The First Electrical Resistivity Tomography Study Applied to an Ecuadorian Cave (Uctu Iji Changa, Tena): Insights into Amazonian Karst Systems

The presence of carbonate rocks and high levels of precipitation have led to the ubiquitous formation of karstic caves in the Napo region of Amazon in eastern Ecuador. Caves such as these represent an important scientific target as they are typically well-suited for paleontological, geophysical, geochemical, and paleoclimate studies. Previous works have shown that resistivity surveys are a very efficient and appropriate way to detect and define shallow caves. However, no studies of this type have been conducted on Ecuadorian caves. Here, we present the first study of this kind from Ecuador. We show the results of applying the electrical resistivity tomography (ERT) technique to characterize the cave Uctu Iji Changa in Napo, Tena, Ecuador. The ERT study was corroborated by speleological inspection of the cave to verify the results from the geophysical surveys. ERT allowed us to determine the location, general geometry, and extent of the cave. In all survey lines, the resistivity contrast between the air- filled voids of the cave and the bedrock is high enough to define the shape and size of the cavity. To Know the geomorphology of the cave will allow a better land-use planning to prevent karst resources from being exhausted in developing regions. The research promotes public awareness of the importance of karsts and the threats facing them. Our results demonstrate the efficacy of the ERT technique for detection of shallow caves associated with karstic processes