Underground mining can produce subsidence phenomena, especially if orebodies are surficial or occur in soft rocks. In some countries, illegal mining is a big problem for environmental, social and economic reasons. However, when unauthorized excavation is conducted underground, it is even more dangerous because it can produce unexpected surficial collapses in areas not adequately monitored. For this reason, it is important to find quick and economic techniques able to give information about the spatial and temporal development of uncontrolled underground activities in order to improve the risk management. In this work, the differential interferometric synthetic aperture radar (DInSAR) technique, implemented in the SUBSOFT software, has been used to study terrain deformation related to illegal artisanal mining in Ecuador. The study area is located in Zaruma (southeast of El Oro province), a remarkable site for Ecuadorian cultural heritage where, at the beginning of the 2017, a local school collapsed, due to sinkhole phenomena that occurred around the historical center. The school, named “Inmaculada Fe y Alegria”, was located in an area where mining activity was forbidden. For this study, the surface deformations that occurred in the Zaruma area from 2015 to 2019 were detected by using the Sentinel-1 data derived from the Europe Space Agency of the Copernicus Program. Deformations of the order of five centimeters were revealed both in correspondence of known exploitation tunnels, but also in areas where the presence of tunnels had not been verified. In conclusion, this study allowed to detect land surface movements related to underground mining activity, confirming that the DInSAR technique can be applied for monitoring mining-related subsidence.

In this study, we present evidence for the use of slingstones and other projectile stones among the ancient Maya peoples of the Usumacinta River region. Rounded stones are frequently found across Maya archaeological sites and are given a range of interpretations, including objects for flintknapping, cooking, ritual, divination, and less often as weapons. Here we provide new evidence for the identification of rounded stones as weapons based on their morphology as well as their context of recovery. We employ data from the sites of Macabilero, Guatemala, and Budsilha, Mexico, which strongly suggest rounded stones at these sites were manufactured to be used as weapons. These findings have implications for how we understand warfare and hunting in ancient Mesoamerica and inform our interpretation of how the Maya prepared for such activities. As a class of weapon potentially accessible to most members of Maya society, the results presented here show the importance of more inclusive perspectives on Maya warfare and the necessity of contextualizing artifact analysis within the occupation history of the broader site and region.

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