Hyderabad: Wednesday’s quake occurred in the Godavari basin, which has many geological faults and falls and has experienced minor to moderate earthquakes in the past, said Dr Prakash Kumar, Director, National Geographical Research Institute (NGRI).
The Telangana region has had previous earthquakes of around 4 or 5 magnitude and the one on Wednesday was part of the cyclic activity, which refers to the repetitive pattern of the earthquakes in a region.
"The last one occurred in 1969 in Bhdrachalam, which was 5.7 on Richter scale. The more recent ones include 4.8 in Medchal and 4.6 in Pulichintala in 2021," said Dr Kumar.
India has four seismic zones, he explained. The Deccan plateau region falls in zone III, where earthquakes going up to magnitude 6 can occur.
According to Dr N. Purnachandra Rao, former chief scientist, NGRI. and former director National Centre for Earth Science Studies, Kochi, Wednesday’ s event could be termed as a return period quake (after the 1969 quake), something that was expected to occur.
The time gap between large quakes of this nature is long, but there are several smaller magnitude earthquakes that occur regularly, including magnitude 3 tremblors.
"The impact from a 5.3 magnitude quake does not typically result in severe damage to structures like buildings collapsing, or deaths of people, but there will be ground shakes as experienced by people, and walls may develop cracks, but this last aspect depends on the construction quality too," Dr Rao stated. Also, quakes occurring deep in the ground cause less damage.
"The frequency of the quakes is inversely proportional to the magnitude. A larger earthquake occurs less frequently and after a long time in the same region and vice-versa. Another quake like Wednesday one may not happen for a few more decades," Dr Rao said.
"Wednesday’s quake happened in the Godavari rift valley, which has many faults. Whenever there is a little extra stress, there can be quakes as the faults slip and slide, releasing the stress. This is the reason why we experienced quakes all along Godavari river, at Bhadrachalam, Warangal, Khammam, and so on in the past," Dr Rao explained.
Explaining how faults occur along a river, Dr Rao, said, " The course of the river today may not be the same as it was a few hundred years ago. River courses change and as they change they leave their mark on the earth structure. Hidden courses of the past, faults can be anywhere, extending to several km on both sides of a river."
He also highlighted that the grinding of the Indian plate into the Eurasian plate does not result in quakes just in the north, along the Himayalas, but the stress of this tectonic movement also builds in the rest of the Indian plate. Sometimes these stresses may manifest as quakes and are called intra-plate quakes.
How to save yourself
Before
Prepare emergency Kit: Include essentials such as water, non-perishable food, first-aid supplies, flashlights, batteries, and important documents.
Identify safe spots: Learn safe places in your home, such as under sturdy furniture or against an interior wall, away from windows and heavy objects.
Plan evacuation route: Ensure all family members know the safest way out of the building.
Secure heavy items: Fasten bookshelves, mirrors, and other heavy objects to walls to prevent them from falling.
During
Drop, cover, and hold on:
Drop to your hands and knees to avoid being knocked down.
Cover your head and neck with your arms and, if possible, get under a sturdy table or piece of furniture.
Hold on until the shaking stops.
Stay Indoors: Do not run outside as debris may fall, causing injury.
Avoid dangerous areas: Stay away from windows, glass, mirrors, and heavy furniture that could topple.
If outdoors: Move to an open area away from buildings, trees, streetlights, and utility wires.
If driving: Stop safely, stay in the vehicle, and avoid stopping under bridges, overpasses, or near tall structures.
After
Check for Injuries: Administer first aid if necessary and seek medical attention for serious injuries.
Inspect for damage: Avoid using damaged buildings or infrastructure until declared safe by authorities.
Avoid open flames: Do not light matches or candles, as gas leaks could cause explosions.
Follow official updates: Stay tuned to local news or alerts for information on aftershocks and emergency instructions.
Be prepared for Aftershocks: These may follow the main quake and cause additional damage.
Information provided by S.P. Anchuri, structural engineer.
Richter Scale
Formulated by Charles F. Richter and Beno Gutenburg in 1935, it measures energy waves created by earthquakes. Grade ranges from 0 to 9 or over, with 9 and more being the most devastating;
0-1.9: Can be detected only by seismographs – devices that measure the quakes and plot them on paper as the events occur;
2-2.9: Can cause hanging objects to swing;
3-3.9: Feel like vibrations of the passing of a heavy lorry;
4-4.9: Glass windows may break, cause small or unstable unsecured objects to fall off shelves;
5-5.9: Furniture in the house can move, can cause plaster to fall from walls;
6-6.9: Can damage well built structures, can cause severe damage to poorly built ones;
7-7.9: Buildings can get displaced from their foundations, cracks can appear on earth surface, underground pipes can break;
8-8.9: Few structures are left standing, bridges downed;
9 and above: Near total destruction, earthquake waves visible to the eye with earth surface heaving
Tectonic movement
The surface of the earth, both visible and underwater, is comprised of several ‘plates’ – very large chunks of the planet’s surface that move extremely slowly.
India, as a country sits on one such plate, the Indian Plate, which is moving northwards and pushing into the Eurasian Plate.
This movement is what created the Himalayan mountain range.
Though most of the stress along the line of collision between these two plates results in strong to severe earthquakes along this fault line, the stress from the grinding can build up extremely slowly in other parts of the Indian plate along various other geological faults which too come under stress and strain.
Their ‘adjustments’ can result in quakes.
