The Influence of Fault Rupture Velocity on Ground Motions and Building Demands in the Near‐Fault Region

With the recent increases in measured ground motion records for large earthquakes, most notably the 2023 M7.8 Pazarcik earthquake in Türkiye, the potential for pervasive high velocity fault rupture propagation over an extensive fault length has been observed. This shallow strike‐slip event, with unprecedented near‐fault strong motion instrumentation throughout a large segment of the fault rupture zone, exhibited intense fault‐normal directivity pulses and fault‐parallel fling step for over two hundred kilometers along the fault. Observations of near‐shear (fault rupture velocity approaching the shear wave velocity) and supershear (fault rupture velocity exceeding the shear wave velocity) ruptures in recent major earthquakes, and the associated potential for highly damaging ground motions, motivate the need for deeper understanding of the relationship between high velocity ruptures and seismic risk to infrastructure systems. In this article, recent developments in high performance, regional‐scale fault‐to‐structure simulations are applied to provide additional insight into how high velocity ruptures can impact ground motions and the demands on building structures. First, the characteristic nonlinear response of buildings to observed intense near‐fault motions from the Türkiye event are assessed, and second, fault‐to‐structure simulations are performed for M7 strike‐slip events on the Hayward fault in the San Francisco Bay region for varying fault rupture velocities. These simulations illustrate the pronounced influence of fault rupture velocity and quantify the significant increase in regional seismic demand on structures for near‐shear and supershear scenarios.