GEOLOGY

Detailed explanation-1: -A tsunami is a series of waves. Often the initial wave is not the largest. In fact, the largest wave may not occur for several hours. There may also be more than one series of tsunami waves if a very large earthquake triggers local landslides, which in turn trigger additional tsunamis.

Detailed explanation-2: -To put the size of the massive wave into perspective, the second largest tsunami ever recorded was in Washington State in 1980. The run-up was about 820 feet, which is less than half the size of the Lituya Bay tsunami.

Detailed explanation-3: -The first recorded tsunami occurred off the coast of Syria in 2000 B.C. Since 1900 (the beginning of instrumentally located earthquakes), most tsunamis have been generated in Japan, Peru, Chile, New Guinea and the Solomon Islands.

Detailed explanation-4: -A megatsunami is a tsunami with an initial wave amplitude (height) measured in many tens, hundreds, and possibly up to thousands of metres. A megatsunami is a separate class of event from an ordinary tsunami and is caused by different physical mechanisms.