My deepest sympathies for this family and others impacted by this tragedy. But, I can't agree with the statement "I don't know how you prepare for something like this." From one of the articles cited:

"Another resident lingering at the roadside barriers, who declined to give his name, said sinkholes and landslides are common in this area of southern Quebec.

He blamed "blue glaze" a very soft type of clay that lines the banks of the Yamaska River.

Civil security officials said the home was sitting in a zone known to represent a risk of mudslides."

Yes, you can't personally prepare when the terrain collapses and swallows your house whole. But no, you can mitigate your risk by not building homes in areas subject to landslides, mudslides, sinkholes, etc. When you do, or when local ordinances allow it, residents have to accept the risk of something like this happening to them. Generally speaking this tragedy is not much different than wildfires consuming houses built on hillsides above Oakland, or in the valleys outside of LA, or taken out by mudslides in Seattle along Prentice Lane. These areas are known to be hazardous over time, but mostly over durations where folks - including city planners and zoning experts - can ignore or overlook the short term hazard of building and living in them.

A friend from Spain always marvels at our American ability to build houses on hillsides - such a thing has never been done in his part of Spain.