A tsunami is a series of large waves generated by an abrupt (আকস্মিক ) movement on the ocean floor that can result from an earthquake, an underwater landslide(ভূমিধ্বস), a volcanic eruption(আগ্নেয়গিরির অগ্নুৎপাত) or - very rarely - a large meteorite strike(উল্কা পাত).However, powerful undersea earthquakes are responsible for most tsunamis. Seismologists say only earthquakes measuring greater than 7.0 on the Richter scale can produce a major tsunami.