Here's what we know about what caused the Turkey earthquake

The region of Turkey and Syria hit by Monday's 7.8-magnitude earthquake is the strongest in its seismic zone and is known for experiencing large earthquakes, but has not been seen for decades. More than 5,000 people died in the area. Here's a look at what happened, in terms of geography, and why it caused so much damage. Earthquakes are common in Turkey and Syria

The Arabian Peninsula is part of a tectonic plate moving north into the Eurasian Plate, and the entire country of Turkey is being subducted.Arabia is slowly moving north and fighting Turkey, Turkey is moving west," says Michael Steckler of the Lamont-Doherty Earth Observatory at Columbia University.This tectonic shift has been causing earthquakes for thousands of years in the region, including one that shook the Syrian city of Aleppo in 1138. Other recent earthquakes, such as the 1999 earthquake that hit the city of 'Izmit, killed thousands of people.Monday's earthquake is considered the strongest Turkey has experienced in more than 80 years.

This particular region was overdue for a big one

Many of the largest earthquakes of the last century occurred along the North Anatolian fault. But stress has been building on another major fault: the Eastern Anatolia Fault. Patricia Martínez-Garzón, a seismologist at GFZ Potsdam, a research institute in Germany, said: But recently, there hasn't been much work. Some researchers have begun to think that the cause is due to a large earthquake, according to Fatih Bulut of the Kandilli Observatory and Earthquake Research Center at Boğaziçi University in Istanbul. His team of researchers and others have used computer models to show that this fault could have earthquakes of magnitude 7.4 or greater. "It's not a surprise to us," Bulut told NPR.

But that doesn't mean seismologists can predict exactly when a big one will hit, said Ian Main, a seismologist at the University of Edinburgh in the UK. The time between a major earthquake and a fault can vary unpredictably, he says. "It's not like cars, they don't follow a schedule."

But not all jolts happened in this one spot. The first earthquake hit the Dead Sea transform, another fault zone where the Arabian, Anatolian and African plates converge. But a second earthquake of 7.5 occurred a few hours later due to a nearby fault that was placed but is not part of the East Anatolian fault. It's a busy and complicated area with many fault systems," says Steckler.

This was a "strike-slip" earthquake

The earthquake happened because "two pieces of the earth are crossing each other horizontally," Steckler explains. This is one type of earthquake that occurs along the San Andreas Fault in California. This movement also means that the tremors extend for several kilometers due to the fault, Bulut explained. He says the area affected "is very large." \"Ten countries have been structurally affected in Turkey.''

Turkey has seismic codes to try to prevent buildings from collapsing, but Bulut says that because this region has avoided earthquakes for decades, some old buildings may be vulnerable. "Sometimes there are old things that were built before the law," he says. Steckler says he suspects even some new buildings may not be up to code. "I know that of course in Istanbul there are many illegal constructions," he says.

More aftershocks are likely

The US Geological Survey has already documented more than 100 landslides in the area, and experts expect them to continue for some time. Steckler says, "Throughout this phase, all parts of the world will slowly move, break and break and achieve a new balance. Earthquake surface waves are like ocean waves — even long after you drop a stone in a body of water to create a disturbance, the waves propagate outward. The same is true with an earthquake.