SHILLONG: It takes a big jolt to shake citizens out of their complacency. But repeated tremors in the past two days have put people on notice. The tremor that shook Shillong at dawn on Monday was serious enough to make the authorities of a local school do an earthquake drill. Children were asked to take shelter under the table and told that was what they should do in case an earthquake strikes. As per data received from Upper Shillong Central Seismological Observatory (CSO), in the last nine years, from 2000 to 2008, as many as 187 tremors have shaken Shillong city. These could portend a major earthquake in the region and the authorities concerned as well as public should sit up and join hands to prepare to face any eventuality, some seismologists said. The latest seismic wave that jolted the city at 4.12 am of Monday was recorded as 5.3 on the Richter scale. There was, however, no report of any casualty or damage to property from anywhere. According to Met In-charge of Upper Shillong CSO AC Lyngdoh, the epi-centre of the tremor was located at 23.6 degrees north latitude and 94.7 degrees east longitude on Indo-Myanmar border. On Sunday last, a tremor measuring 4.8 on the Richter scale shook Shillong at 0.22 am with its epicentre at 24.8 degrees north latitude and 90.6 degrees east longitude in Indo- Bangladesh border region. Shillong, the capital of Meghalaya, is located in the highest risk zone of earthquake vulnerability in India. As per Upper Shillong CSO data, 187 tremors were recorded between 2000 and 2008 in Shillong. The area has also experienced several earthquakes, including a major one that occurred in 1897, during which most of the town was destroyed. In last few years, several high-rises have come up in Shillong. Population pressure has resulted in construction of multi-storeyed residential flats. In fact, several buildings have violated the building bye-laws of Meghalaya Urban Development Authority (MUDA). There is scant respect for earthquake-proof specifications from seismologists. During an earthquake the lower part of a building tends to vibrate as it is in direct contact with the ground. The forces of inertia, however, keep the upper portions static. This conflict of forces leads to collapse. Most new constructions with heavy roofs (slate tiles or RCC) supported by weak walls prove deadly. No building can remain entirely free of damage during a quake. When an earthquake hits any city, more people die from being buried under the debris of buildings that collapse than from the quake itself. Going back to history, the 1897 earthquake holds a special place in the history of seismology. The buildings that survived the earthquake included some traditional Khasi houses. Earthquake resistant features exist in traditional constructions in Shillong, which could be useful in building better earthquake resistant houses in modern times, especially for rural and urban poor settlements in earthquake prone countries Several earthquake-prone regions in the country have traditionally built houses that minimise the damage to life and property and stand up well when the quake hits. Traditionally-built timber houses or even those with bamboo walls plastered with lime and sand have proved to be the most effective in keeping damage to a minimum. Year No of tremors 2000 17 2001 23 2002 15 2003 14 2004 16 2005 38 2006 23 2007 26 2008 15 Total 187 (Data from CSO, Shillong)