Regional Seismic Source Characterization for PSHA Across the Central and Eastern U.S.

Lettis Consultants International (LCI) played a key role in the Central and Eastern U.S. Seismic Source Characterization (CEUS-SSC) project—an advanced regional model developed to support Probabilistic Seismic Hazard Analysis (PSHA) for nuclear facilities. Sponsored by EPRI, DOE, and the NRC, the CEUS-SSC provides a technically robust and consistent foundation for evaluating seismic hazard across a broad geographic region.

Conducted as a SSHAC Level 3 study, the project established a structured and transparent process to capture the full range of scientifically credible interpretations. LCI staff were deeply involved in both the technical leadership and support:

  • Dr. Ross Hartleb, Dr. William Lettis, Mr. Scott Lindvall, Dr. Robin McGuire, and Dr. Gabriel Toro served on the 11-member Technical Integrator (TI) Team, guiding development of the seismic source characterization.
  • Dr. Randy Cumbest, and Dr. Frank Syms provided technical support for geophysics and geologic interpretations.
  • Mr. Serkan Bozkurt provided critical GIS, remote sensing, and database management support throughout the project.

A trusted tool for hazard assessments, the CEUS-SSC model is widely used for site-specific PSHAs, including Early Site Permit (ESP) and Construction and Operating License (COL) applications, as well as DOE and research facilities. Since its release, LCI has applied the model in numerous site-specific SSHAC Level 2 studies to refine source characterizations based on local data, perform sensitivity and uncertainty assessments, and support regulatory submissions.


Supporting Safety, Science, and Efficiency
The CEUS-SSC delivers broad value by enabling:

  • Consistent and repeatable inputs for seismic hazard analyses
  • Stable regulatory engagement through broad technical community involvement
  • Efficient licensing and design processes for nuclear infrastructure
  • Scientific advancement through new data, methods, and models

With decades of SSHAC experience and deep involvement in CEUS-SSC, LCI remains a trusted partner in advancing seismic safety and nuclear resilience across the U.S.