Why Nepal earthquake was felt from Vadodara to Vijaywada?

New Delhi: The impact of the 6.3- magnitude earthquake that struck the lower Himalayan region and killed at least 6 people due to a house collapse in the Doti district of Nepal early today at 1.57 am, was felt from Vadodara in the West to Siliguri in the East up to Vijayawada in the South, according to a preliminary report of the National Centre for Seismology (NCS), New Delhi.

The earthquake occurred at 01:57:24 IST near Dipayal Silgadhi, located in the District of Doti, Western Nepal. Its epicentre was 29.24º North and 81.06º East at a shallow focal depth of 10 km. The epicentre lay in western Nepal which is 85 Km SouthEast of Dharchula (Uttarakhand); 90 Km East-SouthEast of Pithoragarh (Uttarakhand); 140 Km NorthEast of Pilibhit (Uttarakhand); 150 Km East-SouthEast of Almorah (Uttarakhand); 260 Km North of Lucknow (U.P); 380 Km East-NorthEast of Delhi and 450 Km West-NorthWest of Kathmandu (Nepal).

The event was well recorded by 85 broadband seismic stations of the National Centre for Seismology.

The recorded earthquakes as per Earth Quake Catalogue of NCS reveals that the region is associated with moderate to large earthquakes with varying magnitude (M:2.0 and above) The following table shows the earthquakes of varying magnitude 5.0 and above that occurred between 1st Jan 2010 and 8th Nov 2022 in and around 200km of the present source zone.

In addition to the above, it is noteworthy that prior to the mainshock, there were two events prominently recorded on October 30, 2022, of Magnitude 4.1 and another Magnitude 4.9 earthquake that occurred in the rupture area of the present earthquake, and were felt with slight to moderate intensity.

This observation suggests that the source zone of November 9, 2022, has already started to release the accumulated strain energy. The occurrence of earthquakes in the region is attributed mainly to the tectonic settings of the Himalayas comprising Himalayan Frontal Thrust (HFT), Main Boundary Thrust (MBT) and Main Central Thrust (MCT) besides several local faults and geological demarcated lineaments. The neighbouring states of India that felt ground shaking falls under the seismic hazard zones IV and V. The source zone assimilated intensity was found to be varying between VIII and VII on the Modified Mercalli Intensity (MMI) scale, which gets reduced to Intensity between III and IV in NCR Delhi region.

– global bihari bureau