In a span of over one month Chikkaballapura – located around 65 km from state capital Bengaluru – has reported five mild earthquakes.
The mines and geology department officials Thursday visited the Kamabalahalli and Bullsandra villages, a day after tremors were reported from the said areas. Government officials had to camp on site to assure the villagers of safety as five such incidents have been reported in the district so far.
The tremors on Wednesday were the latest in a series of mild earthquakes. Chikkaballapura was hit by two 3.0 magnitude earthquakes on December 22. The first earthquake had a magnitude of 3.1 and occurred at 7.09 am. The second earthquake, at a magnitude of 3.4, hit the area five minutes later at 7.14 am.
Another earthquake was reported at 2.16 pm on December 23 with a magnitude of 3.6 on the Richter scale. On January 5 an earthquake, measuring 2.7 on the Richter Scale, hit the district again.
While no casualties or major damages have been reported, cracks were found on the walls of some houses. Following the frequency of the quakes, the state government directed the Karnataka State Natural Disaster Monitoring Centre (KSNDMC) and the mines and geology department to look into the matter.
KSNDMC director Manoj Rajan said, “All the incidents reported in the district were of mild scale and tremors were felt up to a radius of 20-30km from the epicentre. No one was injured during these incidents, however, slight shaking of the buildings have been reported.”
“This falls under hard rock granitoid and gneissic terrain of seismic zone II. Scientists are studying Chikkaballapur and they have also recommended the National Geophysical Research Institute to carry out studies in the region,” he said.
A senior officer of the KSNDMC, on the condition of anonymity said that the recent earthquakes were caused due to the heavy floods that the district experienced.
“The district is drought prone and the rain in this region has been limited. But, last year the district witnessed heavy floods. When such unexpected amount of water comes to traditionally drought-prone areas, water enters fractured zones, which could be as deep as 10km, resulting in the movement of loose rock and eventually in these tremors,” the official explained.
Voicing the same opinion, an official from the mines and geology department, who was overseeing the survey in the district, said due to heavy rains reported last year, defunct borewells and other water bodies were filled quickly. “The water entering crust of the earth, which is called hydro-seismicity, causes these incidents in the district,” said the official.
Refuting the government claims, the local residents however alleged that rampant illegal mining in the district is the reason behind the numerous tremors in the district.
Meanwhile, satellite images sourced from the National Remote Sensing Centre, the department of mines and geology (DMG) and the Indian Institute of Science (IISc) had identified 532 illegal quarries in the Chikkaballapur district in 2019.
The findings were mentioned in the comptroller and auditor general (CAG) report as well, in which DMG was asked to take action against these illegal quarries. According to the report, at least 11.12 crore metric tonnes of specified and unspecified minerals were illegally extracted, causing a loss of ₹223.25 crore to the state.
A DMG official meanwhile said, “Around 450 licences have been issued for decorative stone quarries and 300 for stone quarries. But there are way more quarries. As per our estimate, there could be more than 2,000 illegal quarries across Karnataka.”
Minister-in-charge of the district, Dr K Sudhakar, said even though the tremors are caused by the underground water, strict action will be taken against the miscreants involved in illegal mining and those violating rules .
“We have had few incidents in the past where the tremors have been felt in some villages in the district. As per the experts, the sudden rain in recent times has resulted in these incidents… now those who are involved in mining should employ controlled blasting. I have told the police to take action against the people who are violating these norms and using such explosives which go against than the regulations,” said Sudhakar.