## 2 Riotinto Mine Context  
The Iberian Pyrite Belt (IPB) is a large Variscan metallogenic province around 250 km long and 20-70 km wide along Portugal and Spain, hosting the largest concentration of massive sulfide deposits worldwide [21; 22]. The main mining interest is and has been precious metals (Au, Ag), base metals (Cu, Zn, Pb), and sulfuric acid. The major mineralization, as volcanogenic massive sulfides and related stockworks, was deposited in pull-apart intracontinental marine basins related to the closure of the Rheic Ocean due to the collision between the South Portuguese Zone, an allochthonous terrane, and the autochthonous Iberian terrane during the late Devonian-Visean [23; 24; 25]. The Riotinto mining district is the largest of the nine giant massive sulfide deposits of the Iberian Pyrite Belt (IPB) and one of the largest sulfur anomalies in the Earth's crust. The dimensions of the orebody and its intense (and sometimes turbulent) long history make it a mining emblem. Since 4000 BC, mining activity is documented by Tartessians, Phoenicians, Romans, Arabs, Spanish, British, and modern multinational companies [26]. Currently, the Atalaya Mining company owns the mine and focuses on copper production. The mine area covers \(\sim\)36 km\({}^{2}\) divided into two zones, the Atalaya abandoned open pit, and the Cerro Colorado active pit (Figure 1). The geology of the area is quite complex and includes a thick volcanic unit, the Volcanosedimentary Complex [27] with basaltic flows and sills intruding shale overlain by several superimposed hyroodacite domes. These rocks are covered, through an out-of-sequence large thrust, by a synorogenic flysch-like sequence, the Culm Group. These volcanic rocks have been affected by the aforementioned Variscan orogen causing widespread folding and thrusting structures, which were later reactivated during the Alpine orogen [27]. This deformation has produced a complex network of fractures that nowadays controls the hydrology and the geotechnical behavior of the mined rocks. Before 1907, the mining activity was underground, as a result, countless galleries crosscut the site. Then, after major collapses, underground works were replaced by several open pits, being most of them nowadays infilled. At its peak, the Atalaya open pit was the largest in Europe, being finally abandoned in 1994. The dimensions and elliptical shape (1200 m long, 900 m wide, and 350 m deep) make it a reference in open mining. However, the interplay of the previous structures has produced the widespread collapse of  
Figure 1: Main mining elements in Riotinto mine. The mining site is divided into one active zone to the east and one passive zone to the west. The small map shows the localization of the Riotinto’s mine (yellow square) and the Sentinel-1 footprints, ascending (red) and descending (blue), of the selected tracks to be used in Section 4. In this specific configuration, both incidence angles on Riotinto are close to 42\({}^{\circ}\). old underground works and the sliding of faces within the pit. Of special interest is the east side of the open pit where the conjunction of shale and a major fault weakens the wall, showing a continuous sliding process linked to the old mining activity. The concern caused by the deformation observed in this area is the main motivation behind this study, and it will be discussed in detail in Section 4. The Atalaya pit is surrounded by passive dumps, of around 3.5 km\({}^{2}\), which we will also analyze. Nearby, to the east, the Cerro Colorado pit is currently the active part of the license. It is a complex mine with 3 pit faces, resulting in an irregular shape, with a maximum length of 2020 m, a maximum width of 850 m, and a maximum depth of 230 m. In 1964 began the digging works, but due to the low profit, the activity stopped in 2001. As a consequence of the improvement of the metal market, Atalaya Mining resumed its mining activity in 2015, and it is now at full capacity. According to the estimated reserves, it can extend to 17 or 25 more years.