A 12 million cubic meter landslide occurred in Wulong county in southwest China’s Chongqing Municipality on Friday. There are some excellent blog posts on this rockslide at Dave’s Landslide Blog. This massive failure occurred in the vicinity of a mine (Iron ore?) being run by a private company since 2004 after Chinese government geologists labeled the site dangerous resulting in it being closed in 2000 after over 50-years of production. (Photo from Suomen Kuvalehti via Dave’s Landslide Blog)
On March 21, 2008 a landslide caused the closure of Arizona State Route 87 between Payson and Phoenix near mile post 224. So far there are no official estimates as to the size, but based on aerial photos, it appears to be at least 50,000 sq-ft in plan. The offset at the head scarps was approximately 2-meters (6.6-ft) according to AZGS Geologists on site. It appears to have been a rotational slide as the toe of the landslide heaved the southbound roadway up by as much as 1-meter (3.3 ft). There was an existing soil-nail retaining wall on the slope that was destroyed by the slide as well. Lateral deformations can be seen in photos of the median barrier and the roadway striping. The deformations extended into the northbound lanes as well. More photos and links after the break. (Photo by ADOT)
The Utah Geologic Survey has released a "Landslide Susceptibility Map of Utah". They apparently relied quite heavily on GIS based thresholding of existing slope angles but only after they had statistically analyzed failure angles for particular geologic units. So it sounds like they throw the known landslides, the geologic map of Utah and a DEM into the GIS a blend it all up. Perhaps a slight oversimplification!