Evaluation of secondary effects after the January 18, 2021, Mw 6.5 earthquake in San Juan, Argentina: determination of the seismic intensity through the ESI-2007 scale

Abstract

This study focuses on evaluating the numerous secondary effects, such as mass wasting and soil liquefaction, caused by the Mw 6.5 earthquake that occurred on January 18, 2021, in the province of San Juan, Argentina. The epicenter was located on the eastern flank of the Las Osamentas range. Although it caused significant damage to buildings and cultivated areas, there were no fatalities. The aim is to identify and describe these secondary effects and determine the seismic intensity of the event using the INQUA’s (International Union for Quaternary Research) 2007 ESI (Environmental Seismic Intensity) scale. Field assessments were conducted shortly after the earthquake, documenting liquefaction and mass wasting structures through direct observations, digital photographs, GPS (Global Positioning System) localization, and data inventory, among other methods. This procedure validates a protocol for future applications in estimating seismic intensities for sparsely populated areas. Additionally, the study seeks to confirm the scientific and cultural importance of these ephemeral structures as assets that could be protected, therefore contributing to regional development.