Rapid deployment of a seismo-acoustic experiment at Mt. Etna, Italy, following a marked increase in eruptive activity

Lead Research Organisation: University of Liverpool
Department Name: Earth, Ocean and Ecological Sciences

Abstract

The physics that define the relationships between the characteristics of seismic and acoustic signals recorded during eruptions and the rate at which gas and pyroclasts are ejected from volcanic vents remain elusive. Presently, scientists rely on data-informed models that describe relations - for example - between the magnitude of ground displacement recorded during eruptions and the height of eruption ash columns, or between the mass of material injected into the atmosphere during eruptions and the height of volcanic plumes. These relations are widely used in operational settings, for example to produce forecasts of atmospheric volcanic ash dispersal that, in turn, have implications for risk management. However, physics-based models able to confirm the validity of these empirical models are still lacking. In addition, msn of these empirical laws are based on data collected in the past with a resolution not comparable to what has become available throughout the last decade. The ongoing eruptive activity at Mt. Etna (Italy) offers a rare opportunity to collect data suitable for implementing validating new models to address this scientific gap. Eruptive activity at Etna such as that observed starting in mid-to-late February 2021, is recorded once every decade or even longer. The last comparable episode before present was in 2011. A NERC Urgency Grant is the ideal framework to seize an opportunity that is not frequently available. We propose an experiment to help addressing key scientific questions on the relations between the intensity of seismic and acoustic tremor at erupting volcanoes and the dynamics of eruption. We anticipate that future research based on the newly collected data will have impact on hazard assessment and risk mitigation at Mt. Etna, and other eruption prone areas. In order to maximize the impact of the proposed study we commit to publicly release the data collected starting from month 6 of the project.

Publications

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Minio V (2023) MISARA: Matlab Interface for Seismo-Acoustic aRray Analysis in Seismological Research Letters

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Zuccarello L (2022) Volcanic Tremor Tracks Changes in Multi-Vent Activity at Mt. Etna, Italy: Evidence From Analyses of Seismic Array Data in Geophysical Research Letters

 
Description Analyses of seismic data collected at Mt. Etna, Italy, during this grant included a period of vigorous eruptive activity at the volcano. We were able to characterize shifts in style and location of volcanic unrest across the multiple summit craters at Mt. Etna by using seismic and acousic data. We demonstrated that a migration of seismic tremor systematically anticipated the onset of the most intense phases of eruption. Our results confirmed previously proposed models of the conduit system at Mt. Etna. The results clearly demonstrated that seismic arrays can be used to identify precursory patterns leading up to eruptions, and thus, represent a powerful monitoring tool with clear potential to improve volcano early warning practices and protocols.
Exploitation Route Yes. Development of the algorithms implemented for this study for real-time use.
Sectors Energy

Environment
 
Title Dataset for: "Assessment of eruption source parameters using infrasound: a case study from the 2021 eruption of Mt. Etna, Italy" 
Description This dataset includes infrasound array waveforms recorded during eruptive activity at Mt. Etna, Italy, on June 20-21, 2021. During volcanic eruptions, the injection of volcanic ash into the atmosphere poses a well-known danger to aviation. To predict the dispersal of airborne ash and identify high-risk areas, scientists rely on observations from volcanology, as well as empirical and numerical models. These models heavily depend on what are known as eruption source parameters, which include the rate of pyroclastic material ejected from volcanic vents and the maximum altitude achieved by eruption plumes. In recent times, infrasound has gained popularity as a valuable tool for monitoring volcanoes, and researchers are continuously exploring its potential for real-time assessment of eruption source parameters. The dataset provided here was used to showcase the potential of infrasound data for near-real-time evaluation of eruption rates. Our analysis of the infrasound array data allowed us to identify coherent arrivals during the eruptive activity. By integrating these signals, we estimated the volume flow rate and flow velocity at the vent. The flow velocity values we obtained at the vent during peak paroxysmal activity were found to be between 50 and 125 meters per second, which aligned with independent estimates derived from other ground-based remote sensing data. Finally, using the flow velocities derived from infrasound we performed numerical modelling of ash plume rise to estimate the maximum height achieved by the eruption column. 
Type Of Material Database/Collection of data 
Year Produced 2023 
Provided To Others? Yes  
URL https://zenodo.org/record/8207342
 
Title Seismo-acoustic data. Mt. Etna,16 July-24 August, 2021 
Description We present a seismo-acoustic dataset recorded by a 7-element, small-aperture array, called ACPN, and an infrasound station, called CONC, deployed at Mt. Etna (Italy) during July-August, 2021. This dataset was collected during a field experiment within the framework of NERC project NE/W004771/1 and SINFONIA project, progetto Bando Ricerca Libera 2021- Delibera 214/2021-INGV. The experiment was designed to complement the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo monitoring network, and to provide unprecedented instrument coverage on the summit area of Etna. The main goal was to offer the best possible data to characterize pre- and syn-eruptive seismic tremor associated with the occurrence of surface degassing, fire fountains and atmospheric injection of volcanic ash during paroxysmal activity This data repository includes continuous raw waveforms and related metadata. The array, ACPN, was installed on Mt. Etna in proximity of the summit Bocca Nuova crater, at a distance of about 1 km from its active vents. The ACPN array consists of five broadband, and two short-period seismic sensors. ACPN was equipped with five Nanometrics Nanometrics Trillium T120 Compact seismometers (T=120s) 3 components, and two Lennartz 3D Lite-MkIII seismometers (T=1s), with flat frequency response of 0.008 - 100 Hz and 1 - 100 Hz, respectively (https://www.nanometrics.ca/products/seismometers; https://www.lennartz-electronic.de/products/seismometers/le-3dlite/). The seismic array had a maximum aperture of 200 m, and both the location and geometry were chosen considering three main criteria: i) site accessibility and safety of personnel; ii) minimising differences in elevation between sensors within each array; iii) optimizing the detection and discrimination of activity from all summit craters. The infrasonic station CONC was located at an elevation of about 1800 m a.s.l., at a distance of about 5000 m from the craters. The CONC station was equipped with IST-2018 broadband microphones, frequency response between 60 mHz and 40 Hz, developed by The ISTerre, Université Savoie Mont Blanc, France (Grangeon and Lesage, 2019). Data were sampled at 100 Hz using DIGOS DATACUBE3 digital data recorders (https://digos.eu/CUBE/DATA-CUBE-Datasheet-2017-02.pdf). DATACUBE recorders have an effective resolution of 22.4 bit (at 100 Hz), and a GPS timing accuracy of 1 µs. The equipment was made available within the framework of an established collaboration between the Instituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, University of Liverpool (UK)) and the Dublin Institute for Advanced Studies (Ireland). 
Type Of Material Database/Collection of data 
Year Produced 2022 
Provided To Others? Yes  
URL https://zenodo.org/record/6627580