Whose work first explained why earthquakes generate landslides in steep mountain regions?

There is no single person credited with discovering earthquake-triggered landslides, but geologists and seismologists built the explanation over time. Strong shaking can destabilize steep slopes, weaken rock, and cause massive landslides or debris avalanches. Major earthquakes such as the 1920 Haiyuan event in China and the 2008 Wenchuan earthquake showed how destructive this hazard can be. Landslides often cause as much devastation as the shaking itself. They are now a major part of earthquake risk assessment in mountainous areas.