- Pallab Ghosh
- technology reporter
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In the early hours of Monday (February 6), a powerful earthquake struck southeastern Turkey near the Syrian border, killing more than 20,000 people and injuring many others.
The quake, which struck near the town of Gaziantep, was followed by several aftershocks, one of which was nearly as powerful as the first quake.
Why is it so deadly?
The first quake was so strong it was recorded as a magnitude 7.8, which is listed as “significant” on the official scale. The quake ruptured about 100 kilometers along the fault line, causing severe damage to buildings near the fault.
Professor Joanna Faure Walker, director of the Institute of Risk and Disaster Mitigation at University College London, said: “Among the deadliest earthquakes in any given year, there have only been two of comparable magnitude in the past 10 years, and four in the previous decade.”
But it wasn’t just the power of the earthquake that caused the damage.
The incident happened in the early hours of the morning when people were sleeping indoors.
The sturdiness of the building is also a factor.
Dr Carmen Solana, associate professor of volcanology and risk communication at the University of Portsmouth in the UK, said: “Unfortunately, in southern Turkey, especially in Syria, the defense infrastructure is not well developed, so saving lives is now largely dependent on earthquakes. Post-response measures. The first 24 hours after an earthquake are critical to finding survivors. After 48 hours, the number of survivors is significantly reduced.”
It’s a region that hasn’t had a major earthquake or any warning sign in more than 200 years, so the level of preparedness is lower than in a region more used to dealing with earthquakes.
What caused an earthquake?
The Earth’s crust is made up of separate plates that are held together.
These plates often try to move but are unable to due to friction with adjacent plates. But sometimes the pressure builds until a plate shifts suddenly, causing the surface to shift.
Specifically, this earthquake was caused by the northward movement of the Arabian plate and the collision with the Anatolian plate.
In the past, friction between plates has led to extremely destructive earthquakes.
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That friction triggered a 7.4-magnitude earthquake here on Aug. 13, 1822, down from the 7.8 recorded on Monday.
Even so, earthquakes in the 19th century wreaked havoc on towns and cities in the region, killing 7,000 people in the city of Aleppo alone. Destructive aftershocks persisted for nearly a year.
The quake has been followed by several aftershocks, and scientists expect the quake to follow the trend of the last major quake in the region.
How are earthquakes measured?
They are measured using a scale called moment magnitude (Mw). It replaced the better known Richter scale, which is now considered outdated and less accurate.
The number of earthquakes is a combination of the distance the fault line moved and the force that moved it.
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Shocks of magnitude 2.5 or less are usually not felt, but can be detected by instruments. Earthquakes up to magnitude 5 can be felt and cause minor damage. A 7.8-magnitude quake like the one in Turkey is classified as a major earthquake and usually causes severe damage.
Any tremor above 8 would be catastrophic and could completely wipe out communities at the epicenter.
How does the magnitude of this earthquake compare to other large earthquakes?
On December 26, 2004, one of the largest earthquakes ever recorded hit the coast of Indonesia, triggering a tsunami that engulfed entire communities around the Indian Ocean. The 9.1-magnitude quake killed about 228,000 people.
Another magnitude 9 earthquake off the coast of Japan in 2011 caused widespread damage on land and triggered a tsunami. This led to a major accident at the Fukushima nuclear power plant off the coast.
In 1960, Chile was hit by the largest magnitude 9.5 earthquake ever recorded.