How long-term hazard assessment may help to anticipate volcanic eruptions: The case of La Palma eruption 2021 (Canary Islands)

Abstract

Long-term hazard assessment is an essential action that should be undertaken at all active volcanoes and/or volcanic areas as an indispensable contribution to reduce volcanic risk. It allows anticipating new eruptions responding to two of the main questions of volcano forecasting: where and how the next eruption will be. In the case of the Canary Islands, an active volcanic region that receives millions of visitors every year, and which has been recently severely impacted by a small size eruption on the island of La Palma in 2021, a systematic long-term hazard assessment is still pending, despite this being foreseen in its management plan to face volcanic threats. An essential basic long-term volcanic hazard assessment, conducted six years before this last eruption, was able to anticipate the location of the new vents and the eruptive style, including the extent of its main potential hazards. This long-term research was developed in the frame of a Master thesis, which was aimed at justifying the viability of a particular systematic long-term volcanic assessment methodology to be applied to the Canary Islands and elsewhere. Despite this particular study was not used to manage the La Palma 2021 eruption, it demonstrates how beneficial such studies may be to forecast new eruptions and to reduce their associated risk, and represents a new contribution to develop adequate territorial and management planning where we provide a qualitative hazard map for the Island of La Palma.