Detecting cyclic behaviour at calcalkaline volcanoes: the case of Fuego de Colima (Mexico) and Santiaguito lava dome complex (Guatemala)

Abstract:

In the last decades the investigation on the cyclic activity at dome volcanoes has improved with the availability of the satellite thermal data for observing volcanic activity, combined with numerical modeling and geophysical studies. Using these approaches, we studied the secular fluctuations in the magma discharge rate at Santiaguito lava dome complex (Guatemala) during 1922-2019 and the eruptive style transitions at Fuego de Colima volcano (Mexico) during the last twenty years. For both case studies we reconstructed the yearly, monthly and weekly discharge rate averages, combining the MODerate resolution Imaging Spectroradiometer (MODIS) data and published observational ones. By using spectral and wavelet analyses, we detected a multiyear long-term, multi- month intermediate-term, and multi-week short-term cyclic behavior during the period of the two investigated eruptive activities, which show similarities to those of many other dome-forming volcanoes. We provided numerical simulations to investigate their nonlinear cyclic eruptive behaviors considering a magma feeding system composed of a dual or a single magma chamber(s) connected to the surface through an elastic dyke developing into a cylinder conduit in the shallowest part. By exploring cases in which the periodicity is controlled by (i) the coupled deep–shallow magma reservoirs, (ii) the single shallow chamber, and (iii) the elastic shallow dyke when it is fed by a fixed influx rate or constant pressure, we reproduced the long-, intermediate- and short-term periodicities in discharge rates as revealed by thermal data. Coupling spectral analyses and numerical modeling, we inferred a first-order picture of the Santiaguito and Fuego de Colima feeding systems, giving new insights to improve our comprehension of the eruptive behavior of andesitic volcanoes.