DOWNLOAD HERE: http://newsdirect.nma.com.tw/SingleItem.aspx?asset_id=OEM_20120126_OINT_002 When there is loose rock and soil, slopes become vulnerable to landslides. VO: There can be a variety of triggers, but the most common trigger is heavy rainfall, which further loosens the rock and soil. Vibrations from human activity such as quarrying can also trigger landslides. A landslide hit Papua New Guinea's Southern Highlands, killing at least 40 people. Another 20 people are missing. The landslide struck a remote area with several small villages.