Review of Submarine Eruptions in El Hierro Prior to Tagoro

Hydrovolcanism, resulting from the interaction of magma with water, is a frequent volcanic process found in many geotectonic settings and fundamental in the growth of oceanic islands. Examples of shallow to intermediate-depth hydrovolcanic activity are frequent in the Canary Islands and characterise volcanism from the seamount stage and emergent island stage to historical volcanism. We present a review of the existing information on subaqueous shallow and intermediate-depth hydrovolcanic eruptions on El Hierro prior to the 2011–2012 Tagoro hydrovolcanic eruption. New information is provided based on the study of subaerial and intermediate-depth volcanic deposits, as well as on the analysis of possible historical submarine eruptions. Our findings show that there is evidence of several shallow and intermediate-depth submarine eruptions around El Hierro Island, some having occurred in historical times. Knowledge of these eruptions is essential not only to better understand the evolution of the island, to establish future coastal and submarine eruptive scenarios, but also to improve volcanic risk analysis. This work highlights the fact that, when dealing with volcanic islands, it is essential to include not only the coastline as a boundary, but also to consider the subaerial and submarine part of the islands in a continuous fashion, always taking into account sea level changes in the past as well as in the future.