The Long and the Short of It: Duration in Earthquake Hazard Analysis

Natasha Tiwari, Mario Chong Loo, Yongfei Wang, & Scott Callaghan

Submitted September 7, 2025, SCEC Contribution #14631, 2025 SCEC Annual Meeting Poster #TBD

Traditional seismic hazard models emphasize amplitude-based metrics such as peak ground acceleration or response spectral acceleration, but often neglect an equally critical factor: ground motion duration. Duration strongly influences structural damage potential, collapse risk, and recovery time; particularly for long-period structures and soft-soil sites. However, duration continues to remain underrepresented in hazard frameworks.

This project uses CyberShake, a physics-based ground motion simulation platform developed by the Southern California Earthquake Center, to analyze earthquake duration using the D5–95 metric (the time interval between 5% and 95% cumulative Arias Intensity). We retrieved and organized supporting site metadata, including basin depth (Z1.0, Z2.5) and rupture distance, from CyberShake’s database to enable future correlation studies. To contextualize results, we compared CyberShake synthetic data to empirical records from the NGA-West2 database.

Our results show clear duration trends with magnitude and rupture distance, and demonstrate CyberShake’s ability to produce denser and broader coverage than recorded datasets; capturing rare, high-magnitude events often missing from empirical archives.

By adding duration to hazard assessment, this work lays the foundation for next-generation seismic hazard models that integrate both intensity and time-domain effects, ultimately improving resilience planning and engineering applications. Future directions include expanding site coverage, developing predictive models, and exploring period-dependent duration metrics.

Citation
Tiwari, N., Chong Loo, M., Wang, Y., & Callaghan, S. (2025, 09). The Long and the Short of It: Duration in Earthquake Hazard Analysis. Poster Presentation at 2025 SCEC Annual Meeting.

Related Projects & Working Groups
Ground Motions (GM)