Are our cities and homes prepared for earthquakes?

The Himalayas were formed when two large tectonic plates collided - earthquakes occur when these plates shift. (Photo: Raimond Klavins via Unsplash)

New Year Day 2023, Sunday, Delhi NCR residents reported being woken up by an earthquake measuring 3.8 on the Richter Scale. On Thursday, January 5, 2023, another earthquake measuring 5.9 on the Richter Scale hit Afghanistan, again sending tremors to the Indian Capital.

In November 2022, north India was hit by a series of earthquakes, all within a span of 20-odd days. The strongest one, with a magnitude of 6.6 on the Richter scale, had its epicenter in Nepal and resulted in tremors which were felt across Delhi-NCR and neighbouring regions.

To be sure, if you live in north India, you're no stranger to earthquakes.

“The reason can be attributed to constant pressure of the Eurasian plate on the Indian plate, strained energy accumulating under it keeps releasing itself from time to time in the form of earthquakes”, news agency PTI quoted geophysicist Ajay Paul as saying.

Paul also predicted that a major earthquake might hit the Himalayan region soon. Paul claimed that the magnitude of the earthquake could be seven or more on the Richter scale.

Dr Jayalakshmi S., IIT Madras alumni and a PhD in Civil Engineering, explains: “Himalayas were formed as a result of the collision of Himalayan and Eurasian plates. The northernmost boundary of the Indian plate is still subducted beneath the Eurasian plate. When a major earthquake (of magnitude greater than 8) occurs, a huge amount of stress between the plates is released. This stress is redistributed and is often released in a series of earthquakes.”

Dr Jayalakshmi S, who is currently a professor at Mahindra University, says her objective is to predict earthquakes for seismic hazard assessment.

So, when can we expect the next big quake?

The short answer is: we don't have enough data to be able to predict exactly when the next big earthquake will hit. However, given what we know about why and how earthquakes occur, scientists can read patterns to suggest what might come next. In any event, it is a good idea to earmark seismic zones and reinforce infrastructure in these areas - especially old, decrepit structures that may not have been built to the strictest earthquake safety standards.

“In the early 2000s, a research paper by scientist and seismologist Roger Bilham quantified the magnitude of earthquake (the) Himalayan region can expect, which is greater than 8,” Dr Jayalakshmi says. “The historical data (however) is not enough for us to predict earthquakes," she adds.

"If one is asked to forecast an earthquake event, one would require statistics, which is unfortunately lacking in our literature. A time gap of 100 years can be expected between two major earthquakes,” Dr Jayalakshmi says.

Given the concerns around glacier bursts and flash floods in Uttarakhand and Himachal Pradesh, it is possible that earthquakes can trigger landslides too, says the geophysicist.

Safety checks

“As a country, we need to check our preparedness in case an earthquake strikes. The sedimentary base (soil) in north India is formed by the Ganges river. This makes it vulnerable to seismic amplification. To put it simply - the north Indian soil is likely to amplify earthquake waves,” says Dr Jayalakshmi. Meanwhile, southern India is likely to be safe from the earthquake since the distribution there is sporadic.

Dr Jayalakshmi adds: “Countries like Japan are always revisiting their area codes and revising the safety guidelines. Is it possible for us to expand our early warning systems? Is it possible to relook at our seismic zones? These are some questions we must ask ourselves”.

As far as structural reinforcements are concerned, Dr Jayalakshmi recommends using structural steel and bamboo reinforced concrete. “The material used should be ductile - it should be able to absorb the shock and withstand deformities. For hospitals and other important structures, one has to be more cautious.”

Another pressing question many ask is if their houses will survive a major earthquake. Dr Ratnakar Mahajan, a PhD in Civil Engineering and Technical Manager at engineering solutions company Maccaferri, says: “Over 50 percent of the Indian landmass is earthquake-prone. Having said that, Zones IV and V, which include places like Delhi and other north-eastern regions, are the zones in India that are most susceptible to earthquakes”.

“Most Indian homes, especially those in the north-eastern regions, are not newly developed constructions, making them particularly vulnerable to seismic events. The majority of recent residential construction projects will be resistant to small earthquakes, but the construction techniques and resources are much too outdated to endure tremors that are stronger than a 5 on the Richter scale.”

Elaborating on the same, the seismologist says: “This naturally raises concerns, given that the World Bank and United Nations anticipate that by 2050, almost 200 million Indian metropolitan inhabitants will be exposed to storms and earthquakes. So, in order to endure whatever may be in store for us in the future, I think that a planned infrastructure based on sustainable techniques is crucial in today's world.”

At the personal level, getting hard hats, torches, first-aid kit and emergency supplies for each member of the family doesn't take much time, investment, and effort - or even space to stow these away in a place you can access easily in case of an emergency.

Four major earthquakes were recorded in the Himalayan region over the past 150 years, including the tremors in Shillong in 1897, in Kangra in 1905, in Bihar-Nepal in 1934 and in Assam in 1950. Both experts maintain that nothing can be said about the frequency of the earthquakes.