Hazard exposure ranking for population centres in the Central Andes of Chile and Argentina

DANIEL BERTIN; JAN M. LINDSAY; SHANE J. CRONIN; DE SILVA, SHANAKA; CHARLES B. CONNOR; PABLO J. CAFFE; PABLO GROSSE; WALTER BAEZ; EMILCE BUSTOS; ROBERT CONSTATINEUCU

Congreso; Cities on Volcanoes 12; 2024

In this contribution, we present a volcanic hazard exposure ranking developed for 692 settlements in the Chilean-Argentinian Central Andes (~22.5-29°S). This is an arid, high-altitude, and remote area, mostly characterized by small rural communities, commonly exposed to climate-related hazards such as flash floods, draughts, blizzards, and dust storms. Volcanic hazards have usually been overlooked due to the remoteness of the region and the relatively low eruption frequency when compared to other volcanic arc segments. However, recent research has identified younger-than-expected (~4.2 ka BP), large-magnitude (VEI 6+) explosive eruptions as well as other Holocene activity, including some centuries-old tephra deposits from unknown sources. We developed and tested a methodology that probabilistically quantifies the volcanic hazard of this 300,000- km2 region by integrating its spatial, temporal, and volumetric volcanic record. Our analysis was based upon a new geospatial database that compiles the last ~35 Myr of volcanism. We generated probabilistic hazard maps for flow and fall processes, which were later integrated into a single map. In this way, we were able to identify, for the first time, order-or-magnitude variations in volcanic hazard across the region. The integrated hazard map was used to calculate the relative hazard of all settlements in the region, which were then ranked accordingly. Touristic towns such as Talabre, Socaire and Antofagasta de la Sierra, El Peñón, and Toconao rank high in our study. These results can be useful for prioritizing hazard mitigation actions or more detailed location-specific risk analysis, enabling the targeting of limited resources for new investigations.