On data reduction methods for volcanic tremor characterization: the 2012 eruption of Copahue volcano, Southern Andes

• Published in: Earth, planets, and space planets, and space, 2020-09, Vol.72 (1), p.1-10, Article 134
• Main Authors: Melchor, Ivan, Almendros, Javier, Carniel, Roberto, Konstantinou, Kostas I., Hantusch, Marcia, Caselli, Alberto
• Format: Article
• Language: English
• Subjects: 5. Volcanology; Copahue volcano; Data reduction; Data reduction method; Earth and Environmental Science; Earth Sciences; Entropy; Express Letter; Geology; Geophysics/Geodesy; Measurement; Noise; Observations; Permutation entropy; Permutations; Phreatic eruption; Phreatomagmatism; Polarization; Polarization degree; Seismic waves; Tremors; Understanding phreatic eruptions - recent observations of Kusatsu-Shirane volcano and equivalents; Volcanic activity; Volcanic eruptions; Volcanic tremor; Volcanoes
• ISSN: 1880-5981; 1343-8832; 1880-5981
• DOI: 10.1186/s40623-020-01270-7

Improving the ability to detect and characterize long-duration volcanic tremor is crucial to understand the long-term dynamics and unrest of volcanic systems. We have applied data reduction methods (permutation entropy and polarization degree, among others) to characterize the seismic wave field near Copahue volcano (Southern Andes) between June 2012 and January 2013, when phreatomagmatic episodes occurred. During the selected period, a total of 52 long-duration events with energy above the background occurred. Among them, 32 were classified as volcanic tremors and the remaining as noise bursts. Characterizing each event by averaging its reduced parameters, allowed us to study the range of variability of the different events types. We found that, compared to noise burst, tremors have lower permutation entropies and higher dominant polarization degrees. This characterization is a suitable tool for detecting long-duration volcanic tremors in the ambient seismic wave field, even if the SNR is low.