Depth, intensity of earthquakes in Türkiye made disaster more destructive: Experts

By Muhammed Enes Calli, Emre Basaran and Rabia Ali

ISTANBUL (AA) - Two major earthquakes in Türkiye did not only make headlines across the world but also drew attention from scientists who specialize in tectonic disasters.

Experts and scholars agree that the earthquakes were extremely powerful, with such large magnitude events occurring very rarely, and the buildings were not strong enough to withstand the shaking.

Türkiye, unfortunately, suffered very exceptional natural disasters and there are a number of scientific reasons why the earthquakes were very destructive.

According to Bill McGuire, a professor of geophysical and climate hazards at University College London, the earthquakes were so strong because there had not been a major one in the East Anatolian Fault Zone for a long time as there has not been such a massive earthquake for over 200 years.

"This allowed the fault to accumulate strain for a very long time, so its sudden release on Feb. 6 was able to generate a huge amount of energy and cause severe shaking. Another reason for the severity of the quakes is their shallow depths, which meant that much more of the seismic energy released reached the surface," McGuire told Anadolu.

Ian Main FRSE, a professor of Seismology and Rock Physics from the University of Edinburgh, said there were several factors that led to the massive destruction in Türkiye by the earthquakes.

"First, there are very large-magnitude events. This makes it harder to design buildings to withstand the strong shaking that results."

"Second, local site effects such as a thick layer of loose sediment may have amplified the ground motion under the foundations. This is particularly dangerous for high-rise buildings. Finally, the buildings themselves were also evidently highly vulnerable to such shaking," he told Anadolu.

A geologist from Pakistan, Dr. Sadaf Naseem, highlighted other factors that led to the extensive destruction in southern Türkiye: Intensity and depth.

"It was a shallow earthquake. It had a depth of 17 km, which was very shallow," said Naseem, who is also an assistant professor at the University of Karachi.

"Türkiye is already a tectonically active zone. The more energy is accumulated, the more shaking occurs. The more energy stored at shallow depth, the more destruction it causes."

"If it was a barren area, there would not have been so much loss of lives. But it was a heavily populated area, and there were multi-story buildings all around."

As of Friday morning, at least 18,000 people were killed and 74,000 others injured by two strong earthquakes that jolted southern Türkiye on Monday. The timing of the earthquake was early morning and while people were sleeping.

The magnitude 7.7 and 7.6 earthquakes, centered in the Kahramanmaras province, were felt by 13 million people across 10 provinces, including Adana, Adiyaman, Diyarbakir, Gaziantep, Hatay, Kilis, Malatya, Osmaniye, and Sanliurfa.

- Larger and stronger than tremblor of Aug. 1999

Dogan Kalafat, an associate professor at the Kandilli Observatory and Earthquake Research Institute at Istanbul's Bogazici University: "This is an earthquake larger and stronger than the Aug. 17 tremblor," referring to the Marmara earthquake that hit northwestern Türkiye on Aug. 17, 1999, killing more than 17,000 people."

"The acceleration compared to the Aug. 17 earthquake is four times bigger. It has acceleration values like twice the force of the Earth's gravity," Kalafat added.

Southern Türkiye was hit by a second earthquake less than 12 hours after the first one, which was triggered by the first disaster, according to Ian Main.

"The second would have happened at some point in the future. It just had its timing brought forward by the stress transferred and the ground shaking caused by the first."

- Energy released in earthquakes about 2,000 times size of atomic bomb dropped on Hiroshima

Bruce Malamud, a professor of Natural and Environmental Hazards from King's College London, pointed out by figures how the energy of the first earthquake was massive when it was compared to the size of the atomic bomb dropped on Japan's Hiroshima.

"The earthquake of magnitude 7.8 has a release of about 3 billion kilojoules, or the energy released in earthquakes about 2,000 times the size of the bomb dropped on Hiroshima," he told Anadolu.

"Another way to consider the energy is, by some estimates, this is the amount of electrical energy used by Turkey over 13 days."

Dr. Sadaf Naseem said that the geology of the area indicates that there is a high chance of further earthquakes striking the same area, as the region is seismically active.

"Mainly, Türkiye is on the Anatolian plate, having the Arabian plate at one end and the Eurasian plate at the other. Both plates are continuously squeezing the Anatolian plate, which is why Turkey has a history of high-intensity earthquakes."

Bill McGuir also agreed with Naseem about the possibility of earthquakes in the near future, adding that shaking in Türkiye's earthquakes was directly felt as far away as Egypt, Greece, and Russia.

"Seismic waves always travel through and around the planet, which is how a global system of seismometers can pinpoint the location of a quake," he added.

"There is particular interest in the quakes in California because the lateral (sideways) movement of the fault that generated the Turkey quakes is the same sort of movement that occurs on the San Andreas Fault. Here, too, a major earthquake is likely in coming decades," he added.