Reported by Roopak Goswami
Guwahati: The magnitude 5.8 earthquake that struck near Bhutan’s capital Thimphu on June 7 was caused by movement along the Main Himalayan Thrust (MHT) system, underscoring the continuing seismic threat to the eastern Himalayas and Northeast India, according to a preliminary report by the National Centre for Seismology (NCS).
The earthquake occurred at 11:06 pm IST on June 7, with its epicentre located about 18 km north of Thimphu at a depth of 26 km. The tremor was widely felt across Assam, Meghalaya, Arunachal Pradesh, Sikkim, West Bengal and Bangladesh.
According to the NCS, waveform analysis showed a “pure thrust faulting” mechanism on a north-dipping fault plane, indicating that a splay of the Main Himalayan Thrust near the Main Central Thrust (MCT) was the likely rupture source.
The report notes that Bhutan lies on a locked segment of the Main Himalayan Thrust, where the Indian and Eurasian tectonic plates continue to converge at a rate of around 15–20 mm per year. This ongoing collision causes strain to accumulate beneath the Himalayas, creating conditions for future moderate to large earthquakes.
NCS said the June 7 event reached a maximum intensity of VII on the Modified Mercalli Intensity scale in the epicentral region and was felt up to 500 km away. The agency warned that the Bhutan Himalaya remains a region of persistent seismic hazard due to continued strain build-up along the MHT and its associated fault systems.
Data from the National Seismological Network showed that the strongest recorded ground shaking among listed Indian stations was at Tawang in Arunachal Pradesh, while lower peak ground acceleration values were recorded at Gangtok, Jalpaiguri, Guwahati and Bomdila.
The findings come as scientists continue to monitor seismic activity across the eastern Himalayas, one of the most active earthquake-prone regions in the world.