Two more seismic wave monitoring centres

Shirley WIJESINGHE and Lakshmi DE SILVA

The Geological Survey and Mines Bureau (GSMB) will establish two more seismic wave monitoring centres at Mahakanadarawa, Anuradhapura and Hakmana before the end of this year, to enhance the measuring capacity of earth tremors.

A GSMB official told the Daily News yesterday that at least three seismic data recordings are needed to measure the exact intensity of a tremor, its location and map its occurrences.

The official added that the German Government will provide financial assistance for the project.

Suitable land sites for the proposed centres are being sorted out and acquisition of lands will be finalised shortly, he said.

A seismic wave monitoring centre operates in Pallekele. Data from a single centre is not sufficient to get accurate readings of seismic waves of earth tremors.

Meanwhile, earth tremors like the one experienced on Wednesday were caused by seismic movements of tectonic plates. "However, since we are placed in the centre of the Indian tectonic plate it is very unlikely to experience extensive damages from a direct impact of an earthquake," Geological Survey and Mines Bureau Geo Physicist, Nilmini Thaldena told the Daily News yesterday.

Sri Lanka has experienced several earth tremors in the recent past. A tremor felt around Moneragala on July 7, 2007 was due to a quake in the Bay of Bengal at a magnitude of 5.0 on the Richter scale some 400 kilometres away from Batticaloa. Exact sources of several tremors felt in Beralihela, Tissamaharamaya area (September 2007) was not known. Also these tremors were not stronger than a Magnitude of three on the Richter scale, she said.

During last year, tremors were reported from Sigiriya on April 4, Tangalle on August 6 and Diyatalawa on October 23, she said.

Though several other moderate earthquakes took place in the Indian Ocean region South of Sri Lanka, it is believed there is a defused plate boundary in the making some 500 km south of the southern tip of Sri Lanka was the cause of those quakes. "But any damage that could be caused to us from this regional setting is minimal as most earthquakes that occurred were below or around the Magnitude 5.0 on the Richter scale."