Multi-Sensor Analysis of a Weak and Long-Lasting Volcanic Plume Emission

Simona Scollo,Dario Stelitano,Antonella Boselli,Michele Prestifilippo,Luca Merucci,Stefano Corradini,Alessia Sannino,Ricardo Zanmar Sanchez,Giuseppe Leto,Lorenzo Guerrieri

doi:10.3390/rs12233866

Abstract

Volcanic emissions are a well-known hazard that can have serious impacts on local populations and aviation operations. Whereas several remote sensing observations detect high-intensity explosive eruptions, few studies focus on low intensity and long-lasting volcanic emissions. In this work, we have managed to fully characterize those events by analyzing the volcanic plume produced on the last day of the 2018 Christmas eruption at Mt. Etna, in Italy. We combined data from a visible calibrated camera, a multi-wavelength elastic/Raman Lidar system, from SEVIRI (EUMETSAT-MSG) and MODIS (NASA-Terra/Aqua) satellites and, for the first time, data from an automatic sun-photometer of the aerosol robotic network (AERONET). Results show that the volcanic plume height, ranging between 4.5 and 6 km at the source, decreased by about 0.5 km after 25 km. Moreover, the volcanic plume was detectable by the satellites up to a distance of about 400 km and contained very fine particles with a mean effective radius of about 7 µm. In some time intervals, volcanic ash mass concentration values were around the aviation safety thresholds of 2 × 10−3 g m−3. Of note, Lidar observations show two main stratifications of about 0.25 km, which were not observed at the volcanic source. The presence of the double stratification could have important implications on satellite retrievals, which usually consider only one plume layer. This work gives new details on the main features of volcanic plumes produced during low intensity and long-lasting volcanic plume emissions.

Highlights

Etna is one of the most active volcanoes in the world, characterized by frequent eruptive activity from summit craters (NEC = Northeast crater, VOR = Voragine, BN = Bocca Nuova, SEC = Southeast Crater, NSEC = New Southeast Crater (Figure 1)) and from fractures opened on volcano flanks [1]
The camera detects the column height above the summit craters while the Lidar probed the volcanic plume above Catania, 25 km away from the volcanic source
Differences were within the experimental error of the visible calibrated camera (±0.5 km), the volcanic plume slightly decreased in altitude along its path

Summary

Introduction

Etna is one of the most active volcanoes in the world, characterized by frequent eruptive activity from summit craters (NEC = Northeast crater, VOR = Voragine, BN = Bocca Nuova, SEC = Southeast Crater, NSEC = New Southeast Crater (Figure 1)) and from fractures opened on volcano flanks [1]. Those fissures are related to the emplacement of dikes diverging from the central conduit or, more rarely, directly from the main magma chamber [2]. Strombolian activity from the BN crater had variable intensity up to 28 December when it stopped late in the afternoon

Methods

Results

Conclusion