A scalable, 3D geophysical modeling and inversion code that uses geophysical measurements to generate images that serve as indicators of subsurface contaminant distributions, injection delivery extent, and dynamic biogeochemical processes. E4D was developed using the PNNL Nuclear Quality Assurance Program (NQAP), an American Society of Mechanical Engineers (ASME) NQA-1 quality program.

Computer graphic of E4D, showing the colorful three-dimensional image of what's underground.

E4D uses electrical resistivity tomography (ERT) measurements to reconstruct time-lapse images of the electrical conductivity of the soil. 

E4D is a 3D geophysical modeling and inversion program designed for subsurface imaging and monitoring. This award-winning R&D 100 E4D software provides customization for a wide range of field and laboratory applications, using:

  • Static and time-lapse electrical resistivity tomography (ERT)
  • Spectral induced polarization (SIP)
  • Travel-time tomography
E4D-RT: Real-time Four-Dimensional Subsurface Imaging 2016 R&D 100 Award Winner

High-Performance Computing Capabilities

E4D leverages distributed-memory high-performance computing, providing solutions for analyzing large geophysical datasets with high computational demands. E4D is highly scalable, and can be used on systems ranging from laptop computers to state-of-the-art supercomputing systems. The largest inversion executed to date involved a data set with approximately 5000 electrodes, 220,000 measurements, and a mesh with approximately 3 million elements, executed on NERSC supercomputing resources using 10,000 processors.

A scientific graphic with three images in yellow and red showing how fluids spread underground.
Electrical resistivity tomography (ERT) images provide near real-time distribution of injected fluid during subsurface hydrofracture flow testing. Surveys were conducted using four lines of 16 buried electrodes with autonomous data collected at 12-minute intervals.​​​​​ E4D inversion was executed on a remote supercomputer, returning images for field inspection every 15 minutes.


U.S. Department of Energy

  • Office of Environmental Management: Headquarters, Richland Operations, Office of River Protection
  • Office of Science: Subsurface Biogeochemical Research Program

U.S. Department of Defense

  • Environmental Security and Technology Certification Program

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