Chapter 4 Abstract. The landslide hazards analysis was the principal motiva- tion to start geomorphological investigations in the area of Machu Picchu Sanctuary. But very soon, the need of a broader research was revealed, because the landscape evolution of the Urubamba River meander, where the archaeological site is located, is rather com- plex. Besides slope movements, also deepwards erosion, and selec- tive mass wasting by weathering, suffusion etc. has been active. Majority of them have been following predisposition by tectonical structure. The existence of the large-scale deformations has seri- ously affected mountain morphology in the area. The actual activ- ity of those deformations is not well known yet, inspite that system- atic monitoring has provided information as about irreversible movements on open cracks of rock outcrops within the archaeo- logical site up to 1 mm yr –1 (lengths of time series is mostly 3 years), as about movement across the Main Plaza up to 6 mm yr –1 . The rea- son is, there still are other possibilities to explain those movements by ground deformation due to underground erosion along tectoni- cally shattered zones, or by settlements of heavy stone buildings on water more saturated grounds. In any case, even under present state of knowledge, the occur- rence of a large-scale catastrophically rapid slope collapse is im- probable within the short time interval of months or several years, if present-day conditions are maintained (in the absence of a strong earthquake). The question of present day activity of large scale land- slide bodies could be solved only by as multilateral research with using of all useful overlapping of geomorphology with hydrogeology, geophysics structural geology and engineering geology. Keywords. Landslides, monitoring, geomorphology, Machu Picchu, Peru 4.1 Introduction Geomorphology, in comparison with geological studies, had been at the periphery of scientific interests in the Machu Picchu Sanctuary for a long time since its discov- ery in 1911. However, in papers by Carreño et al. (1996) and Carreño and Bonnard (1997) questions had been arisen as to the safety of the archaeological World Heritage Monu- ment in case of catastrophic landslide events. Therefore, after preliminary investigations of Sassa et al. (2000); Sassa (2001); Vilímek and Zvelebil (2002), the site has been pro- moted into UNESCO/IGS, IGSP 425 and then into ICL/IPL Projects of complex assessment of landslide risk. Geomorphological research in this area was carried out within regionally oriented geological investigations (e.g. Ponce 1999; Carlotto et al. 1999). In these studies, geomorphology was presented mostly in a descriptive way without synthesis and deduction about landscape evolu- tion. On a local level there exists one study directly de- voted to the geomorphology of the archaeological site written by Manrique et al. (1998). An important task in the landslide risk assessment is to estimate the actual rates of displacements deformations in landslide susceptible areas. A monitoring network was recommended already by Carreño and Bonnard (1997), but the first steps to its realization were taken by Sassa et al. (2000). Twelve sites were instrumented by wire ex- tensometers. Two of them were equipped by automatic registration. The results of those monitoring measure- ments (Sassa 2001; Sassa et al. 2001) suggested existence of a permanent displacement of the order of mm per month or greater. Our geomorphological investigations in this area started in 2001, when a preliminary field survey was done and a new basic strategy for monitoring network of sites Geomorphological Investigations at Machu Picchu, Peru (C101-1) Vít Vilímek* · Jiàí Zvelebil · Jan Klimeš · Ján Vláko · Fernándo V. Astete Fig. 4.1. Photo of Machu Picchu archaeological site with localization of dilatometric measurements. C: Cave (measuring site C1); T: Principal Temple (T1, T2, T3); I: Intiwatana (I1, I2, I3); P: Plaza (P1); W: Huayna Picchu (W1, W2, W3); A: Acllawasi (A1); M: Wairana o Mirador (M1, M2, M3, M4); R: Rodadero (R1, R2, R3); Q: Qhata (Q1). Qualitative evaluation of trends of movements. Red color: irre- versible movements; green color: without any irreversible movements; light blue: cannot be still interpreted