## 2 Materials and Methods  
For this research, images acquired by the satellite constellation COSMO-SkyMed (also referred to as CSK), a dual-use (i.e., civilian/military) programme funded by ASI and the Italian Ministry of Defence [19; 20], were used. The constellation is made of four identical space-crafts (i.e., CSK1, CSK2, CSK3, and CKS4), each equipped with multimode SAR sensors operating in the X-band (9.6 GHz frequency; 3.1 cm wavelength) and with nominal revisit time of 16 days. The CSK satellites were progressively deployed from 2007 to 2010 into a dawn-dusk sun-synchronous low Earth orbit (619.6 km nominal altitude), with the constellation becoming fully operational in the first half of 2011 [21]. Figure 2: Overview of the locations investigated in this paper: (**a**) 2015 photograph of the section of the Pan-American Highway where the “plowing” event occurred on 27 January 2018 (source: Street View © 2018 Google); and 2013 aerial views acquired over: (**b**) the Observation Tower and its parking lot, with indication of the Hands and Tree geoglyphs; and (**c**) the plateau where the Hummingbird geoglyph is located and the surface disturbance event occurred on 8 December 2014 (photo credits: [PERSON]; source: Wikimedia Commons). The COSMO-SkyMed data used for this research were acquired in StripMap HIMAGE mode, hence with 40 km swath width, 0.9 m slant range, and 2.2 m azimuth pixel spacing (i.e., around 3 m ground resolution). The data stack was collected with a consistent imaging geometry, orbit mode, and beam. In particular, the ascending orbit direction with a heading angle of 12.2\({}^{\circ}\) off the north (N) direction and the right-looking mode was used. Acquisitions were performed with HH single-polarisation and using the H4-01 beam mode, with look angle ranging between \(\sim\)22.6\({}^{\circ}\) and \(\sim\)25.6\({}^{\circ}\) at near and far range, respectively, resulting in a \(\sim\)26.7\({}^{\circ}\) incidence angle on the ground at scene centre. The images were acquired at \(\sim\)11.10 am UTC (Coordinated Universal Time), i.e., \(\sim\)06.10 am local time at Nasca, with scene centre at 14\({}^{\circ}\)46\({}^{\circ}\)25\({}^{\circ}\)S, 75\({}^{\circ}\)13'08\"W and with an image size on the ground of 40 by 50 km (Figure 1). For this analysis, two events of site disturbance occurred within the Nasca Lines WHS at two different locations (black stars in Figure 1) on 8 December 2014, and 27 January 2018, were selected. These events, described in Sections 3.1 and 3.2, were chosen for demonstration, according to the following three criteria: (i) their geographic location could be accurately identified based on published official information and pictorial evidence from published photographs and videos; (ii) the type of site disturbance caused changes that could be tracked based on the alteration of SAR properties at the surface; and (iii) they were, of course, covered by the time series of COSMO-SkyMed scenes available over Nasca. To investigate these two events, a stack of seven scenes acquired between 10/07/2014 and 30/01/2018 was used (Table 1). Image processing started from Level 1A products, i.e., single-look complex slant range balanced (SCS_B) data. These were generated after the focusing of raw Level 0 products in slant range and zero Doppler projection, compensation of antenna transmitter gain, receiver attenuation and range spreading loss, as well as weighted processing and radiometric equalization [21].