I was wondering whether we might be able to help address this problem with technology. At the most basic I would imagine you would need data on angle of slope, soil type, precipitation, and land use. With that you might be able to generate a map of the most at risk areas, and can then target those areas with mitigation measures, whether that's hard engineering where possible, or even something as simple as sending out text messages when dangerous amounts of rain are forecast, kind of like a tsunami warning. Surely we can do better than letting hundreds of people die like this?
I found an interesting reference here: https://pubs.usgs.gov/circ/1325/pdf/Sections/Section1.pdf
30000 dead in Venezuela in 1999. Terrifying.