GSI prepares report for Centre

Kolkata: After the scary earthquake that shook up Myanmar and large portions of Eastern India on Wednesday evening, another one, touted to be an aftershock, shook Myanmar on Thursday morning. The Geological Survey of India (GSI), headquartered in the city, has identified and incorporated it in its report that it has sent to the ministry of mines. The aftershock was not felt in Kolkata because it was weaker than Wednesday's.
According to the GSI report, the intensity was 6.8 on the richter scale on Wednesday evening at 19:25:25pm (IST).The tectonic movement that caused the earthquake happened at a depth of 144km below the earth's surface.
Wednesday's earthquake occurred in the India-Myanmar wedge near Mawlaik in Myanmar. The Indian plate, which lies below the Eurasian plate, is under pressure. The constant tectonic movement causes stress on the Indian plate which tends to get released along the fault lines.
In case of Wednesday's quake, the two fault lines that gave up under the subduction of the eastward-dipping Indian plate are the Sagaing and Kabaw fault lines. "The quake happened at Sagaing in Myanmar. Since it happened so deep below the earth's surface, the effect was so far reaching. In Kolkata, the same intensity was felt within a fraction of a second. This is because the shock emanated deep underneath, making it travel fast. Since Kolkata lies on a bed of loose alluvial soil, the intensity is always on the higher side," explained director general of GSI, Harbans Singh.
On Thursday, an earthquake of much lower intensity, 4.4 on the richter scale, happened at 11:11:54 am (IST) at a depth of 40km. "The epicenter of Thursday's quake, which is basically an aftershock, is not too far from Sagaing," Singh said.
Incidentally, GSI had installed a Seismo Geodatic Data Receiving and Processing Centre in Salt Lake on April 12 to study tectonic movements across the world, round the clock. The report on Wednesday and Thursday's quakes was prepared on the basis of readings collected by this. on the advanced computerized machines that have been installed by the Centre.