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Irazú volcano in Costa Rica is one of the most active and potentially dangerous volcanoes in Central America. Over the last 2600 years (before 1723 CE) it has experienced at least thirty explosive events of Strombolian, phreatomagmatic, and phreatic character and from different vent areas, ranging in size from VEI 1 to VEI 3, generating lava flows, lahars, non-eruptive sector collapses, and strong seismicity, even without eruptions. Recent tephrochronological data confirm that this volcano has had an eruption frequency ranging from 23 to 100 years, with a major event every 85 years. Several thousands of people live in the vicinity of the Irazú volcano, in areas that may be heavily impacted by lahars, ash falls, and pyroclastic density currents. Moreover, >2.5 million people live in the Greater Metropolitan Area, at the heart of the Costa Rica economy, located <30 km to the west of the volcano subject to the prevalent wind direction that has controlled ash fall emplacement for historical eruptions. In this contribution we conduct a long-term hazard assessment that aims to anticipate when (temporal analysis), where (volcanic susceptibility, i.e., vent location), and how (eruption scenarios) the next explosive episodes at Irazú volcano will occur. This information is essential to implement more rational territorial planning and to design better emergency plans for coping with future volcanic crises.

In Costa Rica, all the large volcanoes have been converted into national parks, which has limited human occupation and productive activities in its closest areas. The country has been promoted worldwide as an important tourist destination due to its biodiversity and commitment to conservation, increasing tourism and people's exposure to different volcanic hazards. Public universities and the National Commission for Risk Prevention and Emergency Attention (CNE) carry out informative and educational activities for the population. In 2020, the CNE promoted a ‘geoliteracy’ campaign, through the design and installation of signs with preventive and geo-educational information on volcanoes in Spanish and English. As of December 2022, more than 250 signs had been installed in collaboration with National Parks, the Costa Rican Electricity Institute, communities, private companies, the tourism sector, and the Community Aqueduct and Sewer Management Associations. These actions have generated a sense of empowerment and belonging in the actors involved. The actions are linked to the National Law on Emergencies and Risk Prevention, the National Risk Management Policy (2016-2030) and the National Risk Management Plan 2021-2025., En Costa Rica, todos los grandes volcanes se han convertido en parques nacionales, lo que ha limitado la ocupación humana y las actividades productivas en sus áreas más cercanas. El país se ha promocionado a nivel mundial como un destino turístico importante por su biodiversidad y compromiso con la conservación; aumentando el turismo y la exposición de las personas a los diferentes peligros volcánicos. Las universidades públicas y la Comisión Nacional para la Prevención de Riesgos y Atención de Emergencias (CNE) llevan a cabo actividades informativas y educativas para la población. En el 2020, la CNE impulsó una campaña de geoalfabetización, mediante el diseño e instalación de rótulos con información preventiva y geo-educativa sobre los volcanes en español e inglés. Hasta diciembre de 2022, se habían instalado más de 250 rótulos en colaboración con Parque Nacionales, Instituto Costarricense de Electricidad, comunidades, empresas privadas, el sector turístico y las Asociaciones Administradoras de Acueductos y Alcantarillados Comunales. Estas acciones han generado un sentido de empoderamiento y pertenencia en los actores involucrados. Las acciones están vinculadas a la Ley Nacional de Emergencias y Prevención de Riesgos, la Política Nacional de Gestión de Riesgos (2016-2030) y el Plan Nacional de Gestión de Riesgos 2021-2025.

The eruption of the Tajogaite volcano in 2021, in the Cumbre Vieja rift zone (La Palma, Canary Islands), is the most recent but also the most damaging and longest-lasting eruption on the island since historical records began. We analyzed geophysical parameters (seismicity, surface deformation, thermal anomalies, and volcanic activity) with the aim of reconstructing the temporal development of the magma plumbing system. The seismic sequence (> 9000 events, mbLg ≤ 5.0) can be grouped into nine distinct phases, which correspond to well-separated spatial clusters and distinct earthquake regimes. A strong premonitory thermal anomaly was calculated on July 2021 in the South of La Palma. The source of the magma was within the upper mantle (40–20 km depth). A second magma budget (< 15 km depth) indicated a short-term stagnation of alkaline magma within the lower crust, near the Moho. The outline of these earthquakes delineates the magma pathway. Just before and immediately after the eruption (phases 2 and 3), the high-frequency seismicity in the mantle disappeared completely, reappearing ten days after the eruption started. The pattern of deformation began before the eruption with a breakpoint around September 11, after which, deformation accelerated sharply, followed by stabilization in phase 3 and a decrease in the following phases. The level of deformation suggested that a shallow magma intrusion was established. Based on the historical eruptive pattern, it is possible to infer two possible hazard-forecast scenarios: (a) the volcano could enter a prolonged phase of tranquility for more than one century or, (b) a new eruption could occur between ca. 2045 and 2065, with a slightly shorter duration than this recent one. Therefore, if the more pessimistic scenario is assumed, appropriate territorial planning is required.