An earthquake which measured 5.2 on the Richter scale shook several parts of Mahar- ashtra in western India on 5 September. The epicentre was close to the 1000MW Koyna dam in the quake-prone region of Warna.
The earthquake lasted for approximately five seconds and was followed by an aftershock which measured 3.5 on the Richter scale and lasted for 20 seconds. According to official sources, the Koyna dam has not been damaged. Eight aftershocks of minor intensity have also been reported in the area.
The Koyna region is well known for its seismic activity. In 1967, the area was struck by a devastating earthquake which measured 6.5 on the Richter scale and caused parts of the Koyna dam to crack.
Due to the availability of field data from this event, the dam has been the subject of a number of studies in recent years. The University of Wales in Cardiff, UK, is currently modelling the dam to investigate its response to changes using numerical concrete cracking models. The study aims to derive a concrete cracking model which allows for cyclic loading and produces results that closely match experimental data.