2004 Banda Acheh Earthquake
Tsunami is the Japanese word for harbour wave; a sequence of rapidly moving waves of extremely long wavelength generated primarily by an earthquake occurring below and close to the ocean floor. Although relatively infrequent, tsunamis are one of the Earth's most powerful forces, with a magnitude and scale of destruction that tests the limits of one's imagination.
One of the most devastating tsunamis that has ever been recorded occurred on December 26, 2004. This event was estimated to be the ninth deadliest natural disaster in modern history. The coastal countries of the entire Indian Ocean were affected, with Indonesia, Sri Lanka, India, Thailand, and Myanmar enduring the greatest impact. The earthquake that caused the tsunami covered an extremely large geographical extent. An estimated 994 miles (1,600 km) of faultline slipped about 50 ft (15m) along the subduction zone where the India Plate slides under the Burma Plate. The tectonic slip did not occur instantaneously, but took place in two phases over a period of several minutes. India and other countries in the northern part of the Indian Ocean experienced significantly lower levels of destruction than in southern Indonesia and Thailand. The northern shift occurred a few minutes after the more powerful southern shift, and was much slower. This difference reduced the speed of the water displacement and subsequently reduced the size of the tsunami in the north. A Tsunami early warning system and precious time would have saved the lives of thousands of people in this region.
Local Geology
There are two active tsunamigenic zones in the vicinity of India: the Andaman-Sumatra trench along the east coast and the Makran subduction zone in the western part of the country, north of the Arabian Sea. Following the UNESCO response to the 2004 Indian Ocean Tsunami, the Government of India recognized the pressing need for a Tsunami early warning system.
In May 2007, the Government of India contracted Nanometrics for the "Establishment of a National Early Warning System for Tsunami and Storm Surges in the Indian Ocean". Subsequently on October 15th of 2007, a new Nanometrics National Tsunami Early Warning Center opened in Hyderabad. A total of 17 interconnected broadband Nanometrics seismic stations were established throughout the country for real-time data communication both to the Central Receiving Station of the India Meteorological Department (IMD) in New Delhi and the National Tsunami Early Warning Center at INCOIS in Hyderabad. Commissioned by the Ministry of Earth Sciences of India, the state-of-the-art Center was set up by the Ministry's daughter organization, the Indian National Center for Ocean Information Services (INCOIS).
Seismic Network
The National Tsunami Early Warning Center comprises the observing systems for real-time monitoring of the seismic activity and sea level changes: communication of real-time data from the observing stations; computational infrastructure for enabling data reception and sharing; online display, database management, decision support; and, generation and dissemination of advisories. The project had been identified by the Government of India as a priority in its agenda for 2005-2007.
The hardware segment of the system comprises a network of Nanometrics based seismic stations, bottom pressure recorders, tidal stations, coastal radars, and automatic weather stations. The system can automatically detect and locate earthquakes of magnitude greater than 3.5 in the Indian Ocean region. The automatic processing system provides a full-range of magnitudes, including Ml, Md, Mwp, Mb, Ms, MbLg, MT, and CMT magnitude modules.
All 17 stations are currently installed and fully commissioned.
For more information on the seismotectonics of India:
Nanometrics real-time seismic network monitoring equipment is to be used exclusively in the Indian National Early Warning Systems for Tsunamis. A total of 17 interconnected broadband Nanometrics seismic stations were recently established throughout the country for real-time data communication both to the Central Receiving Station of the India Meteorological Department (IMD) in New Delhi, and the National Tsunami Early Warning Center at INCOIS in Hyderabad.