Deformation of Popocatépetl volcano using GPS: Regional geodynamic context and constraints on its magma chamber

We have operated a GPS network on Popocatépetl volcano since 1994 consisting of a total of 7 continuous GPS stations on its northern and southwestern flanks and one additional station in the vicinity of the volcano. The overall characteristic behavior of Popocatépetl volcano during this period can be described as a minimally deforming system, in sharp contrast with its essentially continuous visible eruptive activity. A north-component motion analysis, assuming a fixed North American plate, shows a close correspondence of the Popocatépetl sites to those of other regional GPS sites. Most of the large-deformation transients observed on the Popocatépetl sites are therefore not of magmatic origin, but instead reflect aseismic transients that have been recognized recently as part of the Mid-American Trench subduction process. The surface deformation record of Popocatépetl volcano therefore suggests a magmatic system that lacks a well-defined shallow magma chamber, where most of the magma storage, transport, and ascent is carried out via a network of deep-rooted conduits that eventually extend to the summit crater. In most cases, Popocatépetl seems to operate as a semi-open system, thereby preventing any significant pressure build-up.