The coastal towns of Licantén, Maule Region, Chile, were affected by a magnitude 8.8 Mw earthquake on February 27, 2010, followed by a tsunami that caused significant damage and changes in the shoreline position, marking a clear before-and-after point due to this major seismic event. Since 2015, coastal storms have increased in frequency and intensity, exposing these towns to flood risks. Using satellite imagery from Landsat 5 TM, Landsat 7 ETM+, Landsat 8 OLI, Landsat 9 OLI, Sentinel-2A/B, the CoastSat algorithm, ERA5 data, in situ data, and high-resolution Maxar images complemented by UAV flights, this work aims to determine urban expansion rates in areas exposed to tsunami flood risks defined by the Hydrographic and Oceanographic Service of the Navy (SHOA); calculate coastal erosion rates; and analyze extreme wave events in the study area. The results show that urban expansion has increased in areas affected by the 2010 tsunami, such as Iloca (36.88%), La Pesca (33.34%), and Pichibudi (20.78%). A 39-year reconstruction of the shoreline position (1985–2024) was carried out, serving as a basis to determine erosion rates and quantify shoreline dynamics. This dynamic is influenced by local water surface elevation, due to a combination of local tide variations, coastal storms, and wave-induced configurations. Erosion rates in Iloca and Pichibudi showed significant differences after the event, with rates varying from +0.94 m/year to -1.39 m/year in Iloca, +0.39 m/year to +0.47 m/year (erosion located in the distal zone) in La Pesca, and +0.42 m/year to -3.48 m/year in Pichibudi. These results highlight the lack of regulations and urban planning in areas exposed to extreme events, showing neglect in urban development and the absence of governmental action to build resilient coastal communities in the face of climate change.