Introduction

Landslides, around the world, take a heavy toll on life and property every year. Indeed, they are one of the most significant contributors to loss of life and aggregate national losses caused by natural disasters associated with earthquakes, severe storms and heavy rainfall in mountainous terrain (Lundgren, 1986; Swiss Reinsurance Co., 2000). Sediment disasters by debris flows, mud flows, and landslides occur almost every year during the rainy and typhoon period of July to October in Japan. In July 1982, a heavy rainfall of 488 mm in a day caused 4300 debris flows in Kyushu Island killing 299 people. Many debris flows caused by intensive rainfall during July 1983, in Honshu Island killed 199 people.  Both created also enormous loss of property (Abe and Ziemer, 1990). Considered some of the worst ever natural disasters in Brazil, 806 people were killed and hundreds were yet to be traced killed as cloud-burst triggered avalanches of mud and water ripped through already water-soaked mountainsides in January, 2011 (Geology & Earth Sciences, 2011; Scientific American.com, 2011). The month also saw such disasters worldwide as floods and landslides caused devastation in Australia, China and Sri Lanka.