Seismic safety in hydropower infrastructure is not a handoff between disciplines – it’s a continuum of understanding that begins with the fault and ends with the foundation and structure. When separate teams perform seismic hazard, deformation, and structural analyses, subtle differences in assumptions can compound into inconsistent results. True resilience emerges when these disciplines operate as a single, integrated analytical chain.
At GFT, seismic hazard, deformation, and structural analyses are performed within one integrated team.
“Integration is what allows our work to move beyond compliance,” said GFT’s Vice President and Chief Seismic Hazard Engineer Dina Hunt, PE. “When the same team carries the analysis from ground motion through structure, every assumption is transparent, and that’s what builds trust with dam owners, regulators, and everyone who depends on the reliability of our work.”
Defining the hazard: where resilience begins
Every dam’s seismic analysis story begins with understanding the ground it stands on. Comprehensive seismic hazard analysis integrates deterministic and probabilistic approaches to characterise the full range of potential ground motions.
“At its core, seismic hazard analysis is storytelling,” said Chief Seismic Hazard Engineer Melanie Walling, PhD, PE. “We’re defining how the earth beneath a dam could behave over its lifetime, and that narrative shapes every decision that follows.”
For a major hydroelectric facility in the Pacific Northwest, the team updated the seismic hazard framework and developed site-specific time histories, working closely with Federal Energy Regulatory Commission (FERC) regulators. The same specialists who defined the ground motions also participated in deformation discussions, ensuring that every assumption remained transparent and traceable.
“That continuity eliminates the ‘translation gap’ between teams,” added Senior Geotechnical Analyst Kwestan Salimi, PhD, PE. “It’s one story told consistently from beginning to end.”
“From a geological perspective, every seismic model is only as good as the foundation it’s built on,” said Principal Engineering Geologist Michael Gray, PG, CEG. “Our role is to ensure that the fault mapping, site characterisation, and subsurface data model what’s happening in the ground, because that’s where seismic resilience starts.”
From hazard to behaviour: modelling dam response
If hazard analysis tells us how the ground moves, deformation analysis tells us how the dam will respond to those movements. At an embankment dam in Hawaii, nonlinear deformation modelling helped evaluate performance under a major seismic event.
“Our geotechnical and hazard teams sat side by side through every iteration,” said Principal Civil Engineer Justin Buetel, PE. “That collaboration assured that the deformation models reflected the seismic inputs and appropriately estimated the real-world behaviour of the dam under a hypothetical seismic load.”
This approach eliminated the “telephone game” effect that often occurs when analyses are divided among firms. The benefit of this integration extends beyond technical consistency. When the same team defines both the seismic demand and the structural response, questions from regulators or review boards can be answered efficiently, with a clear understanding of how each assumption influenced the results.
Closing the loop: structural performance assessment
Integration reaches its fullest expression when hazard, deformation, and structural expertise converge. At a concrete arch dam in Colorado, the structural team re-evaluated stress, stability, and dynamic behavior under combined seismic and thermal loading.
“For me, the most valuable part of this process is the feedback loop,” explained Senior Structural Engineer Aimee Corn, PE. “When I can trace every load case back to its seismic source, I know our model isn’t just numerically sound; it’s physically meaningful.”
This alignment of hazard inputs, nonlinear modelling, and structural assessment created a cohesive understanding of dam behaviour and built confidence among regulators and dam owners alike.
Collaboration as technical practice
Behind every integrated analysis lies a network of expertise that functions as a single organism. Seismic hazard specialists provide ground motion inputs that align with the deformation modelling team’s needs, with time histories and target spectra developed to reflect the site’s seismic environment and structural characteristics. Structural analysts use those same results to refine finite element models. Oversight validates the assumption and results remain consistent across all phases.
“We think of collaboration not as a project phase but as a technical discipline,” said Walling. “It’s the structure that holds our analyses together.”
Each model, from hazard curves to finite element simulations, is developed with the next analytical step in mind and reviewed across disciplines before delivery. The process isn’t a series of handoffs, but a continuous conversation that continues until the system is fully understood.
An evolving industry perspective on seismic analysis
The hydropower industry’s approach to seismic safety has evolved significantly. Where evaluations were once viewed primarily as regulatory exercises, they are now recognised as essential tools for understanding resilience. This shift has been driven by updated seismic hazard models, aging infrastructure that requires reassessment, and a growing recognition that downstream consequences have increased as development expands.
The industry has also moved toward viewing seismic safety as a continuous process. Owners now regularly revisit and refine their understanding of risk, integrating new inspection results, analytical updates, and lessons from events elsewhere. This adaptive approach creates infrastructure that responds to evolving conditions rather than remaining locked into outdated assumptions.
“Owners are realising that seismic analysis isn’t a one-time event – it’s a living process,” said Hunt. “Every update, every new dataset, makes the system safer and smarter.”
Key considerations for integrated seismic evaluation
For hydropower projects, successful seismic evaluation depends on several critical factors. Site-specific hazard analyses incorporating local fault geometry and site response characteristics provide more reliable estimates than regional maps. Accurate characterisation of foundation and embankment materials, including their strength-strain properties, ensures that models accurately reflect their actual behavior.
Equally important is maintaining analytical continuity. When the same team develops ground motion inputs, performs deformation modelling, and evaluates structural response, the consistency of assumptions across all phases reduces uncertainty and accelerates regulatory review. Finally, integrating technical analysis with routine inspections and operational monitoring creates feedback loops that strengthen resilience over time.
Resilience through integration
True resilience emerges when integrated teams ensure that critical infrastructure, and the communities it serves, remain safe and reliable. When geologists, geotechnical engineers, and structural specialists collaborate from hazard definition through performance assessment, the result is more than technical precision. It is confidence that infrastructure has been evaluated thoughtfully, that assumptions have been challenged across disciplines, and that dam owners and communities can trust the conclusions.
“When the same team defines the fault, models the deformation, and evaluates the structure, we reduce uncertainty,” said Salimi. “That’s how we deliver confidence, not just compliance.”
As communities continue to emphasise resilience over simple compliance, integrated practice becomes not only advantageous but essential. The path forward requires bringing together the full spectrum of seismic expertise, from fault characterisation to foundation response, under a shared analytical framework that serves both rigour and clarity.
Author details
Melanie Walling, PhD, PE, Chief Seismic Hazard Engineer, mwalling@gftinc.com
Dina Hunt, PE, Vice President & Chief Seismic Hazard Engineer, dbhunt@gftinc.com
Aimee Corn, PE, Senior Structural Engineer, acorn@gftinc.com
Justin Buetel, PE, Principal Civil Engineer, jbeutel@gftinc.com
Kwestan Salimi, PhD, PE, Senior Geotechnical Analyst, ksalimi@gftinc.com
Michael Gray, PG, CEG, Principal Engineering Geologist, mgray@gftinc.com
