External authors:

• Nicolas Perez-Estay ( Universidad de Chile )
• Javiera Ruz-Ginouves ( Pontificia Universidad Catolica de Chile , University of Otago )
• Pamela Perez-Flores ( Consultoria & Invest Geol Ambiental Ltd )
• Gerd Sielfeld ( University of Auckland , Cirrus SpA )
• Tomas Roquer ( Pontificia Universidad Catolica de Chile , Universidad de Chile )
• Pamela Perez-Flores ( Consultoria & Invest Geol Ambiental Ltd )
• Pamela Perez-Flores ( Consultoria & Invest Geol Ambiental Ltd )

Abstract:

Decoding means decrypting a hidden message. Here, the encrypted messages are the state of stress, fluid pathways, and volcano tectonic processes occurring in volcanoes of the Andean Southern Volcanic Zone (SVZ). To decode these messages, we use earthquake focal mechanisms, fault slip data, and a Monte Carlo simulation that predicts potential pathways for magmatic and hydrothermal fluids. From this analysis, we propose that SVZ volcanoes have three end-member stress patterns: (i) Stress-A, a strike-slip regime coupled with the regional far-field tectonic stress; (ii) Stress-B, an extensional regime that may be promoted by volcanic edifice loading and upward pressure due to magma inflation occurring within the upper brittle-crust; and (iii) Stress-C, a local and transient fluid-driven stress rotated similar to 90 degrees from Stress-A. Notoriously, Stress-C pattern was observed in most volcanoes with historical eruptions. We propose that volcanoes presenting Stress-B are attractive geothermal targets, while Stress-C could be used as a predicting signal for impending eruptions.