The 1730-1736 Eruption of Lanzarote, Canary Islands

Abstract

Eruptions resumed in 1730 in Lanzarote Island after a prolonged period of volcanic repose, probably encompassing the entire Holocene. This historical eruption involved about 3–5 km3 of basaltic pyroclasts and lavas, covering some 225 km2 (one third of the island). The accumulation of volcanic products had a strong impact on the landscape of this Miocene oceanic island. This was the second largest effusive basaltic event in recorded history, surpassed only by the 1783 Lakagigar eruption in Iceland. The central part of Lanzarote was mantled by lapilli-derived soils and aeolian sands, which provided a strongly contrasting ground for the basaltic products of the 1730 eruption. After the initial phase of the eruption, the style changed and new vents were controlled by a 15-km-long volcano–tectonic zip-like eastwards-progressing fissure, with the first vents opening offshore west of the island. This abrupt modification may explain the progression of this eruption, from the average duration of historical Canarian eruptions (a few months), towards an exceptionally prolonged period of about six years. Besides duration, other outstanding features of the 1730–1736 eruption include the tholeiitic composition of lavas and the length of flows and lava tubes, particularly in the final stages. Initially, the eruption had a catastrophic impact on the resources of the island, since most of the farmland was covered by lavas and lapilli. However, agriculture significantly improved after the eruption with the introduction of dry farming, using lapilli cover as a new mulching technique.