How is Electrical Resistivity Imaging Used For Archaeology?

A person holding a skull


We don’t discuss archaeology nearly enough as it deserves. And since it’s October and Halloween is around the corner—why not talk about the spookier side of geoscience? Okay, archaeology isn’t actually scary—unless you’re claustrophobic (the fear of being in tight spaces) or have cartilogenophobia (the fear of bones), or have mummyphobia (which is what we guess the fear of mummies is called).  

But the real reason we want to discuss archaeology is that this year has seen several fantastic discoveries. This past Summer in our home state of Texas, a drought revealed some amazingly detailed dinosaur tracks. And while these tracks aren’t new findings, some remarkable discoveries are happening across the globe.


dinosaur fossil prints in lake

Via Smithsonian Magazine - Original Credit: Paul Baker / Friends of Dinosaur Valley State Park via Facebook


The Intricate and Delicate World of Archaeology

Each archaeological project has its own unique set of challenges. However, there is one thing all projects have in common. Every survey and every excavation requires a delicate touch; otherwise, there is a risk of potential loss or damage to invaluable historical artifacts and structures.

One of the many tools archeologists use is Electrical Resistivity Imaging (ERI). ERI is a geophysical survey method that involves sending electrical currents into the ground and measuring the resulting voltages to infer the resistivity of the subsurface materials. The images the data provides can reveal buried structures, artifacts, and other archaeological features without disruptive digging or excavation. As a result, archaeologists can make informed decisions about where to excavate—if at all—minimizing potential damage to precious historical remnants.


A photo of people using Electrical Resistivity Equipment and text that reads as: "Let's talk about what you need for your next project"


The Power of ERI in Archaeological Exploration

This method allows archaeologists to visualize subsurface structures and anomalies, providing a clearer picture of what lies beneath. Some use case examples are:

  • Guiding Excavations: Before starting an excavation, archaeologists can use ERI to target specific areas of interest, ensuring their efforts focus on the most promising locations.
  • Detection of Buried Structures: ERI can detect walls, foundations, pathways, and other buried structures by identifying differences in resistivity values between the archaeological features and the surrounding soil. This case history from a site in Kültepe is a great example.
  • Identification of Burial Sites: ERI can help locate graves or burial mounds by detecting subsurface anomalies corresponding to human-made pits or disturbances.
  • Locating Metal Artifacts: While ERI primarily detects resistivity contrasts in the soil, it can also indicate the presence of metal artifacts if they significantly affect the local resistivity.
  • Validation of Historical Records: ERI findings can be cross-referenced with historical texts or records to validate or challenge traditional narratives about a site.
  • Public Engagement: ERI data visualizations can be used in museums, visitor centers, and educational programs to help tell the story of the archaeological site.


An Example Fit for a King

A compelling example of ERI's capabilities in archaeology is this case history from Poland. ERI was employed to identify remnants at an ancient castle location. The resistivity data gathered clearly depicted the subsurface, revealing the outlines of former structures, fortifications, and other archaeological features.


A castle archeology site 


This method enriched the understanding of the castle's historical significance and layout of the site—while preserving the integrity of the castle's remnants.


Complementary Geophysical Methods

While ERI offers a wealth of information, it's often used with other geophysical survey techniques to view archaeological sites comprehensively. Ground Penetrating Radar (GPR) can complement ERI data, especially in diverse soil conditions. Meanwhile, magnetometry is particularly effective in detecting metal artifacts, offering another layer of data to archaeological investigations.


People digging at an archeology site

Via Trnava University on UnSpalsh - ERI can inform what excavation style to use


In Conclusion

Integrating ERI into archaeological practices can make a significant improvement to projects. ERI ensures that past stories continue accurately and respectfully by offering a non-invasive means to explore and understand historical sites. Coupled with other methods, ERI can provide thorough conclusions about dig sites.   

If you have any questions about ERI for archeological or other projects—reach out to our team to discuss what equipment you’ll need to complete the job! You can also follow us on LinkedIn and Facebook.


A photo of people using Electrical Resistivity Equipment and text that reads as: "Let's talk about what you need for your next project"