How the 2004 Indian Ocean quake transformed tsunami science

Context: December 26, 2024, marks the 20th year since the 2004 Indian Ocean
earthquake and tsunami. The tsunami generated by the quake of magnitude 9.1 was
sourced off the Sumatran coast and was the third largest (by magnitude) in the
world since 1900. The source was 30 km below the ocean floor, in the Sunda
trench, where part of the Indo-Australian plate subducts beneath the Burma
microplate, which is a part of the Eurasian plate. The 2004 earthquake ripped
through 1,300 km of the plate boundary, the fault tearing from Sumatra in the
south to Coco Islands in the north. The quake was felt in Indonesia,
Bangladesh, India, Malaysia, the Maldives, Myanmar, Singapore, Sri Lanka, and
Thailand, the overall death toll was around 227,000 and more than 1.7 million
people displaced.

Key points

·       Overview: A magnitude 9.1
earthquake near Sunda Trench (Indonesia) in 2004 triggered Indian Ocean tsunami
that devastated almost14 countries. Sunda Trench is situated on Pacific
"Ring of Fire" (Arc of intense seismic activity stretching from Japan
through Southeast Asia and across Pacific basin).

·       Tsunami: Series of
enormous waves created by an underwater disturbance caused by violent seafloor
movement associated with earthquakes, landslides, lava entering sea, seamount
collapse, or meteorite impact.

·       Features
of Tsunami Waves: Not noticed by ships in deep oceans because their
amplitude is negligible when compared with their wavelength. Their speed
depends on ocean depth, not distance from wave's source.

·       UNESCO-IOC
Tsunami Ready Recognition Programme: Voluntary, international
community-based effort to bolster risk prevention across global coastal zones.

·       Tsunami United
Programme: Flagship initiative of UNESCO to increase preparedness.

·       Global
Tsunami Early Warning and Mitigation Programme: IOC-UNESCO Programme
supports Member States in assessing tsunami risk, implementing Early Warning
Systems etc.

·       Indian
Tsunami Early Warning Centre (ITEWC): Established at Indian
National Centre for Ocean Information Sciences, Hyderabad is national authority
to issue tsunami advisories.

·       Indian
National Centre for Ocean Information System (INCOIS): INCOIS was
established in 1999 as an autonomous body under the Ministry of Earth Sciences.
INCOIS through Indian Tsunami Early Warning Centre (ITEWC) is the nodal agency
to provide tsunami advisories to India. It is coordinating with the Disaster
Management Officials (DMOs) for implementation of Tsunami Ready programme in
India.

·       Recent
Focus in Tsunami Warning Capability: The focus in recent times
has been on enhancing community awareness and response through several capacity
building activities, biennial Indian Ocean wide tsunami drills and piloting of
the UNESCO-IOC Tsunami Ready initiative.

Ø  Tsunami Ready is
a community performance-based programme to promote tsunami preparedness through
active collaboration of public, community leaders, and national and local
emergency management agencies.

Ø  The main
objective of this programme is to improve coastal community's preparedness for
tsunami emergencies, to minimize the loss of life and property and to ensure a
structural and systematic approach in building community preparedness through
fulfilling the best-practice indicators.

Ø  Two villages of
Odisha, Venkatraipur in Ganjam district and Noliasahi in Jagatsinghpur district
are now ‘Tsunami Ready’.

·       Way
Forward: Initiatives like Tsunami Ready must be replicated in other vulnerable
coastal communities as it enhances ability to respond to cyclones and storm
surges too. The best of warning systems could fail, if communities are not
prepared, if they do not understand the official and natural warning signs of a
tsunami, and if they do not take appropriate and timely response.