This code and data reproduce the results of the article "Citizens' smartphones unravel earthquake shaking in urban areas" by Francesco Finazzi, Fabrice Cotton and Remy Bossu. Part of the code is based on the D-STEM v2 software (Wang et al., 2021). The *.m files are MATLAB scripts to be executed individually: smartphone_station_bias_analysis.m: the script quantifies the bias between station and smartphone peak acceleration measurements (see Figure 3). highres_amplification_map.m: the script generates the site amplification maps of Figure 5. site_amplification_exposure.m: the script computes the site amplification exposure for the population, smartphone users of the Earthquake Network citizen science initiative, and buildings in the red zone of Campi Flegrei. highres_PGA_ShakeMap.m: the script generates the peak ground acceleration ShakeMap of Figure 6. GMM_comparison.m: the script calibrates the ground motion models whose parameters are given in Table 1. GMM_ShakeMap_prediction.m: the script generates the ShakeMaps in Figure 7 and in Supplementary Figures 6 and 7. References Wang, Y., Finazzi, F. & Fassò, A. D-STEM v2: A Software for Modeling Functional Spatio-Temporal Data. J. Stat. Softw. 99, 1–29 (2021).