Sunday, 26 March, 2023

The Tremor before Dawn

A K Ziauddin Ahmed

The Tremor before Dawn

The Turkey-Syria earthquake death toll has now surpassed 46,000. And it is rather certain that the number will go up further. More bodies will be recovered from the rubbles of thousands of buildings. These were the people who had plans, hopes, and dreams for the future. They went to bed on the night of February 5. It was Sunday. The next day would be a working day. But they never woke up. The earthquake struck before dawn at 4:17 am on February 6, 2023. The survivors stood on the dark streets in the freezing cold – dazed, bewildered. They did not know yet what happened to their family members who were not there. They did not realise yet that they had just become homeless and destitute.

The earthquake measured 7.8 on the Richter scale with an aftershock of magnitude 7.5. Earthquakes from 7.0 to 7.9 magnitude are categorised as major earthquakes. Magnitudes 8.0 and higher are great earthquakes. A 9.1 magnitude undersea earthquake struck Indonesia in 2004 triggering a massive tsunami that hit not only the coastlines of Indonesia but also Thailand, India, Sri Lanka and the Maldives. The total number of deaths recorded was 227,898. The largest-ever earthquake was of 9.5 magnitude that occurred off the coast of Chile in 1960. It also produced a tsunami that caused destruction in Chile and the faraway coastlines of Hawaii, Japan, and the Philippines. There were different estimates of the total number of fatalities ranging from 2,231 to 6,000. The devastation and death toll does not depend solely on the strength of the quake but also on the conditions of structures, infrastructures, population density, etc. in the area.

But why did the earthquake hit Turkey and Syria? Why do they happen at all? To find the answer, we have to delve a little into the mechanics of earthquakes.

The matter inside the Earth is arranged in several layers. The outer layer is called the crust. The crust is broken into pieces called tectonic plates. The boundary line between two plates is called the fault line. The layer below the crust is the mantle which is a kind of soft solid. So, the tectonic plates can be imagined as somewhat ‘floating’ on the mantle. And as they move, there are crashes, frictions, or pulling apart along the fault lines which cause earthquakes. Many organisations around the world are mapping these fault lines and a non-profit public-private partnership initiated by OECD’s Global Science Forum named, Global Earthquake Model Foundation (GEM), is compiling them into a single database. From GEM’s global active fault map, it can be seen that there is a huge concentration of fault lines along a belt from Italy through Greece, Turkey, Iran, Afghanistan, the Himalayas to Myanmar. GEM’s seismic hazard map clearly shows the vulnerability of Turkey to earthquakes.

Indeed, Turkey has a history of earthquakes. In 526 AD, an earthquake completely destroyed the city of Antioch, present-day Antakya, with an estimated death toll of 250,000. In 1268, an earthquake in ancient Cilicia, the northeast of the present-day city of Adana killed over 60,000 people. Major earthquakes killing over 10,000 people occurred in 1509, 1688, 1784, 1840, and 1859. In more recent times, over 32,000 people died in the Erzincan earthquake in 1939 and over 17,000 people were killed in the Izmit earthquake in 1999.

With such a history of earthquakes and a known level of vulnerability, Turkey must have had preparations and systems in place for minimising the loss of lives and damages. But Constanze Letsch, an award-winning journalist, contends it in her article published in the Guardian on February 15, 2023. Letsch observes that the government of Turkey focused on massive infrastructure and construction projects as the main motor of economic growth and turned a blind eye to irregularities in construction and violations of safety standards. In 2018, the environment and urbanisation ministry itself declared that more than half of the buildings in Turkey, which means around 13 million buildings, violated construction and safety regulations. Turkey has now issued arrest warrants against some 134 people related to the construction of buildings that collapsed in the earthquake. They were supposedly involved in shoddy and illegal construction methods.

As we have noted above, factors like conditions of structures, infrastructures and population density have strong impacts on the devastation and death toll in an earthquake. Dhaka has the highest population density among all the cities in the world. Also, according to a research paper titled, ‘Earthquake Catalogue of Bangladesh’ published in the International Journal of Science, Environment and Technology in 2018, the authors cited that Bangladesh has been affected by earthquake disasters since ancient times and Dhaka was the epicentre of earthquakes in 1664, 1828, 1852, and 1885. In another journal article titled, ‘Earthquake Risks in Bangladesh: Causes, Vulnerability, Preparedness and Strategies for Mitigation’ published in the ARPN Journal of Earth Sciences in 2016, the authors mentioned that five fault lines have run through Bangladesh.

GEM’s Global Seismic Hazard Map shows that the Peak Ground Acceleration (PGA) for Bangladesh ranges from 0.11 to 0.47. PGA 0.11 is in Chuadanga-Meherpur area and 0.47 is in Sylhet. To understand the effect of these PGA values we can correlate them with the Modified Mercalli Intensity Scale (MMI). MMI measures how the earth’s shaking during an earthquake is felt by people and the consequent levels of possible damage. It has 12 levels. Many researchers have developed relationships between Richter’s magnitude and MMI, and between MMI and PGA. Following one such relationship between MMI and PGA provided by the University of the West Indies Seismic Research Centre, we can interpret the PGA range for Bangladesh shown in GEM’s Global Seismic Hazard Map. PGA 0.11 corresponds to level 8 of MMI which means very strong shaking of the ground that may cause partial collapse of buildings. PGA 0.47 corresponds to level 9 of MMI which means violent shaking of the ground, general panic, and heavy damage or collapse of buildings.

The Turkish tragedy is still unfolding in front of our eyes. We need to be alert; we need to reckon.


The writer is a former Corporate Professional and Academic