Aeromagnetic survey of los Humeros Caldera, México

Abstract

A regional aeromagnetic survey over Los Humeros Caldera, Puebla, Mexico, reveals a magnetic anomaly of bipolar character over the central part of the caldera. This large anomaly is interpreted in terms of a prism whose depth to the top is 2 km with horizontal dimensions of 5 km x 2 km. The prism-like, highly magnetized, intrusive plug underlies the central part of the collapsed structure. Other smaller anomalies occur over and around the rim of the caldera. The high contrast between the effective intensity of magnetization of this intrusive, volcanic prism and the superficial volcanic flow is of the order of 16 x 10ᵌ cgs units, which is in agreement with effective magnetization determinations over Hawaiian, Japanese and other volcanoes, as obtained from the analysis of aeromagnetic data. Interpretation of the aeromagnetic data of this caldera implies that magma is unlikely to exist shallower than 7 km in depth. However, a temperature below, but close to, the Curie point is possible at depth, which may render such an intrusive of geothermal interest.