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Tsunami
‘warning’ was on Internet before it hit Lanka The GSMB has had the benefit of receiving data from the United States Geological Survey (USGS) since 2001 but on that ill fated December 26, the data on the origin, depth and magnitude of an underwater earthquake off the coast of North Sumatra reached the Bureau three hours after the incident, before the tidal wave hit the island. By that time the tsunami that was triggered by the earthquake had already begun slamming into Sri Lanka's coastal belt. Yet had the data arrived on time, the Bureau was still not geared to handle it. Such a report even if it came in early, it would not have given notice of a threat of incoming tsunamis, GSMB Director Sarath Weerawarnakula said. The GSMB has had the benefit of receiving data from the United States Geological Survey (USGA) since the auxiliary seismic station was set up in Pallekele in Kandy in 1999 became operational in 2001. The data relayed by this station is transmitted to the GSMB in Dehiwela and then to the University of California earthquake monitoring station and once analysed it is relayed back to Sri Lanka through the USGS, Mr. Weerawarnakula said. Sri Lanka has been a signatory to the Comprehensive Test Ban Treaty Organization (CTBTO) since 1996 and this has enabled the sharing of seismic data by Sri Lanka and is recipient of such data. However even though data on the magnitude and origin of seismic activity in the region is received by the GSMB, information on tsunami threats are not relayed as Sri Lanka like some other countries in South Asia are not members of the International Tsunami Information Center (ITSC). The GSMB has been alert about recent tremors in the country. On December 19, a tremor was experienced in some parts of the country. This measured less than 3.0 in magnitude but a report on it was submitted to the Ministry of Environment and Natural Resources, Mr. Weerawarnakula said. On D-day, a tremor was felt in most parts of the country around 7.05 in the morning. The GSMB had acted swiftly to check if the relevant data had been relayed to California via e-mail to confirm if they received the data, he said. However geologists at the GSMB had monitored the graph of the seismic activity but they had concluded that there was no cause of alarm, as the graph they read had not indicted any unusual seismic activity. By the time analysis of the magnitude and origin reached the GSMB, the tsunamis had already struck Sri Lanka, the Director said. As data from three monitoring stations in the area is needed to analysis any seismic activity, the process can take between one to three hours. The ITIC Tsunami Bulletin Board posted on the International Coordination Group for the Tsunami Warning System in the Pacific web page about 15 minutes after the quake, at around 7.14 am local time, placed its magnitude at 8.0 and its evaluation was "This earthquake is located outside the pacific. No destructive tsunami threat exists based on historical earthquake and tsunami data". It's next bulletin around 8.04 am local time said, "There is a possibility of a tsunami near the epicentre" and upgraded it's magnitude to 8.5. in it's next bulletin. It was several hours later that the magnitude of the earthquake was upgraded to 9.0. The first tsunami hit the Ampara district and within half an hour to 45 minutes affected the southern and western coastal areas of the country. The bulletin that upgraded the magnitude of the earthquake to 9.0 came on Monday night around 9.30 p.m. By that time the tsunamis had taken its toll across Sri Lanka and several other Asian countries. |
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