Geophysics & Seismology

Geophysics and Seismology

RIZZO conducts various geophysical tests at project sites in support of site response analysis, including surface surveys and downhole loggings.

RIZZO performs high-resolution seismic surveys to evaluate shallow subsurface geology, as well as to delineate and verify possible Quaternary faulting.

RIZZO also performs full scale seismic hazard studies for conventional and critical engineering structures, and derives the design ground motions for these structures.

We also perform the following services in support of computing seismic hazard and design ground motions:

  • Seismotectonic studies
  • Seismicity studies and statistical analysis of earthquake catalogs
  • Seismic source characterization and estimation of associated seismicity parameters
  • Evaluation and adjustment of ground motion prediction equations for different target sites
  • Probabilistic Seismic Hazard Analysis (PSHA) and derivation of rock uniform hazard response spectra
  • Seismic site response analysis
  • Derivation of design ground motions

Our professionals utilize the firm’s in-house software, RIZZO-HAZARD, for seismic hazard analysis computations.

The software can perform the following computational tasks:

  • Statistical analysis of earthquake catalogs
  • Estimation of seismicity parameters
  • Computation of seismic hazard
  • Deaggregation of the hazard
  • Identification of the controlling earthquakes
  • Derivation of design ground motions

This software is based on object-oriented architecture that allows for easy maintenance and expansion. Different objects can be added without important impact on the overall program. For example, new recurrence relationships, smoothing schemes for the recurrence rates along the source zones, Ground Motion Prediction Equations, magnitude conversion schemes, and controlling earthquake spectral shapes can be easily implemented in the program.

RIZZO-HAZARD also provides a user friendly visual interface to assist the analyst in creating the computational model and interpreting the results.

Work performed for site response analyses is carried out using RIZZO’s in-house version of SHAKE; additionally, the in-house software “HIST” and in-house version of RSPM are used for matching time histories used in the site response analysis.