US seismologists weigh in on what made Türkiye earthquakes deadly

Deadly earthquakes in southern Türkiye, which hit 10 provinces on Monday, were quite severe due to their close proximity to the surface and the type of fault, US seismologists have said.

The Eastern Anatolian Fault is a "strike-slip" vertical fault, very similar to the well-known San Andreas Fault in California, seismologist Lucy Jones, also known as "the earthquake lady", told the Anadolu Agency.

"That means the shaking is being released very, very close to people right up close to the Earth's surface. And it means that people are located much closer to the source of the shaking than in many other types of earthquakes. And therefore right along the fault, you can see really extremely high levels of shaking," she said.

Jones said Monday’s second major earthquake, which measured magnitude 7.6 and came hours after the first, at magnitude 7.7, was not unusual, adding the aftershocks in similar situations can be larger than the main shock and is part of the same distribution 

"It really is the way these big faults move."

On the lack of depth of the first quake, she said: "It began at a depth of about 17 kilometres, but it ruptured up towards the surface. So you don't really think of it as being at 17 kilometres .... This is considered a shallow earthquake."

‘Turkey follows same building code as California'

She said 7.8 magnitude earthquakes typically happen worldwide once or twice a year, but they usually take place in deep layers or in remote areas where they affect few people.

Underlining that people living close to major fault lines can cause great destruction in earthquakes, she added: "Turkey follows the International Building Code just like California does, and has excellent engineers. I've worked with them here in the United States. They're very much an integral part of the international earthquake engineering community.

"So it's not that Turkey has different codes or different engineers than we do here in the United States. However, having a great design doesn't mean you have a great building. There's several reasons that the buildings might not be what you want it to be."

She said the earthquakes in Kahramanmaras may have a very low risk of causing severe earthquakes along other fault lines.

Referring to the earthquakes and the aftershocks that killed more than 12,000 and affected over 13 million people in the region, Clark Alexander, director of the University of Georgia's Skidaway Institute of Oceanography, said: "If you compare it to other earthquakes in other places around the globe, it is large, but it's certainly not unique in its magnitude."

On Türkiye's East Anatolian Fault, Alexander said: "These tectonic forces have been active for millions of years. And so these fault systems have existed and have probably been producing earthquakes over those same kinds of time periods."