Peru mudslide
It's summer in Peru and the mudslides are back, eroding barren hillsides on the western slopes of the Andes. The huaicos, as they are known in Peru, create rivers of mud and carry giant boulders with them that knock down everything in their path, from houses to bridges.

On Sunday, on the eastern fringe of Lima, Peru's capital, three mudslides tore through the towns of Chosica and Chaclacayo. A 15-year-old teenager, Johani Lucero Vasquez, dared to wade across a slide and was swept away. Her body was found 9 kilometers downstream. Debris washed onto the country's main highway that crosses the Andes, shutting it for six hours in both directions.

For most of the year, almost no precipitation falls on the barren landscape of steep, wrinkled canyons in the rain shadow of the Andes. But in the summer rains arrive and, because there is too little vegetation to absorb them, the hills come tumbling down.

People have been living in areas prone to huaicos, from the Quechua wayq'u, for thousands of years and towns in the Andes have escape routes showing where to run for higher ground in case they hit.

But there are signs the dangers are getting worse. The U.N. Climate Panel said in a 2007 report about the impacts of global warming that "many cities of Latin America, which are already vulnerable to landslides and mudflows, are very likely to suffer the exacerbation of extreme events".

And shantytowns grow on the eastern edges of Lima, where the cheapest land sits in narrow canyons smack dab in the path of the huaicos.