Syn-Eruptive Lateral Collapse of Monogenetic Volcanoes: The Case of Mazo Volcano from the Timanfaya Eruption (Lanzarote, Canary Islands)

Abstract

The evolution of complex volcanic structures usually includes the occurrence of flank collapse events. Monogenetic cones, however, are more stable edifices with minor rafting processes that remove part of the cone slopes. We present the eruptive history of Mazo volcano (Lanzarote, Canary Islands), including the first detailed description of a syn-eruptive debris avalanche affecting a volcanic monogenetic edifice. The study and characterization, through new geological and morphological data and the analysis of a great number of documentary data, have made it possible to reinterpret this volcano and assign it to the Timanfaya eruption (1730–1736). The eruptive style evolved from Hawaiian to Strombolian until a flank collapse occurred, destroying a great part of the edifice, and forming a debris avalanche exhibiting all the features that define collapsing volcanic structures. The existence of blocks from the substrate suggests a volcano-tectonic process associated with a fracture acting simultaneously with the eruption. The sudden decompression caused a blast that produced pyroclasts that covered most of the island. This study forces to change the current low-hazard perception usually linked to monogenetic eruptions and provides a new eruptive scenario to be considered in volcanic hazards analysis and mitigation strategies development.

Las Cabras volcano, Michoacán-Guanajuato Volcanic Field, México: Topographic, climatic, and shallow magmatic controls on scoria cone eruptions

“…At Paricutin, the main cone was breached numerous times during the early eruptive period, each of these events associated with rapid increases in lava outflow (Foshag and González-Reyna, 1956). Nevertheless, there are examples where the cone sector collapse seems to be unrelated to lava emissions (Tibaldi, 1995), such as the one described in detail at a historic, 180 m-high cone in Tenerife (Romero et al, 2021). In this latter case, the processes involved and the resulting deposits closely resemble those associated with collapse at stratovolcanoes, with faulting as a trigger, and ensuing violent explosive activity (Romero et al, 2021).…”

“…Nevertheless, there are examples where the cone sector collapse seems to be unrelated to lava emissions (Tibaldi, 1995), such as the one described in detail at a historic, 180 m-high cone in Tenerife (Romero et al, 2021). In this latter case, the processes involved and the resulting deposits closely resemble those associated with collapse at stratovolcanoes, with faulting as a trigger, and ensuing violent explosive activity (Romero et al, 2021). At Las Cabras, deep cuts into the lavas are largely absent and posteruptive weathering and anthropic activities (e.g., agriculture) have modified the surface hiding lithologic contacts.…”

Volcanic Lateral Collapse Processes in Mafic Arc Edifices: A Review of Their Driving Processes, Types and Consequences

“…The rafts are made of bedded fragments from the intact cone, partially disintegrated agglutinate deposits or loose pyroclastic debris blanketed by scoria fallout (Valentine et al, 2006) as clearly seen in Marcath volcano (Figure 3F; Valentine et al, 2017). If sudden, a small scale flank failure of the cone portion may cause the unloading of the shallow plumbing system, producing a change in the eruption style (e.g., enhancing explosivity), as seen in Los Morados scoria cone (Figure 3G; Argentina, Németh et al, 2011) or the Timanfaya eruption (1730-1736) at Mazo volcano (Canary Islands) which triggered a small directed blast as well as forming a debris avalanche deposit covering 1,218 km 2 and extending 1.6 km from the vent (Romero et al, 2020a).…”