Seismic velocity structure of Popocatépetl volcano, Mexico from diffusive fields

Abstract

Since its reactivation in 1994, several geophysical studies have been performed to understand the eruptive history, volcanic activity, and associated hazards of the Popocatépetl volcano. Many studies characterized the volcano-tectonic seismicity that has been used to generate velocity models of the volcano. However, the proposed models are not sufficiently resolved to describe patterns in a large area or depth range because of the spatial distribution of the seismicity and stations used. In this work, we propose the first 3D velocity model of Popocatépetl volcano describing the whole edifice inverting group velocity dispersion curves obtained from ambient noise cross-correlations using data recorded at 39 broadband seismic stations installed in different epochs. To increase the information for the modeling, we computed the CC function using two methods. Our results suggest the presence of a mushroom-shaped Popocatépetl's magmatic system composed of two high Vs regions at 0–5 km a.s.l and 4–7 km b.s.l connected by a narrow ‘pipe-like’ conduit. The shallow high Vs region is directly related to old and young volcanic structures as a result of mixed magmatic materials that are affected by an intense degassing process that increases the magma viscosity and crystal content. The deepest high Vs region is interpreted as magmatic material stagnated by lithostatic pressure. Moreover, the model presented here reveals evidence of buried volcanic paleo-structures and the remains of ancient collapses of the volcano.