Kerala: Sinking wells give creeps

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Kochi: Kerala is once again witnessing the phenomenon of disappearance or sinking of wells on a large scale since the onset of the monsoon this year. According to unofficial estimates 250 wells have ‘disappeared’ in the past one month in the central and northern districts of Thrissur, Kannur, Kozhikode, Malappuram, Wayanad and Kasargod.
No serious study has been done to find out why this is happening. Accor­ding to geo-enthusiast and Ham Radio operator Sreemurugan Anthikkad, who has been closely following this phenomenon, thousands of wells have slowly disappeared since this phenomenon began in 2001, but this is the highest incidence in a month. He says that this phenomenon occurs only in Kerala and mostly in north Kerala.
“From newspaper repor­ts and internet sites I cou­ld collect data about the disappearance of over 160 wells in the past one mo­nth. The actual figure is more, since the media los­es interest if it recurs in the same place,” he says.
According to the Centre for Earth Science Studies, Kerala has had 116 minor earthquakes between Ja­n­uary 2012 and April 2013, and 33 per cent have occ­ur­red in Thrissur district.
“I strongly believe that the phenomenon (of the disappearing wells) is related to the earthquakes. The sudden spurt in such incidents seems to suggest that uncontrollable cumulative pressure is gathering inside the earth. Twenty-six wells caved in, in Thrissur the other day.
This calls for a scientific enquiry to ascertain whether this is indicative of an imminent earthquake as normally, pressure accumulates in­s­ide the earth before an imminent earthquake. It has to be found out if pressure is released through this phenomenon. There has been a perceptible increase in seismic activity since 2012 in the state. However this phenomenon is not given the attention it deserves,” Anthikkad said.
In earlier times there were ‘kitchen wells’— wells attached to the kitchen to enable women to draw water easily for cooking and other purposes. Anthikkad says that in those days this phenomenon of sinking wells was not reported. He claims that it was after the massive Bhuj earthquake in Gujarat in January 2001 that this phenomenon was reported in Kerala.
“Prior to this quake, a quake measuring 4.5 on the Richter scale was reported with Pala as the epicentre, in December 2000,” he said. According to Dr John Mathai of CESS, this phenomenon may have existed earlier but was noticed only after the Bhuj earthquake and the smaller earthquakes in Kerala at that time.
Next: Heavy rains or seismic activity

Heavy rains or seismic activity
 Kochi: According to scientist Dr John Mathai of the Centre for Earth Science Studies, there are  two reasons for wells caving in. “The first happens when there is heavy rain and gushing  water and the soil on the sides exerts pressure. The second type happens when there is unusual pressure from the bottom.
The second type points to some unusual activity in the earth and we suspect it may be related to seismic activity. There is no study to either prove or disp­rove this,” he said.
He said a study of this phenomenon is necessary and geologists shou­ld be involved in it. Dr V.P. Dinesan, a hydrologist at the Centre for Water Resources Develo­p­m­ent and Management said that the institute has identified 10 reasons for the caving in of wells.
“Most such wells have a weak structure. It also happens in locations where the soil is weak. When movement happens to the lineament such occurrences take place. There is no one reason for it. Sometimes wells near railway tracks cave in,” he said.
Dr Dinesan too says a team of seismologists, hydrologists and geologists should probe the connection to seismic activity and possible indication of forthcoming earthquakes.
But Dr Narasimha Prasad, executive director of CWRDM, says there is no reason why there should be any relation between seismic activity and collapse of wells, unless it happens to many wells in a small area.
“The number is very small now. Basically, the phenomenon happens when the soil exerts pressure on the well and it collapses if it is old. When there was a large incidence of this in 2002, a team had visited the wells and arrived at this conclusion. If seismic activity takes place, it should not be confined to wells, it should affect houses also,” he reasoned.
He says he doesn’t know why the phenomenon is largely restricted to central and northern Kerala. “It’s easy for a well to cave in if just a brick or two goes, or a crack develops in the ring,” he said.
Hydrologist with the ground water department, Mr Varadarajan, says this type of caving in happens when a lot of rain falls over a small area. “The soil is not able to withstand it. Most of the wells that have caved in are old ones,” he said.