A study by researchers at the Andes Center of Excellence in Geothermal Energy (CEGA) in Chile has proposed a geoscientific model for classifying volcanoes in the Southern Andean Volcanic Zone (SVZ). Through this research, two volcanic complex and five volcanoes were identified as having potential for high-enthalpy geothermal energy production.
The paper “Decoding the state of stress and fluid pathways along the Andean Southern Volcanic Zone” by Pérez et al has been published in the journal Communications Earth & Environment.
The South Andean Volcanic Zone
The SVZ runs through central to southern Chile and is characterized as having some of the most active volcanoes in the region. Although the SVZ and its volcanoes are well described in the literature, little is known about what happens beneath them: how the magmas flow, what types of stress they are accumulating and what are the underlying tectonic processes that govern their movements.
To characterize these volcanoes, the researchers conducted field expeditions and complemented their efforts with a review of previous studies on seismology and structural geology of the SVZ to develop physical-mathematical models and simulations to categorize the volcanoes based on behavior patterns.
“One of the biggest challenges in volcanology is detecting patterns. Volcanoes are rebellious structures, each with its own traces, markers and signals, which makes them difficult geological structures to study. In this context, the use of categories is complex, but at the same time, necessary,” said Dr. Nicolás Pérez , researcher at CEGA and lead author of the study.
Three categories identified
Three patterns – Type A, Type B, and Type C – were identified by the paper. Of the three, Type B volcanoes were cited as those that would have the highest potential for high-enthalpy geothermal exploration. These volcanoes are characterized by having a magmatic chamber at relatively shallower depths (less than 10 km) which would favor the circulation of magmatic and hydrothermal fluids in the subsoil.
Type B volcanoes include the San Pedro-Tatara volcanic complex, the Puyehue-Cordon Caulle volcanic complex, and the Copahue, Caviahue, Tinguririca, Tolhuaca, and Mentolat volcanoes.
“The pressures required to generate fractures or channels that allow the circulation of hot fluids are the lowest in type B volcanoes, which makes them good candidates for geothermal production,” said Dr. Pérez.
On the other hands, Type A volcanoes are produced by tension at the contact between the Nazca and South American plates, while Type C volcanoes could be related to ancient faults oblique to the arc. Type C volcanoes are also the most active based on historical records, accounting for more than 90% of the historical eruptions recorded in the last 300 years have occurred in this type of volcano.
A global implication
The research paper states that the results presented are based on the currently available information, but more type B volcanoes may be identified if more data is presented. It also notes that the stress patterns identified in the study are not limited to the Southern Chile Volcanic Zone. The Type A pattern, for instance, has been described in specific volcanic arcs in Japan, Indonesia, and the United States.
“There are few studies on regional stress regimes in volcanic arcs around the world. These studies are important not only for their implications in Chile, but also because these models could be used in other parts of the world,” concludes Dr. Pérez.
Source: Universidad de Chile
The post CEGA research proposes volcano classification to aid geothermal prospecting first appeared on ThinkGeoEnergy – Geothermal Energy News.