Ambient vibration analysis of high-rise buildings using MyShake smartphone data

This study investigates the feasibility of using smartphones equipped with the MyShake application to measure the natural frequency and damping ratio of buildings from ambient vibrations. Originally developed as a citizen science tool, MyShake became widely adopted for delivering earthquake early warning (EEW) messages. It also autonomously records three-component acceleration data in 5-min segments to conserve battery. We developed an automated technique optimized for these recordings, using multi-taper spectral analysis and the half-power bandwidth method to extract dynamic building properties. To assess the influence of sensor noise, we simulated smartphone recordings by adding MyShake-equivalent noise to high-quality sensor data and confirmed that key frequency peaks remained detectable. Field deployments across four buildings in the San Francisco Bay Area—ranging from mid-rise to tall structures—demonstrated that taller buildings consistently produced reliable measurements, even under low-wind conditions. In contrast, shorter buildings required stronger ambient excitations to yield accurate frequency estimates. Results from smartphone data closely aligned with those from previous studies using the traditional seismic sensors, validating the method's accuracy. By integrating ubiquitous smartphone sensing with operational modal analysis, this work presents a scalable, low-cost approach for continuous structural health monitoring, with strong potential for early detection of changes in high-rise buildings. © 2025