Structure of the Colima Volcanic Complex: Origin and Behaviour of Active Fault Systems in the Edifice

The Colima Volcanic Complex (CVC) is one of the most prominent volcanic edifices within the Tran-Mexican Volcanic Belt (TMVB). Its evolution has been characterized by complex interactions among regional tectonics, basement geometry and rheology, and successive volcanic edifices formed in several stages. In the first part of this review chapter, the state-of-the-art in the CVC structural and geological knowledge is summarized and discussed. Such knowledge is based on published structural, geological, geophysical, geodetic and petrological data and models, which allow identification of three main fault systems and definition of the general geometrical properties of the volcano plumbing system. The significance and supporting evidence for the Colima Rift faults, Tamazula Fault and volcano spreading structures, as well as their interactions with the CVC, are presented. In the second part of the paper, numerical models are performed to integrate previous knowledge and test the effects of different structural scenarios and different mechanical assumptions on the onset of gravitational spreading of the volcanic complex. Also, the state of activity of the three fault systems and their control on the magmatism and flank instability are discussed. Finally, the main findings on the CVC structural arrangement are summarized, and the most important requirements for improvement of our understanding of the interaction between regional tectonics, volcanic edifices and basement rheology are suggested. Future investigations are critical, as eruptions and sector failures represent potential high risks for more than 500,000 people.