Vertical growth of masonry buildings in Peru and its role in the increase of seismic vulnerability

In Lima, the capital of Peru, and many cities in South America, houses tend to grow vertically. Due to financial limitations and increment of family members, houses increase a floor at different periods. As a result, their dynamic properties and performance during earthquakes change over time. Thus, it is necessary to estimate the change in the seismic vulnerability considering the height change in time. Unfortunately, today, there is no information regarding the vertical growth rate of buildings in Lima. To this aim, we have estimated the vertical growth rate of informal masonry buildings by inspecting 457 samples. The selection of the buildings was based on their availability in the Google Street View dataset, which was used to identify the number of floors in 2013. Then, the number of floors in 2023 was determined by a series of field surveys. With the number of floors at the two dates, we compute the transition matrix T. The relevance of the transition matrix lies in that it can be used to predict the number of floors in different years and assess the change in the seismic vulnerability of masonry buildings.