Diffuse Degassing Baseline in Parícutin volcano and Michoacán-Guanajuato monogenetic volcanic field, México

Diffuse CO2 emissions are a powerful tool for detecting changes in volcanic activity, temporary degassing variations, and delimiting spatial structures of fluid rise given permeability contrasts. In this work, base degassing values of CO2 flux and total fluxes are reported for the first time in the Michoacán Guanajuato monogenetic volcanic field, as well as its temporal evolution, comparing data from 2006, 2009, 2011, 2012, and until 2020 in 30 measurement stations that have the Parícutin volcano as the central zone. Likewise, diffuse degassing alignments are reported in the directions SW-NE and (SW-W) - (NE-E) in the northeast part of the Tancítaro volcano. This area coincides with the high density of earthquakes during the 2020 and 2021 swarms and with the region where La Escondida is located, whose inhabitants reported perceiving the swarm. Additionally, diffuse degassing results of CO2 are shown for the first time in Parícutin volcano, the youngest cone in the field, for three field works done in 2011, 2012, and 2020. Fluxes of CO2 remain in the range of 0.01–226.12 ± 10 g m−2 d−1. The study includes generation of distribution maps and the discussion of main diffuse degassing structures at Parícutin volcano in the directions N-S to SW-NE. Furthermore, for both zones, the entire field and the Parícutin volcano, three degassing groups (A - low, B - medium and C- high) were obtained, delimiting the anomalous degassing group in volcanic field as all CO2 fluxes with values equal or greater than group C of the Parícutin volcano (2020) in the range of 88–190 ± 10 g m−2 d−1. With this work, it is shown that the continuous measurements of diffuse emissions should be a priority of the comprehensive monitoring of the volcanic field, being able to detect in advance: (a) anomalous emissions or areas of high permeability that could favor the rise of fluids and melts; and (b) changes in the emission rates.