The entire ruins of Machu Picchu in Peru--designated a World Heritage site by UNESCO in 1983--are in danger of collapse due to landslides, according to the findings of a survey conducted by a team of researchers led by a Kyoto University professor.
Prof. Kyoji Sassa of the Disaster Prevention Research Institute at Kyoto University issued the warning during a lecture at the institute Friday. He said he had noticed traces of several small landslides in the past on both sides of the Inca ruins when he surveyed the topography and the citadel buildings from the air and on the ground in March 2000.
Sassa added he had found many recently distorted or collapsed parts of buildings lying from north to south at the center of the ruins.
In November, he placed 10 seismic devices in the ruins to measure ground expansion and contraction. The rate of expansion measured about one centimeter in one month, which according to Sassa is a precursor of a landslide.
The findings of the survey also revealed that the fortresslike city, located atop an Andean mountain 2,550 meters above sea level, was built on ground on the summit that itself had been flattened by landslides.
Sassa said he will continue to study the ruins, now Peru's most popular tourist site, in cooperation with UNESCO and Peru's National Institute of Culture to try and find ways to avert the collapse of the site.
Archeologists believe the Machu Picchu citadel was constructed during the 15th and 16th centuries by the Inca. Its stone shrines, houses and plazas cover a 3,300-hectare tract of land.
U.S. archeologist Hiram Bingham discovered the ruins in 1911. The site is known as "the city in the air," and rumored by some to be where the Inca empire hid its treasures because it is invisible from below.