A 5.1-magnitude earthquake struck Arunachal Pradesh's Upper Siang district early on August 6, data released by the National Center for Seismology (NCS) showed.
This was the biggest one in a series of tremors that occurred in quick succession. There were no immediate reports of casualties or damage to property, officials said.
The 5.1 tremor was recorded at 5:45 am at a shallow depth of 11 km. The epicentre was located about 116 km north-northwest of Pangin in Upper Siang district.
It was preceded by multiple low-intensity tremors over the course of the early morning, indicating heightened seismic activity in the area before the main quake.
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NCS data showed that the first foreshock, measuring 2.8 in magnitude, occurred at 3:40 am at a depth of 5 km. It was followed by a 3.2-magnitude tremor at 3:55 am and another 2.8-magnitude event at 4:34 am.
Seismic activity continued after the main quake, with a 3.5-magnitude aftershock recorded at 7:17 am at a depth of 5 km, marking several hours of consecutive tremors in the region.
Authorities said they were monitoring the situation, while confirming that no injuries or structural damage had been reported immediately after the earthquake.
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Arunachal Pradesh is among India's most seismically active states and falls within Seismic Zone-V, the country's highest earthquake hazard classification. The region is prone to frequent tectonic activity because of the complex geological structures and active fault systems associated with the Eastern Himalayan belt.
Seimology experts have long identified the Northeast as one of India's most earthquake-prone regions, with recurrent seismic events resulting from the ongoing collision between the Indian and Eurasian tectonic plates.
