COLORADO SPRINGS — A geologist knocked on Sherry Cripps’ door more than a decade ago and warned her that her home on Cheyenne Mountain was sitting atop a slow-moving, destructive landslide. He told her to abandon the home.

Cripps dismissed the aging geologist as crazy until 2015, when his predictions came true. She and her husband Denny are close to abandoning their nearly unlivable home, as it is cracking in half and sliding off a hill. The Cripps and their neighbors are confronting a behemoth that lay dormant for years: a landslide zone one and a half times the size of Manhattan.

Thousands of homes in the southwest corner of the city were built in the slide zone, despite repeated warnings from geologists who said the area was risky for development and recommended caution in approving construction.

City officials have known about the problem since at least the mid-1990s, when they passed an ordinance designed to restrict development, but the measure has not been enforced and new homes have gone up almost unabated.

In other parts of the state where similar problems have occurred — including Boulder and Jefferson counties — landuse code prohibits building on known landslide areas.

Insurance will not cover the losses. At least 70 homeowners in southwest Colorado Springs are seeking federal grants to help buy out their destroyed or imperiled houses — the third round of such funding for the city. Nineteen of those properties are located in neighborhoods surrounding a Broadmoor Hotel golf course where a landslide has been an issue for years.

“In my mind, the process threw caution to the wind,” said Jon White, a geologist with the Colorado Geological Survey. “Many knew the risks. Everybody should have been more cautious and the risks should have been disclosed to the potential homebuyers.”

The Cripps and other homeowners near Cheyenne Mountain say they were the last to learn of the danger their homes sit on. Knowledge of the risk would have changed everything, Sherry Cripps said. “We would have been going to the developer and saying, ‘Hey, buy this back.'”

In a letter to Colorado Springs officials last week, state geologists urged the city to take more aggressive action than they have to monitor and assess the risk the Broadmoor golf course slide poses to homes, infrastructure and residents of the area.

Typically, the state’s geologists serve in an advisory role, conducting studies of areas at risk of landslides and making nonbinding recommendations. But it is up to local governments that choose to work with them to decide whether and how development will occur.

A city spokeswoman acknowledged in an email that the city has known about the landslide risk near Cheyenne Mountain since 1996, but she added that city officials think the land is safe for development.

“We live in a mountainous community and therefore landslides are unfortunately an unavoidable risk,” wrote Jamie Fabos. “However, these landslides have caused very little movement over many years and development can successfully take place on landslide susceptible areas if the appropriate mitigation measures are identified and followed.”