Instituto Geográfico Nacional Volcano Monitoring of the 2021 La Palma eruption (Canary Islands, Spain)

The monitoring of the anomalous signals associated with the ongoing magmatic process occurring in La Palma, and their interpretation, allowed the proper forecast and management of the last eruption in the Canaries. This eruption occurred 10 years after the submarine eruption in El Hierro island (Tagoro, 2011) and 50 years since the last eruption in La Palma island (Teneguía, 1971). The early signs started in October 2017 and lasted until 2021, with the occurrence of 7 short lasting seismic swarms located at depths between 20-30 km, below Cumbre Vieja volcanic edifice (the volcanic active zone of the island during the last 125 ky). Also, during this period, several geochemical signals were registered associated with the emplacement of magma below the island and the local changes of stress. The eruption was preceded by 1 week (September, from the 11^th to the 19^th) of strong unrest, with seismic activity (shallower than the previous swarms) and surface deformations. Data registered by the IGN volcano-monitoring network, were transmitted, processed and interpreted in real time, and have been essential to the management of the volcanic crisis, providing the Canarian Civil Protection with valuable scientific information to undertake the preventive actions in each phase of the crisis in order to mitigate its effects. Data and samples collected (lava, ashes, water, gases) will allow to identify the causes and mechanisms of this eruption and will shed light on the origin of the magmatism in the Canaries.