Eruptive Styles Recognition Using High Temporal Resolution Geostationary Infrared Satellite Data

Abstract

The high temporal resolution of the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument aboard Meteosat Second Generation (MSG) provides the opportunity to investigate eruptive processes and discriminate different styles of volcanic activity. To this goal, a new detection method based on the wavelet transform of SEVIRI infrared data is proposed. A statistical analysis is performed on wavelet smoothed data derived from SEVIRI Mid-Infrared( MIR) radiances collected from 2011 to 2017 on Mt Etna (Italy) volcano. Time-series analysis of the kurtosis of the radiance distribution allows for reliable hot-spot detection and precise timing of the start and end of eruptive events. Combined kurtosis and gradient trends allow for discrimination of the different activity styles of the volcano, from effusive lava flow, through Strombolian explosions, to paroxysmal fountaining. The same data also allow for the prediction, at the onset of an eruption, of what will be its dominant eruptive style at later stages. The results obtained have been validated against ground-based and literature data. Keywords: volcanic eruption interpretation; eruption forecasting; MSG SEVIRI; wavelet; remote sensing; thermal measurements; lava fountain; lava flow; Mt.Etna; eruptive style 1. Introduction Determining the beginning and end of an eruption, and forecasting what will be the dominant eruption style, are equally important objectives, crucial for hazard assessment. Satellite sensors have been increasingly employed for operational monitoring of volcanic thermal features as for example the geostationary Spinning Enhanced Visible and InfraRed Imager (SEVIRI) instrument on board the geostationary Meteosat Second Generation (MSG) satellite [1–4] and the Geostationary Operational Environmental Satellites (GOES) [5], or the polar Moderate Resolution Imaging Spectroradiometer (MODIS) [6], the Along Track Scanning Radiometer (ATSR) [7] and the advanced very-high-resolution radiometer (AVHRR) [3,8–12], on board respectively of the NASA Terra/Aqua, the ESA-ENVISAT, and the NOAA satellites. In spite of its coarse spatial resolution, the high temporal rate of the geostationary systems represents an important tool for volcano monitoring (e.g., [13–15]). In particular, SEVIRI has 12 spectral channels from visible to thermal infrared, a spatial resolution of 3 km at nadir and a high temporal resolution that ranges from 15 min (earth full disk (EFD)) to 5 min (rapid scan mode (RSM) over Europe and Northern Africa). Exploiting these characteristics, SEVIRI allows a precise timing of the early phase of an eruption and almost a continuous monitoring of volcanic activity from the source to the atmosphere [4,16]. The SEVIRI data are collected in real time from a Meteosat-8 ground station antenna operating from 2010 at Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Rome (Italy)