Earthquake perception data highlight natural frequency details of Italian buildings

As the distance from an earthquake increases, percentage of people who do not feel it also increases. The average transition between “felt” and “not felt” reports is mainly determined by magnitude depth earthquake, but depends on observation floor building height. Buildings act as resonators can amplify shaking at specific frequencies. We analyzed over 286,000 crowdsourced to study effect height perception. found that, compared values, there increase in highest floors a decrease lowest buildings all heights. range within which observer likely (perception boundary) examined how varies with magnitude. that higher perceive medium high earthquakes progressively better than lower ones. perception boundary model seismic response spectra estimate vibration frequency perceived observers each floor/building combination. Our results show value fundamental period increases for top floor, modes become more evident 6 stories. In addition, we observed affects basement, tending Concerning macroseismic intensity estimation, tall buildings, observations made both upper must be considered outside normal range, changes function distance, pointing out importance collecting adequate number sample different locations observers.