A leading US-based researcher is of the view that the proposed Jaitapur nuclear power plant should be designed for future shaking of a magnitude of up to 6 on the Richter scale.
Occurrence of earthquakes of up to M6.5 on faults near Koyna and Latur at approximately the same latitude as Jaitapur is of considerable concern, says Dr Roger Bilham.
In a paper co-authored with Dr Vinod K. Gaur of the Council of Scientific and Industrial Research (CSIR) Centre for Mathematical Modelling and Computer Simulation, he said that the stress regime near Jaitapur cannot differ substantially from these two areas.
The paper has appeared in the journal Current Science .
The occurrence of the nearby Koyna earthquake has presumably loaded the Jaitapur region closer to failure as a result of ‘stress transfer,’ the authors said.
The apparent seismic quietness of Jaitapur does not mean that a severe earthquake cannot occur there.
If stress in the region is sufficiently mature to have brought an existing subsurface fault close to failure, an earthquake may be imminent.
“It is our opinion that insufficient data are available to exclude this possibility,” the authors said.
VULNERABLE STRETCH
“With the possible exception of Koyna and Latur, no shallow fault in the northern peninsula may be invulnerable to future rupture of M6 or greater,” they said.
An earthquake of M6.5 in the close vicinity (as in Koyna, Latur) may not occur for many thousands of years. It could, however, do so within the lifetime of the nuclear power plant.
As the recent earthquake in Japan has demonstrated, it is relevant to plan for all possible futures in the design of nuclear power plants.
Nuclear power stations can be engineered to withstand a high degree of shaking intensity, although the expense of the design increases with the severity and duration of the anticipated shaking.
The authors also agreed that estimates of seismic risk to the planned nuclear power plant assessed from a short dataset of only the past few centuries, may not represent the true risk to the plant.