Water studies can predict quake'
Vibhor Mohan
Tribune News Service

Palampur, April 5
Lucknow-based experts of the Geological Survey of India (GSI) have
pointed out a detailed study of the underground water
characteristics can play a significant role in giving precursory
signals of impending earthquakes, even though forecasting of tremors
with accuracy still leaves much desired.

On the second day of the seminar organised by the GSI to commemorate
the centenary of the major earthquake that hit Kangra district, the
joint research work of S.N. Pandey, Hemant Kumar and Krishna Singh
highlighted that the irregular chemical behaviour of the spring and
underground water after an earthquake in an active seismic area
suggest a precursory signal.

Therefore, regular and systematic monitoring of the springs and
underground water samples can be an important parameter for
earthquake prediction, they said.

The monitoring of radon (a radioactive gas produced by the decay of
radium) in ground water on a regular basis was done near Amritsar
for six months way back in 1987-88. The anomalous change in radon
concentration was recorded on December 23, 1987, with a peak value
three times higher than the average.

According to the experts, two successive earthquakes of magnitude
4.5 each followed the increase on December 24-26, 1987, having their
epicentres in the Kangra area, 150 km from the monitoring site.

Several relatively small radon peaks were recorded during the last
days of February 1988 and were followed by an earthquake of
magnitude 4.2 on March 19, 1988, again having epicentre in Kangra
valley. Another noticeable radon anomaly was again recorded on May
10, 1988, that was followed by an earthquake of 4.8 magnitude with
its epicentre at about 400 km in the Hindukush range.

The chemical behaviour of springs and underground water in the
active seismic area shows there is drastic modification in water
quality after the earthquake. These changes in the water quality
depended on the distance of the spring from the epicentre and the
magnitude of the earthquake, said the experts.

Radon concentration in ground water is the most studied parameter
for earthquake prediction. Anomalous changes in radon concentration
in ground water have also been reported for several earthquakes, say
the seismologists.

They added that enrichment of carbon dioxide in thermal water also
acts as a precursory signal of an earthquake. The presence of CO 2
rich springs may indicate a potentially hazardous seismic region and
regular monitoring of CO 2 discharge could be useful in earthquake
prediction.

It was found that the chemistry of these hot springs displayed
significant changes in the post-quake scenario. Discharge
temperature of hot springs showed marginal decrease after the
earthquake and specific conductivity of the discharge water showed a
general decreasing trend.