Geological map at 1:12,500 scale of the western sector of El Hierro Island (Canary Archipelago)

Abstract

El Hierro, the youngest and smallest island in the Canary archipelago, has active magmatism that poses a potential hazard, evidenced by historical volcanic events such as the 1600 Lomo Negro eruption and the 2011–2012 submarine eruption off its southern coast. Despite extensive geological studies, a detailed geological map of the island was lacking until recent work. This study

provides the first detailed geological map of the western sector of El Hierro (approximately 90 km2 ) at a 1:12,500 scale, developed from a geological survey conducted in 2022. Over 100 lava flows were identified and their directions measured, revealing stratigraphic relationships that allowed identifying formations and members and subsequently grouping them in four volcanic stages: Roque del Julan, Morro del Paso, El Jaral, and La Frontera. The study also estimates the minimum erupted volumes of over 70 lava flows. Key findings indicate that El Golfo collapse, a significant event in the island’s volcanic history, led to an increased eruption frequency, but a reduction in individual eruption volumes. Additionally, the study highlights a spatial migration of eruptive fissures toward the island’s outer regions post-collapse, while eruption fissure orientations remained unchanged. These findings are crucial for understanding volcanic hazards and recurrence intervals on El Hierro.