Tiruvannamalai District experienced earth tremors on Thursday morning, September 26th, after a gap of nearly 25 years, according to the Centre for Disaster Mitigation and Management, VIT University, Vellore.
Vellore and Tiruvannamalai Districts have become seismically-active since 2002 and they have been reclassified into zone 3 (prone to quakes with up to 6.9 magnitude) from zone 2 earlier (up to 4.9 magnitude).
Last Thursday at Tiruvannamalai, residents of Pudu Theru (i.e. Theru = Street), Pey Gopura Theru, Muthuvinayaga Theru and Mathalangula Theru; came out of their homes after the vessels in their houses fell down at about 8.20 a.m., as they feared more serious tremors. No damage to property or life has been reported. Residents returned to their houses only after ascertaining that there were no aftershocks.
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| Thiruvoodal Theru leading to Pey Gopura Theru |
The Indian Meteorological Department reported the Tiruvannamalai earthquake to measure 3.3 on the Richter scale and lasted for about three to five seconds. The epicentre of the Tremor is suspected to be in the Polur and Tiruvannamalai region, where an existing fault (planar rock fractures) passes from Salem to Tiruvallur.
Earth tremors are a common phenomenon restricted to local conditions due to the readjusting of faults. In this respect around 105 tremors have occurred in Tamil Nadu in the last 200 years, with the majority measuring less than a magnitude of 5. Only a few of the earth tremors had a magnitude of more than 5; which included an earthquake in Coimbatore in 1900 (magnitude of 6) and one off the shores of Pondicherry in 2001 (magnitude 5.6). There are estimated to be around 286 fractured faults in Tamil Nadu, of which only around 47 have been found to be active.
Tiruvannamalai District has only witnessed five tremors in recorded time. The first major one recorded was in 1822 at Vandavasi with a magnitude of 5, and later between Polur and Tiruvannamalai with a magnitude of 5. The same region witnessed another tremor in 1984 that had a magnitude of 3.3.
