Lava flow growth inferred from morphometric parameters: a case study of Citlaltépetl volcano, Mexico

Abstract

Recent (Quaternary) lava fields, such as those of Citlaltépetl (Pico de Orizaba) volcano in Mexico, are excellent places to obtain precise measurements of flow-field dimensions that can be used to estimate volume, eruption duration and effusion rates. The relationship between these parameters and the influence of some other interrelated features such as lava composition, superficial structures and lava type are important tools that can help to infer conditions when the lavas were active and thus improve understanding of how flow fields grow. The Holocene lavas of Citlaltépetl volcano are homogeneous in composition (dacites) and are generally blocky with well-developed levees. The eruption duration obtained for the Citlaltépetl lavas by a method proposed by C. Kilburn and R. Lopes presents a good correlation with the different lava types morphologically classified here. Results from that method compare favourably with the inferred effusion rates estimated by an empirical cooling method (Graetz). The lavas show different behaviour, mainly controlled by fluctuations in the effusion rate that promote changes from single- to multiple-flow style. The maximum distance achieved by a flow is directly proportional to the effusion rate in Citlaltépetl lavas, but it is always lower for multiple flows, independent of the volume of erupted lava. Observations of Citlaltépetl lavas can be used to understand how lava flow growth occurs on other volcanoes.