Precursors to intra-eruptive reposes during the 1998–2019 lava dome-building eruption at Volcán de Colima, México

Abstract

The 1998–2019 lava dome-building eruption at Volcán de Colima, México, involved two eruptive cycles of activity during which andesitic lava domes were extruded. The first cycle of extrusion lasted from November 1998 to June 2011 and was followed by a period of intra-eruptive repose from June 2011 to January 2013. The second cycle lasted from January 2013 to March 2017. The second intra-eruptive repose began from March 2017, and continues through the time of writing (April 2019). The reposes were preceded by interruptions in the endogenous regime of growth of the lava domes by extrusion of exogenous shear lobes (before repose 1) and by collapse of the lava dome (before repose 2). We conclude that interruptions in endogenous lava dome growth may herald the onset of intra-eruptive repose periods at this volcano. The nature of such precursors is potentially associated with the process of batch supply from deep magma storage into the shallow system feeding the eruption. During the two cycles of eruption at Volcán de Colima, the equal volumes of products (about 75 × 10⁶ m³) were erupted with a difference in the mean magma discharge rates (approximately 5 × 10⁶ m³ and 18 × 10⁶ m³ per year for cycles 1 and 2 respectively). It seems that a cycle was controlled by a volumetric limit of 75 × 10⁶ m³; once this volume has been erupted, then the cycle ends irrespective of discharge rate. At the same time, a difference in the mean magma discharge rates may be a reason for differences in the type of interruptions.