Magnitude 4.9 earthquake in Chamoli sends tremors across northern India

A magnitude 4.9 earthquake struck Uttarakhand’s Chamoli district on Tuesday night, sending tremors across parts of northern India, including Delhi and adjoining areas. India’s National Centre for Seismology (NCS), the government agency responsible for monitoring earthquakes, recorded the event at 10:23 p.m. and placed it 13 kilometres below the surface.

The Hindu reported that the epicentre was in Chamoli district. India Today gave a more specific preliminary location, about 22 kilometres from Khadun Laga Gawali in the Gairsain area of Chamoli. The reports agree on the magnitude, timing and depth, but the NCS’s final parameters will be needed before the location and source are settled more precisely.

Tremors were reported in Delhi-NCR and across parts of Uttarakhand, Himachal Pradesh, Punjab and Haryana, according to India Today. NDTV said people in Delhi and neighbouring areas described their experiences on social media. The supplied reports did not give details of damage, casualties or emergency response.

The earthquake occurred in the Garhwal-Kumaon Himalaya, one of India’s seismically active regions. India Today said the area is shaped by the continuing collision of the Indian and Eurasian tectonic plates, with several major geological structures influencing how stress is distributed beneath Uttarakhand. One of those structures is the Main Central Thrust, which separates the Lesser Himalaya from the Higher Himalaya.

Researchers have found that many earlier Uttarakhand earthquakes occurred near it. However, India Today said scientists could not yet attribute Tuesday’s earthquake specifically to that fault. The deeper Main Himalayan Thrust accommodates much of the tectonic convergence, while the region also contains the Main Boundary Thrust, Himalayan Frontal Thrust, Moradabad Fault and Great Boundary Fault.

India Today said earthquakes in the Garhwal-Kumaon region occur at shallow to intermediate depths within this complex network. Scientists will need the final NCS measurements, including a more precise epicentre, depth and focal mechanism, to determine which fault slipped. The NCS operates a nationwide network of more than 170 seismic stations, according to India Today, and its preliminary reading may be refined as further data are assessed.

India Today characterised the event as moderate and said tremors across northern India do not, by themselves, indicate that a larger earthquake is imminent. Uttarakhand has experienced damaging earthquakes in the past, including the 1991 Uttarkashi earthquake and the 1999 Chamoli earthquake, but the reports supplied no indication that Tuesday night’s event has been linked to an impending major quake.