What lessons should Northeast India take from Turkey-Syria earthquake?

Guwahati, March 27: The back-to-back massive earthquakes that struck southern and central Turkey and northern and western Syria has resulted in widespread damage to life and property in both the countries. The “major” quakes and its aftershocks has flattened buildings and compelled rescuers to dig deeper to find survivors. The bolt from the blue on February 6, 2023 has traumatised people in Turkey and war-torn Syria. Meanwhile, the Northeastern region of India which is considered to be seismically one of the six most active regions of the world has been experiencing frequent earthquakes raising concern among the people over the vulnerability of Northeast to a medium or high intensity quake.

What causes an earthquake?

The earth’s crust is made up of several tectonic plates that are nestled with each other. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When pressure builds up on the edge, there is an earthquake that releases energy in waves and travel through the earth's crust and cause the shaking that we feel. According to reports, the seismic event that hit Turkey and Syria was due to the collision between the Arabian plate moving northwards and grinding against the Anatolian plate.

Why it was the deadliest?

Turkey is no stranger to strong earthquakes as it falls under the seismically active zone. Seven quakes with magnitude 7.0 or greater have struck the country in the past 25 years. However, the recent one (7.8) was a ‘major’ one. Experts figured out that the massive destruction struck at the wee hours, when most of the people were sleeping and were trapped under the rubble of their homes. Moreover, the buildings, especially the older ones lacked sturdiness as it was not built in accordance to the modern Turkish seismic standard, making it vulnerable to the severity of the shocks. According to reports, more than 160,000 buildings containing 520,000 apartments collapsed or were severely damaged in the disaster.

The deadly earthquake apart from causing physical destruction and decline in economic activity in war-torn Syria, has only added to years of destruction, suffering and hardship the people have been enduring over the past years due to the civil war.

Northeast Indian and earthquakes:

Over the past three months the North-eastern region of India has experienced over 30 low-intensity earthquakes as per the National Seismological Centre. In January the intensity of the earthquake was between 2.9 to 4.8 with a total of 7 earthquakes.

In February, the region experienced 16 quakes and the intensity was from 2.5 to 4.0 on the Richter scale.

Meanwhile, in March this year over 10 earthquakes jolted northeast between magnitude 2.7 to 3.9 till the filing of this report.

Earlier in 2020, Mizoram experienced several earthquakes of light intensity compelling people to stay outdoors. The situation spooked the residents as they spent sleepless nights and the matter reached the parliament after Rajya Sabha MP from Mizoram K Vanlalvena urged the Centre to give compensations to people affected by earthquakes in Mizoram and to send a team to investigate the cause of frequent earthquakes in the state.

It’s not that Northeast did not face any high-intensity earthquake, the Great Assam Earthquake of 1897 with an estimated magnitude of 8.2-8.3 on the Richter scale, the 1943 earthquake (7.3 magnitude), 1950 Assam-Tibet earthquake (8.6 magnitude) are a few cases in point. These quakes have somehow changed the topography of the region which is surrounded by red rivers and blue hills. The frequent and low intensity quakes have raised concerns among the people if this is an underlying warning of something big coming up.

Professor Bhagawat Pran Duarah from the Department of Geological Sciences, Gauhati University explained that the North-eastern part of India exists in the zone of interaction of three tectonic plates – the Indian, Tibetan and Burmese. The Indian plate is continuously going down the Tibetan and the Burmese plates due to its journey towards north-east direction.

“The compressive phenomena accumulate lot of energy in the zone of collision which goes on adding continuously and thus stress on the earth’s crust becomes reasonably tremendous and is sufficient to break and slip a portion of the earth crust. The slip generates earthquake; longer break, and larger and faster slip generates larger earthquake. All these elements that exist in the Northeast make it vulnerable to earthquakes,” Duarah added.

On being asked about the frequent, low-intensity quakes, Duarah said that Northeast being a seismically active zone with many active fault lines it is natural to witness frequent earthquakes. “Usually, a small part of the accumulated strain energy is released by small earthquakes, though most of the energy remains in store of the earth's crust. This may postpone the time of occurrence of a large earthquake and the potential of occurrence of a large earthquake is to be eliminated.”

Urbanisation and seismic risk:

Over the years there has been phenomenal increase in population density and the region has witnessed mushrooming of high rises and unplanned urban centres. This has increased the vulnerability of human population and physical structures to the earthquakes. Duarah stressed that unplanned activities in urban areas, poor design of buildings / houses, narrow roads, compact colony, soil type on which the urban area is located need to be assessed properly and also need to create awareness among the residents. “Participatory actions are always fruitful, and the government regulations and laws alone cannot reduce vulnerability,” added Duarah.

Lessons from Turkey-Syria quake

Northeast India is seismically one of the six most active regions of the world, the other five being Mexico, Taiwan, California, Japan and Turkey. Following the devastating earthquake that jolted Turkey and Syria border, Professor Duarah asserted that the last earthquake that rocked the northeast was the 1950’s (8.5 magnitude) quake. The loss of life in the earthquake was less (1500 deaths) as compared to the recent Turkey earthquake (about 40,000 deaths). “The present physical structure, population density and human activity are witnessing dramatic changes since the 1950’s. So, it may not, perhaps, be impractical to expect a more damaging scenario for an earthquake of similar magnitude at present day. Fortunately, people and governments of Northeast India are aware about earthquake vulnerability and are careful and build good physical structure. However, there is scope to assess the old buildings and houses for seismic adequacy,” Duarah added.

Professor Duarah further highlighted that the scientific knowledge on seismic behaviours and response of the North-eastern terrain needs to be developed. A large network of seismic instrumentation and study of historical and paleo-earthquakes in the region to understand the crust and crustal materials response to eearthquakesis indispensable so that proper planning can be made to mitigate earthquake hazards.