Secondary pyroclastic cones created by syn-eruptive wind

Mafic eruptions and their associated lava fountains are a widespread form of volcanism on both Earth and other planets. These eruptions typically produce scoria and spatter cones, or hybrids of the two, and both the characteristics of the associated tephra blanket and the morphology of the pyroclastic cone can forensically provide quantitative information about the eruption conditions. However, the morphology of a pyroclastic cone results from a complex interplay between syn-eruptive processes (e.g., volume of magma erupted, grain size of pyroclasts produced, syn-eruptive wind) and post-formation erosional processes. Thus, to quantitatively use cone geomorphology to inform on volcanic processes, the contribution of each of these factors must be disentangled. Specifically, here, we focus on the effect that atmospheric winds have at the time of the eruption in controlling the resultant cone morphology. We investigate Volcán del Cuervo, a pyroclastic cone in Lanzarote that has a complex morphology consisting of a distinct, elongated shape, with a second accumulation of pyroclastic material adjacent to the main crater. Here, we use an unnamed aerial vehicle to acquire a high-resolution, photogrammetrically derived digital elevation model (DEM). This DEM allows us to quantify the cone morphology and the precise location of the associated pyroclastic deposits. Samples were collected and associated grain size and density measurements were performed to characterise the pyroclastic material constituting the cone. Together, these data were then used in a ballistic trajectory model to constrain the critical wind and eruptive conditions required to form a secondary cone. Through transplanetary analogies, we conclude that secondary cone formation by this mechanism may bias remotely sensed detections of eruptive centres on planetary surfaces. Misinterpretation of these cones as separate eruptive vents would lead to an overestimation of past volcanism. Correct identification of secondary cones can instead provide direct constrains on eruption dynamics and past atmospheric conditions, including prevailing wind directions—an aspect that is particularly important in planetary environments where direct field validation remains unfeasible.