A 7.5-magnitude quake in 1974 a day's drive from Lima in the Cordillera Blanca range killed about 70,000 people as landslides buried villages. Seventy-eight people died in the capital. In 2007, a 7.9-magnitude quake struck even closer, killing 596 people in the south-central coastal city of Pisco.
A shallow, direct hit is the big danger.
More than two in five Lima residents live either in rickety structures on unstable, sandy soil and wetlands that amplify a quake's destructive power or in hillside settlements that sprang up over a generation as people fled conflict and poverty in Peru's interior. Thousands are built of colonial-era adobe.
Most quake-prone countries have rigorous building codes to resist seismic events. In Chile, if engineers and builders don't adhere to them they can face prison. Not so in Peru.
"People are building with adobe just as they did in the 17th century," said Carlos Zavala, director of Lima's Japanese-Peruvian Center for Seismic Investigation and Disaster Mitigation.
Environmental and human-made perils compound the danger.
Situated in a coastal desert, Lima gets its water from a single river, the Rimac, which a landslide could easily block. That risk is compounded by a containment pond full of toxic heavy metals from an old mine that could rupture and contaminate the Rimac, said Agustin Gonzalez, a PREDES official advising Lima's government.
Most of Lima's food supply arrives via a two-lane highway that parallels the river, another potential chokepoint.
Lima's airport and seaport, the key entry points for international aid, are also vulnerable. Both are in Callao, which seismologists expect to be scoured by a 20-foot (6-meter) tsunami if a big quake is centered offshore, the most likely scenario.
Mayor Susana Villaran's administration is Lima's first to organize a quake-response and disaster mitigation plan. A February 2011 law obliged Peru's municipalities to do so. Yet Lima's remains incipient.