An extremely large earthquake has occurred in the southeast of Türkiye, near the border with Syria.
Data from seismometers measuring ground tremors caused by earthquake waves suggest that this event was of magnitude 7.8 out of 10 on the Moment Magnitude Scale.
Seismic waves have been detected by sensors around the world (you can watch them waves through Europe) including places as far away as the UK.
This was a really big deal.
The shaking caused by energy traveling outward from the source or epicenter is already wreaking havoc on those living nearby.
Many buildings have collapsed at least 2,000 people They are believed to have died in both countries and there have been reports of gas pipeline damage leading to fires.
Why this happened here
This area of Türkiye is prone to earthquakes as it lies at the intersection of three of the tectonic plates that make up the Earth’s crust: the Anatolian, Arabian and African plates. Arabia moves north into Europe, causing the Anatolian Plate (on which Türkiye sits) to shift west.
The movement of the tectonic plates builds pressure on fault zones at their boundaries. It is the sudden release of this pressure that causes earthquakes and ground shaking.
This latest earthquake probably occurred on one of the largest faults that mark the boundaries between the Anatolian and Arabian plates: either the East Anatolian Fault or Dead Sea Fault.
These are both “strike slip errors”, meaning they pick up some movement from plates moving past each other.
“Significantly larger” than previous earthquakes
While there are many earthquakes in this area each year caused by the continued movement of the tectonic plates, today’s earthquake is particularly large and devastating because so much energy was released.
The United States Geological Survey (USGS) reports that only three earthquakes greater than magnitude 6 have occurred within a 250-kilometer (155-mile) radius of this location since 1970.
With a magnitude of 7.8, the Feb. 6 event is significantly larger than those the area has experienced before and released more than twice the energy of the largest previously recorded earthquake in the region (size 7.4).
The finite fault model is beginning to take shape, indicating the fault segment that has been moving in the present day #Earthquake There is still a lot of work to be done on this. pic.twitter.com/UhxBNXwUtY
– dr Susan Hough 🦖 (@SeismoSue) February 6, 2023
Modern seismologists use the Moment Magnitude Scalewhich represents the amount of energy released in an earthquake (the Richter scale is outdated but sometimes misquoted in the news).
This scale is not linear: each step up corresponds to 32 times more energy released. This means that a strength of 7.8 is actually released 6,000 times more energy than the more moderate magnitude 5 earthquakes that can normally occur in the region.
We tend to think of earthquake energy as coming from a single location or epicenter, but they are actually caused by movement along a fault area. The stronger the earthquake, the larger the fault plane that will have shifted.
For something as large as this magnitude 7.8, there should have been movement over an area about 120 miles long and 15 miles wide. This means that the shaking can be felt over a very large area.
Strong to violent shaking (enough to cause significant property damage) is estimated to have been felt by 610,000 people inland to about 80 kilometers northeast along the tectonic plate boundary.
Slight shaking was felt in the Turkish capital Istanbul (around 815 kilometers away) as well as Baghdad in Iraq (800 kilometers) and Cairo in Egypt (950 kilometers).
What about aftershocks?
After large earthquakes, there will be many smaller earthquakes, known as aftershocks, as the crust adjusts to the changes in loading. These can last days to years after the initial event.
In the first 12 hours after the first quake in the south-east of Türkiye there were already three more earthquakes above magnitude 6.0. The first was a 6.7 that occurred just 11 minutes after the initial shock and there were hundreds of lower magnitude aftershocks.
Later in the morning, another very large magnitude 7.5 occurred further north on a different but adjacent fault system: the Sürgü Fault.
Technically, this earthquake was strong enough to be considered an earthquake in its own right, although it was likely triggered by the first earthquake and will trigger its own series of aftershocks.
While aftershocks are typically significantly smaller than the main tremor, they can be equally devastating, further damaging infrastructure damaged by the initial earthquake and hampering rescue efforts.
As people in this region continue to feel the aftermath of this major earthquake, we can only hope that international aid will reach Türkiye and Syria as soon as possible to help with ongoing rescue efforts amid the ongoing aftershocks.
JennyJenkinsAssistant Professor, Department of Earth Sciences, University of Durham
This article is republished by The conversation under a Creative Commons license. read this original article.
