Nature inspires both awe and concern. Natural processes regulate the Earth's dynamics and sustain life, but when they intersect with human populations and infrastructure, they can lead to disasters with devastating consequences. There is a delicate balance between societies and Earth’s dynamic systems. Although we cannot control natural forces, understanding them enables us to make informed decisions and navigate their challenges more effectively. At the core of the Earth system lies the Geosphere. Within it, the tectonic cycle reshapes the planet’s surface and drives volcanism, exemplifying the interconnected nature of Earth’s systems, as changes in one sphere can cascade through others. Volcanism remains one of the most powerful and unpredictable forces shaping the planet.
Disasters result from the intersection of hazards with vulnerable societies, often triggering a cycle that begins reactively with emergency response. The goal of disaster risk reduction frameworks is to shift this cycle forward in time by taking preventive actions to reduce or mitigate potential impacts. These actions rely on risk assessments that help identify hazards—in this case, natural processes produced by volcanoes—and analyze exposure, vulnerability, and resilience. Recent advances in volcanology have improved our capacity to anticipate volcanic hazards using geological records, monitoring networks, and probabilistic modeling. The analysis of hazard intensity metrics further supports the quantification of potential impacts and enables more informed decision-making and effective mitigation strategies. However, identifying the appropriate tools remains challenging, not only for the communities living near volcanoes but also for stakeholders across all levels and sectors.
This thesis investigates how humans and volcanoes can coexist more safely by transitioning from broad regional assessments to detailed localized studies, with a particular emphasis on tephra fallout. It focuses on three key areas: the identification of high-risk volcanoes in the Central Volcanic Zone of the Andes through regional mapping and a comprehensive Volcanic Risk Ranking methodology that integrates hazard, exposure, vulnerability, and resilience; the development of a multi-source, scenario-based probabilistic tephra hazard assessment in the Southern Volcanic Zone of the Andes, identifying the areas most likely to be affected by tephra fallout; and the assessment of the impact of tephra accumulation on roofs during the 2021 Tajogaite eruption (La Palma, Spain), highlighting the role of building typologies and pre-planned clean-up operations in reducing roof collapse.
Human progress depends on stability and security. Understanding the dual role of volcanism is key to developing strategies that balance its benefits with the imperative of safety. This thesis advocates that people-centered risk assessments aligned with global frameworks should be co-developed among scientists, authorities, and communities, ensuring transparent and timely information sharing throughout the risk assessment process. With practical, interdisciplinary, and proactive approaches adapted to the complexities of each volcanic context, this work hopes to contribute to building safer and more resilient volcanic territories.
