Earthen construction in Costa Rica developed mainly from the first colonial settlements. Adobe and wattle-and-daub (bahareque) buildings are found throughout the country, from urban centers such as Cartago, Heredia and Santo Domingo, to areas of the North Pacific such as Liberia. However, after the 1910 earthquake in Cartago, adobe construction was banned due to the widespread destruction that the earthquake caused in the center of this province. Despite this, more than 100 years later, many of these buildings are still preserved in the country and are part of the historic urban landscape. Since 2024, the Costa Rica Institute of Technology (Instituto Tecnológico de Costa Rica) has been developing the “Seismic Earth” project. Among its objectives is working on a first record of the earthen buildings of the urban centers of Cartago and Santo Domingo, identifying the particularities of the construction techniques used, and making a comparison between the buildings of both territories, creating a digital cartography and a WEB MAP that compiles the main findings by zone, one that is highly affected by seismic activity and another that is not. Among the first results, it was found that the substitution of buildings and the transformation of the historic center of Cartago are evident, where a minimum number of wattle-and-daub buildings remain, while in the historic center of Santo Domingo, adobe constructions predominate and there are approximately 110 buildings featuring this construction system. The first stage of the research shows significant differences in the persistence of construction techniques and although the hypothesis can be associated with the direct impact of the seismic event and the transformation of the building stock, a second stage will deepen the study of the composition of the materials to characterize the construction systems used.