Update of the Seismic Microzonation Map of Lima and Callao, Peru

Lima City and Callao Province are located in the Pacific Ring of Fire and have experienced major earthquakes over the years. To understand the seismic response of the soil, a seismic microzonation study was developed, taking into account the results of geological, geotechnical, and geophysical surveys. The geological study identified areas with potential for rockfall on the existing hills in Lima. The geotechnical exploration included survey drilling, soil sampling for analysis, and standard penetration test. The results defined the mechanical characteristics of the soils and identified their strength and behavior as foundation materials. The geophysical exploration consisted of single-point microtremor measurements, microtremor arrays, MASW (multichannel analysis of surface waves), and refraction tests. The results provided the natural period of vibration and the velocity profiles of the P and S waves, allowing the dynamic characteristics of the soils to be identified. The results of the geological, geotechnical, and geophysical surveys were superimposed to develop the geotechnical microzonation map, the isoperiod map, and the seismic microzonation map for Lima City and the Callao Province. The latter identifies five zones, where the area with the best mechanical and dynamic soil characteristics covers most of the study area.