Seismic risk zonation in the urban development of the Andorra Valley, Ushuaia, Tierra del Fuego (Argentina)

Abstract

The city of Ushuaia is located within tectonic valleys at the southern end of the Andes Mountains, carved into schists, phyllites, and slates, whose landforms are associated with glacial processes that occurred during the Pleistocene. The urban area lies approximately 30 km south of the Magallanes-Fagnano Fault System, the main seismogenic source in Tierra del Fuego. The city has experienced significant population growth, leading to a large number of buildings that do not comply with the seismic resistance standards of the National Institute for Seismic Prevention (INPRES).
This study presents the seismic risk zoning and its components for the Valle de Andorra neighborhood, located northeast of the city, based on geological, geomorphological, and geophysical information, as well as on the assessment of buildings and their distribution, in order to determine the exposure and vulnerability of the population. The neighborhood is mainly built on moraines and glacilacustrine deposits, which have geotechnical characteristics that favor seismic wave amplification. Furthermore, houses in the peripheral areas are exposed to mass-wasting processes.

The results show that 89% of the neighborhood falls within moderate to high-risk zones, and public institutions such as schools, police stations, and health centers are located in high and very high-risk areas. This work highlights the importance of geological risk zoning in vulnerable populations and aims to present results that can be applied to local urban planning and methodologically replicated in other regions.