On Friday, Colorado and federal geologists were still trying to determine what might happen next with the massive mudslide in the hills of Mesa County, on Colorado’s western edge. Heavy rainfall caused a half-mile stretch of ridgeline to collapse on May 25. The flow of mud extended for 3 miles and killed three men.

In the best case scenario, nothing will change. In the worst, several more miles of valley will be consumed by mud and debris. And it’s unclear which is more likely

At a community meeting late last week, “[L]andslide, water and disaster experts told Collbran residents Thursday that the massive slide above their valley is still a conundrum — and still a danger,” reported the Denver Post, “even though more than half a dozen devices are monitoring and measuring it and dozens of agencies across the state and country are studying it.”

Residents learned that the growing pond at the head of the slide was already 6 acres large (about 29,000 square yards) at its surface, an estimated 15 feet deep, and “dammed by an unstable block of debris [that] is the big unknown” for what could happen next:

“It’s been called a 10,000 year event and we’ve had 10 days to study it,” said one county official.

Geologists worked atop the slide last week to set up cameras and sensors that will monitor it for changes, reports the Post.

The initial mudslide was so enormous, and moved so fast, that it leapt its original channel to flow uphill and then down into an adjoining valley, as Colorado Public Radio reports in the video above.