Text of my ‘When Worlds Collide’ column published in Ceylon Today Sunday newspaper on 22 April 2012

To warn or not to warn — that was the question. On 11 April 2012, following a powerful undersea earthquake, government officials in many Indian Ocean rim countries agonised over this.

The 8.6 magnitude quake occurred at 8.38 UTC (14:08 Sri Lanka Time), 440 km southwest of Banda Aceh in Indonesia and 33 km beneath the ocean floor. That was relatively close to the location from where the devastating tsunami originated on Boxing Day 2004.

Earthquakes can’t be predicted, but once detected, they require rapid assessment and decision making, especially in maritime countries in case of a tsunami.

The Pacific Tsunami Warning Centre (PTWC) – a scientific facility of the US government, located in Hawaii – issued its first information bulletin six minutes after the 4/11 quake. It introduced an Indian Ocean-wide Tsunami…