14 quakes in 2 months may not lead to a big one in NCR

nNEW DELHI: Wednesday night’s minor tremor in Noida was the fourteenth (14th) to hit Delhi and the National Capital Region (NCR) over the past two months, but the increased frequency may not necessarily indicate a major one is coming, say seismologists.

Still, monitoring them is key to being prepared , they add. Scientists at the National Centre for Seismology (NCS) underlined that earthquakes cannot be forecast and the only thing to do is to be aware of the activities in vulnerable pockets such as the Delhi region. Only two of the 14 tremors have been above magnitude 3.5, according to NCS data.

“While these [minor earthquakes] may be because of activity in the local faults, we have to remember that north Delhi is close to the Himalayan belt where the Indian plate is subducting under the Eurasian plate. That region is seismically very active. We need to monitor even these small earthquakes critically because we do not know how much energy is there and how much has been released through these small events,” said Kalachand Sain, who heads the Wadia Institute of Himalayan Geology. Subducting is the process by which one tectonic plate moves under another.

A P Pandey, an NCS seismologist, said there have been numerous small earthquakes in Delhi and Haryana over the past three years and that a few have been above magnitude 4. “There are many faults and fissures in this region which could be active. In the past three years, there have been numerous small earthquakes in this region. Luckily, we did not see a much bigger earthquake …we are close to the Himalayas. The Himalayan plate is moving in the north-northeast direction and subducting beneath the Eurasian plate. So, there is a lot of energy along weak zones which are sometimes released through fissures and lineaments.”

The Himalayas are vulnerable to major earthquakes. “Nobody can say when this energy will be released. So, it is best to be prepared,” Pandey said.

NCS head (operations) J L Gautam said it is not abnormal to record so many earthquakes within a couple of months in the Delhi-ncr region “There are a number of small faults in this region. The earthquake last [Wednesday] night was in Uttar Pradeshingautambuddhanagar. There is the Mathura fault, Moradabad fault, Delhi-haridwar ridge, Delhi-sargoda fault, Mahendergarh and Dehradun fault. So, small earthquakes happen in this area. It’s not abnormal.”

According to Indian Institute of Science’s seismic hazard mapping in 2004, the terrain of Delhi is flat in general except for the NNESSW trending ridge. “This is one of the prominent features of Delhi. This is considered as an extension of the Aravalli hill, which is buried under the Yamuna alluvium in the northern parts of Delhi. River Yamuna, which is another prominent feature of Delhi, enters the city from the north and flows southward with an eastern bend near Okhla. This path forms a tri-junction with the Lahore-delhi ridge and the Delhi-haridwar ridge. This region is seismically active and shows sporadic activity aligned in NNE-SSW direction, nearly perpendicular to the Himalayan arc. Proximity of Himalayan region makes Delhi susceptible to the earthquakes from Himalayan seismic sources also.”

INCREASED FREQUENCY OF SMALL QUAKES DOES NOT NECESSARILY MEAN A MAJOR ONE IS COMING, BUT MONITORING THEM IS KEY, SAY EXPERTS