LAMAS

Large scale intrusion, lateral magma reservoir growth and stress field changes at Lazufre volcano, Chile

Project duration: 2009-2013
Deutsche Forschungsgemeinschaft DFG
PI: Thorsten Dahm, Thomas R. Walter, Dennis Legrand

Collapsed calderas are the morphological and structural surface expression of magma reservoirs that emptied during large volcanic eruptions and may reach diameters of tens of kilometers. Abundant remnants of such collapse calderas can be found, e.g. along the South American volcanic arc; though often thought to be inactive nowadays. The geometric, temporal and dynamic development of large crustal magma reservoirs with scales of 30 or more kilometers, underlying collapse calderas, are poorly understood. New satellite radar interferometry (InSAR) studies, however, suggest that magmatic systems of such dimension may develop in a short time period without attracting much attention. In northern Chile, a 45 km wide elongated area of ground deformation is found at Lazufre, which is an area where no deformation was detected 10 years ago. This example allows for the first time to investigate the source geometry of a large-scale Andean magma reservoir at unprecedented detail, with the aim to understand how the large magma body may have accumulated within a few years only, and to investigate the effects and causes of the local and regional stress field. The principal investigators of this proposal have already conducted a two-months seismological field campaign in a Chilean-German collaboration, which now provides the data background to further elaborate the development, dimension and physics of this awakening volcano system. Herein we apply for funding (a) to conduct a detailed investigation of the seismological data, the reservoir structure and induced seismicity and (b) to integrate seismicity with time-series of InSAR deformation data, and to develop numerical models that aim to analyze and simulate the intrusion and the associated stress field. The main goal is to obtain a better understanding of the intrusion system and its recent changes and to develop a principal mechanical model evaluating also stress changes that can serve to analyze other similar system elsewhere.