The series of tremors in Bidar and Kalaburagi districts in North Karnataka were related to a phenomenon called hydro-seismicity, which occur post-monsoon, revealed a preliminary study by NGRI.
"We had asked the National Geophysical Research Institute (NGRI) to take up a detailed analysis of the micro tremors that we are experiencing in Kalaburgi and Vijayapura region," Karnataka State Disaster Management Authority commissioner Manoj Rajan told PTI on Friday.
"Their preliminary observations indicated that the micro tremors of this nature normally occur during the post monsoon period. It is related to a phenomenon called hydro-seismicity after a heavy rainfall," Rajan said.
He also said that within crustal volumes having fracture permeability, a natural increase in hydraulic head due to the elevation of the water table in recharge areas of groundwater basins increases the stress in earth. This event triggers micro tremors and in some cases it is accompanied by sound, the officer said.
"These are due to shallow earthquakes that generate high-frequency surface waves. This type of seismic activity is very common and nothing to worry about, since it may not cascade into a large devastating earthquake," the officer said.
Rajan added that the NGRI is sending a team of scientists to these regions in the next two days to study and ascertain the field conditions. Villages near Basavakalyan in Bidar and Chincholi in Kalaburagi witnessed at least six tremors ranging between 2.5 to 4 magnitude on Richter scale from October 1 to October 12.
While most of the panicked villagers spent their night under the open sky fearing a major earthquake, a few others went to some other place till things are normalised.
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