The city's lone water-and-sewer utility can barely provide water to one-tenth of Lima in the best of times.Another big concern: Lima has no emergency operations center and the radio networks of the police, firefighters and the Health Ministry, which runs city hospitals, use different frequencies, hindering effective communication. Nearly half of the city's schools require a detailed evaluation to determine how to reinforce them against collapse, Sato said. A recent media blitz, along with three nationwide quake-tsunami drills this year, helped raise consciousness. The city has spent more than $77 million for retention walls and concrete stairs to aid evacuation in hillside neighborhoods, Prado said, but much more is needed. At the biggest risk, apart from tsunami-vulnerable Callao, are places like Nueva Rinconada. A treeless moonscape in the southern hills, it is a haven for economic refugees who arrive daily from Peru's countryside and cobble together precarious homes on lots they scored into steep hillsides with pickaxes. Engineers who have surveyed Nueva Rinconada call its upper reaches a death trap. Most residents understand this but say they have nowhere else to go. Water arrives in tanker trucks at $1 per 200 liters (52 gallons) but is unsafe to drink unless boiled. There is no sanitation; people dig their own latrines. There are no streetlamps, and visibility is erased at night as Lima's bone-chilling fog settles into the hills. Homes of wood, adobe and straw matting rest on piled-rock foundations that engineers say will crumble and rain down on people below in a major quake. A recently built concrete retaining wall at the valley's head lies a block beneath the thin-walled wood home of Hilarion Lopez, a 55-year-old janitor and community leader. It might keep his house from sliding downhill, but boulders resting on uphill slopes could shake loose and crush him and his neighbors.