The correct option is (a).
Explanation
The 2004 Indian Ocean Tsunami was triggered by a massive undersea megathrust earthquake off the coast of Sumatra. The extent of the devastation was influenced by the magnitude of the seismic event as well as the preparedness levels of the affected regions.
Statement-wise Analysis:
- Statement 1 is Correct: In 2004, unlike the Pacific Ocean, the Indian Ocean did not have a functioning Tsunami Early Warning System. Consequently, despite the time lag between the earthquake and the tsunami striking distant coasts (such as India and Sri Lanka), no official alerts were disseminated to evacuate the population.
- Statement 2 is Incorrect: The coastal population was largely unaware of the indicators of an approaching tsunami. When the sea water receded (a typical precursor to the arrival of the massive wave), many people gathered at the shore to witness the phenomenon rather than moving to higher ground, which significantly increased the casualty count.
- Statement 3 is Incorrect: The earthquake was not of low magnitude. It was registered with a magnitude of 9.1–9.3, making it one of the most powerful earthquakes ever recorded. The immense energy released by this high-magnitude event was the primary physical cause of the tsunami.
Key Takeaway:
The massive destruction caused by the 2004 Tsunami was a result of the extremely high magnitude of the earthquake combined with the lack of institutional mechanisms (early warning systems) and public awareness regarding tsunami signs.