'Illuminating' the interior of Kukulkan's Pyramid, Chichén Itzá, Mexico, by means of a non-conventional ERT geophysical survey

Chichén Itzá, located in the north-central portion of the Yucatán Peninsula, is one of the major pre-Hispanic cities established in the southern lowlands of Mexico. The main objective of this investigation was to “unveil” the interior of the pyramid of El Castillo, also known as the Temple of Kukulkan, an emblematic structure in this archaeological site. To that end, 828 flat electrodes were deployed around each of the 9 bodies that compose the pyramid, including the base of the structure. A dataset consisting of 37,548 observations was obtained. A precise topographic control for each electrode was carried out and introduced in the inversion model. The mathematical process to compute a final 3D model was made possible by taking 9 observation levels (33,169 measurements) into account, due to computational limitations. The results showed the existence of two older pyramids within the main Mayan building and provided important information regarding our understanding of this Mayan civilization. Future archaeological studies in the older substructure could reveal information about early settlement on this site, its evolution in time and its cultural influences.