Surface ruptures caused by earthquakes can tear through the ground, damaging pipelines, roads, dams, and power plants. While engineering solutions can reduce some risks, experts say the best protection remains avoiding construction directly across active faults. A new article in Reviews of Geophysics revisits the evolution of Probabilistic Fault Displacement Hazard Assessments (PFDHAs), a scientific method that helps predict and quantify surface rupture hazards.
Fault displacement happens when an earthquake ruptures the Earth’s surface, shifting the ground horizontally or vertically by several meters. Such movements can severely damage critical infrastructure built across faults, making it essential to understand where and how these ruptures might occur.
PFDHAs estimate the likelihood that an earthquake will rupture the ground surface at a particular site and predict how much displacement might occur. Instead of a single outcome, these assessments calculate probabilities for different displacement levels over specific timeframes. This data-driven approach helps engineers and planners make informed decisions on building designs and land use in fault zones.
The first systematic PFDHA was developed in the early 2000s for the Yucca Mountain nuclear waste repository in the United States. Since then, the method has evolved globally to include various fault types normal, strike-slip, and reverse. Advances in statistical modeling, remote sensing, and international benchmarking have made assessments more accurate and comparable. Modern efforts are now focusing on incorporating artificial intelligence and physics-based modeling to better represent complex fault behaviors.
Beyond technical insights, the societal benefits of PFDHAs are significant. They guide safe infrastructure design, help identify zones where construction should be avoided, and ultimately reduce economic and human losses during earthquakes. Countries like Japan and Italy have already implemented PFDHAs for assessing risks to dams, tunnels, and other vital facilities.
Recent progress includes the creation of global databases such as the Surface Rupture Database (SURE) and the Fault Displacement Hazard Initiative (FDHI), which compile data from thousands of past surface ruptures. New satellite and drone-based remote sensing methods have improved the precision of rupture mapping. Importantly, scientists have discovered that even moderate earthquakes below magnitude 6.5 can cause significant ground rupture, challenging earlier assumptions.
Despite advances, several gaps remain. Many regions outside North America and Japan lack detailed rupture records, and modeling complex multi-fault events continues to be difficult. Understanding how surface geology influences rupture behavior is another key research need. Experts also stress the importance of standardizing global methods and terminology to ensure consistency in hazard assessments.
Future research aims to merge high-resolution data with physics-based simulations and expand monitoring networks. These improvements could transform how communities plan infrastructure, reduce the risk of catastrophic damage, and enhance resilience in earthquake-prone regions.