Exploring a Maya Pyramid Ruin using Seismic and Radar Tomography
Matthew David Allen
A number of seismic surveys, in addition to a ground penetrating radar (GPR) test, have been conducted on a Maya pyramid ruin at the Maax Na archaeological site in Belize, Central America. The purpose of these surveys was to determine whether seismic and GPR tomography techniques could be used to create images of the pyramid's carbonate rubble interior and locate regions of archaeological interest. The hammer seismic signal transmitted through the entire 15 m high pyramid. Transmitted wave first breaks (time and amplitude) were picked for all the surveys and used in various inversions to create velocity and attenuation maps of the interior
The majority of interior seismic velocities fall within the range of 200 to 1000 m/s for all the different surveys. This velocity range falls into the expected values found using ultrasonic measurements of rock samples from the pyramid. The derived attenuation values for the interior of the pyramid also fell within a common range for all the different surveys. The majority of attenuation values fell between 0.1 and 5 Np/m. The derived models produced similar results in expected velocity and attenuation ranges thereby, providing confidence in the model. The derived models displayed interesting anomaly areas inside the pyramid. These areas may be associated with regions of archaeological significance.
A GPR test was performed on the pyramid to determine the viability of GPR in performing tomography on large structures. The GPR signal failed to penetrate through the entire pyramid. However, with the first breaks that were available a model was derived with reasonable velocities (0.08 to 0.12 m/ns).