Chennai, Dec. 14: Patterns in the distant skies do have a link with tumults deep down in earth.

In the wake of the confusion over the recent quake alert in Upper Assam, researchers in Madras University?s department of applied geology today said planetary configurations could be ?definitive means of earthquake prediction?. The researchers, led by N. Rajeshwar Rao and N. Venkatanathan, claimed that based on planetary alignments, tremors could be predicted ?with fair accuracy? at least a month in advance.

It was Venkatanathan?s paper on this topic at a conference in Hyderabad that had triggered the alert, making thousands of Upper Assam residents camp outdoors at night two days ago.

Rao and Venkatanathan today told The Telegraph that in 1974, US astrophysicist John Gribbin had explained this concept in his book The Jupiter Effect. Gribbin, they pointed out, had said that when two or more planets ?aligned more or less in line with the earth?, the latter was ?caught in the middle of a huge gravity struggle between the Sun and the planets, especially the giant planet, Jupiter?.

Three planets ? Uranus, Neptune and Pluto ? were not taken into consideration as they were farthest from the earth. But when other planets aligned with the earth, the stress created by that process could ?change the speed of the earth in its orbit?. In such a situation, Gribbin, they said, had warned that the centre of the solar system could shift and the geological fault lines ?rip open, causing earthquakes?.

The researchers have downloaded a software that gives the planetary positions for any moment in a day. They are now working to determine three other key parameters ? the distance of the epicentre from the planetary position, the direction of the force acting on the possible epicentre and the ?angular momentum? (the little increase or decrease in the speed of the earth).

After analysing earthquake data of the last 100 years ? provided by the US Geological Survey ? Rao and Venkatanathan said they were able to arrive at what is called a ?mean triggering distance? of 626.125 km. It means that for every 626.125 km on the earth?s surface, there is a possibility of an earthquake, and they accordingly plot the hot spots on a map depending on the other parameters when planets align with the earth.

Taking into account the other key factors, the researchers claimed they were able to carry forward Gribbin?s insights for a ?much more accurate prediction of earthquakes?.

The department of applied geology has been making and testing such quake predictions based on this method for the past eight months with a success rate of 60 to 70 per cent, Rao and Venkatanathan said. However, they added, for all the predictions, ?we give an allowance of three days both ways because we do not know the structural geology of a particular area that also influences the time and intensity of the quake?.

The prediction for Assam was part of a series of other predictions for the period between December 9 and 15 and the magnitude they had given was 5 to 6 on the Richter scale. The predicted date for Assam was December 12, with the possible epicentre being 100 km from Dibrugarh. But it occurred three days earlier (on December 9), 288 km from the predicted place and measured 5.4 on the Richter scale.

But they pointed out that the other predictions they made for the same period, as for instance in El Salvador, the Bismarck Sea and Virgin Islands, the tremors were felt round about the same date as predicted initially.

In some cases, as in Virgin Islands and Vanauti Islands (near Fiji), the quakes took place exactly on the dates (December 11 and December 10, respectively) predicted, they added.