Identification of buildings in Panama's Old Quarter (Casco Antiguo) with resonance potential during earthquakes

Panama’s Old Quarter, the Casco Antiguo of Panama (CAP), is renowned for its historical and architectural value. Protecting this UNESCO World Heritage site requires research sensitive to its distinct geological and structural features. This study aims to identify buildings within CAP that may be susceptible to soil-building resonance effects, which can amplify structural responses during earthquakes if the fundamental periods of the soil ( T g ) and buildings ( T 1 ) align. To determine T g and T 1 , ambient noise (microtremors) measurements were conducted using a portable seismometer in free-field areas (12 sites) and selected buildings (38 structures). The data were analyzed using spectral ratio techniques: horizontal-to-vertical (H/V) for soils and top-to-base horizontal component ratios (H i /H 0 ) for buildings. T g values were used to create a microzonation map, which showed mostly low T g values indicative of stiff soil in the area. An equation was developed to estimate fundamental periods for unmeasured buildings. This allowed for a comprehensive map of T 1 across CAP. Most buildings, predominantly low-rise masonry, exhibited low T 1 values. By overlaying the T g and T 1 maps, buildings at risk of resonance effects were identified, with approximately 5 % classified as having a high potential of resonance. These buildings could experience amplified structural responses, suggesting an elevated seismic risk.