The Use DInSAR Technique for the Study of Land Subsidence Associated with Illegal Mining Activities in Zaruma – Ecuador, a Cultural Heritage Cite

Zaruma, a well-known mining district in the province of El Oro in Ecuador, suffers from subsidence phenomena related to illegal underground mining. Mining in this area goes back to the pre-Hispanic time; recorded history shows the first settlements of the Cañari culture and thru the Inca culture, and passing from the Spanish, American, and Canadian presence in the area up to modern times. Mining in this district has been in a constant transition from legal to illegal mining, technical and non-technical mining, prevailing activities in the present are illegal and non-technical over what is declared as the non-exploitation area under the city of Zaruma. This brings a series of problems among this land subsidence affecting the city cited as a cultural heritage cite; subsidence and collapses have accrued sporadically in the past, but in recent years (since 2017) this phenomenon has become a relatively consistent manner. In fact, December 15th, 2021, is the most recent sinkhole event resulting in the evacuation of over 300 people and the banning of over ten city blocks. For this reason, it is essential to find a quick and economical technique that can generate information about the spatial and temporal development of uncontrolled underground activities to improve risk management. In this work, the Differential Interferometry Synthetic Aperture Radar (DInSAR) technique, implemented in the SUBSIDENCE software, has been used to study terrain deformation related to illegal artisanal mining in Ecuador [1]. This work presents an up-to-date study of the monitoring and detection of subsidence phenomena in the city of Zaruma, as part of a collaboration project between local and international Universities allowing to detection and monitor surface deformations using DInSAR techniques as a tool applied to monitoring mining-related subsidence phenomena.