It is possible that Haiti will surpass the destruction of what until now has stood as the most devastating quake of the Western Hemisphere in modern times, the 1970 Ancash quake near Chimbote in Peru. At 7.7 (richter) the under coastal quake took out 80% of the structures in the affected area, killing an estimated 60,000 people and displacing perhaps half a million (but probably more) people. The quake also shook loose an 800 meter ice sheet on distant Mount Huascaran that in turn sent 80 million cubic meters of material crushing down on to the countryside below, and the city of Yungay disappeared (though later rebuilt, the original site of the city is a national cemetery). Huascaran is an angry spirit, having smashed the area in 1742 and 1962, making Yungay the dominate municipal area - essentially herding people into a central area and wiping them out in 1970. The Cristo (below) on the cemetery hill (along with the four palm trees below) were the only surviving features in the town of Yungay.
The settling of ground sediment caused massive destruction in Chimbote as well as flooding. Flooding was also made worse by the combination of settling and the avalanche: Rio Santa sent a 20 meter high wave down to coast for a distance of 150 kilometers, wiping out everything on its banks. Here are some pictures from the US Geological Survey of the area.