stromboli was not preceded by evident variations in the geophysical parameters routinely monitored, therefore the volcano was considered to be in a state of normal activity.

To investigate the precursors of the 2019 eruptive crisis and explain the absence of variations in the parameters routinely monitored, we analyzed the seismo-acoustic signals with an unsupervised neural network capable of discovering hidden structures of the data. We clustered about 14,200 seismo-acoustic events recorded in 10 months (November 15, 2018 - September 15, 2019) using a Self-Organizing Map (SOM). Then we compared the clustering result with the images of visible and thermal monitoring cameras, that were installed and managed by the Istituto Nazionale di Geofisica e Vulcanologia, Italy, and with the Ground-Based Interferometric Synthetic Aperture Radar displacement measurements of the summit area of the volcano recorded by BGInSAR devices, which were installed and managed by Università Degli Studi di Firenze, Italy.

The SOM analysis of the seismo-acoustic features associated with the selected dataset of explosions allowed us to recognize three main clusters in the period November 15, 2018 - September 15, 2019. We named these three clusters Red, Blue, and Green. The analysis of a subset of the selected explosions (approximately 180 events) through the videos of the visible and thermal monitoring cameras allowed us to associate distinct explosive types to the three main seismo-acoustic clusters. In particular, the cluster Red was associated with explosions characterized by well collimated oriented jets of ~ 200 m height, which eject incandescent ballistics and produce a significant infrasonic transient. The cluster Blue was associated with gas explosions with a height of 10 - 20 m and with little or no ash and pyroclastic fragment ejection. These types of explosions may not be detected by the camera recordings and infrasonic sensors. On the contrary, they are well recorded in the VLP seismic signals (filtered in the 0.05 - 0.5 Hz frequency band). The cluster Green includes explosions characterized by the emission of incandescent spatter-like fragments, with a wide range of ejection angles and hemispherical shape. The explosions of the cluster Red are mainly generated in the NE vent region, whereas the explosions of clusters Blue and Green are generally located in the central and SW vent regions.

Comparing these results with the temporal evolution of the displacement of the summit area measured by the GBInSAR device, we discovered that the variations of the eruptive style that were highlighted by the SOM clustering of the seismic-acoustic features are recognizable in the ground deformation temporal pattern. Our findings are relevant for the improvement of monitoring of volcanoes with persistent activity and volcano early warning.

How to cite: Giudicepietro, F., Calvari, S., D'Auria, L., Di Traglia, F., Layer, L., Macedonio, G., Caputo, T., De Cesare, W., Ganci, G., Martini, M., Orazi, M., Peluso, R., Scarpato, G., Spina, L., Nolesini, T., Casagli, N., Tramelli, A., and Esposito, A. M.: Variations of Stromboli activity related to the 2019 paroxysmal phase revealed by SOM clustering of seismo-acoustic data and its comparison with video recordings and GBInSAR measurements , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10482,, 2022.