Hawaiian mega-tsunamis with 1000 ft waves Dec 07 2012
Scientists have found evidence of mega-tsunamis hitting the Hawaiian islands that were more than 1000 feet high. The tsunamis are caused by landslides from collapsing volcanos but don't occur very often (every 100,000 years).
There are at least 15 giant landslides that have slid off the Hawaiian Islands in the past 4 million years, with the most recent happening only 100,000 years ago, according to the U.S. Geological Survey. One block of rock that slid off Oahu is the size of Manhattan.