Gravimetric Definition of the Magmatic Chambers of the Popocatépetl-Iztaccíhuatl Volcanic Complex, Mexico

Volcanic activity is a potential hazard when activity occurs near populated regions. Iztaccíhuatl (IZ) and Popocatépetl (PO) volcanoes are in the Trans Mexican Volcanic Belt, in the Sierra Nevada range, near populated areas reaching nearly 28 million people. Understanding their internal structures may help prevent catastrophic consequences. To explore the relationship between their plumbing systems we perform 3D inversions of its high-resolution, satellite-derived Bouguer anomaly, which unveils heretofore unknown relationships between them. Previous gravity analyses suggest the existence of an extensional process whose axis is along the Sierra Nevada, including the area of Mexico City to the NW, and extending beyond Malinche volcano to the SE. Different resolutions of the volume inversions help visualize the internal structures of PO and IZ. The inversion with the highest resolution shows the IZ volcano displaying two magma chambers along the N-S direction. The main magma chamber is fed vertically from deeper sources, whilst the adjacent one is apparently fed horizontally from the main one. PO’s magma chamber is not fed vertically, but at ~21° from the vertical, by the main magmatic chamber of IZ; the center of PO’s magmatic chamber is located at +1.8 km asl. The present chimney of PO is observed to deflect from the vertical, which we associate with the collapse of an ancestral volcano of PO, recognized as El Ventorrillo. The present chimney of PO drastically diminishes its cross-section 3 km asl, risking occlusion, which may lead to an explosive event. These findings agree with the seismic and geobarometric results obtained elsewhere.