Teotihuacan was a massive, important, city near modern day Mexico City. There are several massive pyramids on the site and two of them have caves UNDER the pyramid. The pyramid of the moon was the focus of the paper linked below and Denisse Argote and Andres Tejero use two techniques to try to identify the presence or absense of a cave beneath it. Those techniques are Electrical Resistivity Tomography (ERT) and Ambient Noise Tomography (ANT).
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Chris Webster
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Paul Zimmerman
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