Influence of meteorology on the variations of crustal seismic velocity in Volcan de Colima, Mexico using Noise Interferometry

The temporal variation of seismic velocity gives us information about the crust’s stress state and the relative changes associated with magmatic, tectonic, and meteorologic activity. In the present study, we analyze the temporary seismic velocity changes under Volcan de Colima to identify its relationship with volcanic and non-volcanic sources, evaluate the seasonality of the variations and describe the impact that the meteorology has on the changes. The signals of seismic velocity variation used in this work were measured using the single-station cross-component correlation technique applied to traces registered at four stations in the period 2013 – 2017. The data was analyzed in two frequency bands: 0.1 – 1 and 1 – 2 Hz.

We validate the relationship between the velocity variations and three meteorological parameters, rain, temperature, and atmospheric pressure, using wavelet coherence analysis. After fitting a linear model, we identified the environmental factors with the most impact on the seismic velocity are: 1) the rainfall-induced pore pressure, correlated negatively with the seismic velocity and causing changes close to the order of -0.5%; 2) thermoelastic strains correlated positively with the seismic velocity and causing velocity variations between -0.5 and 0.5%. Atmospheric pressure has a smaller impact, mainly of the order of 10^-3%.