Authorities are rushing to move hundreds of thousands of homeless people from tents to container cities.

Interior Minister Suleyman Soylu said 564 suspects had been identified, with 160 people arrested and many more still under investigation for their role in the collapse of some of the thousands of buildings flattened in the 10 provinces affected by the earthquakes.

Opposition parties have accused President Recep Tayyip Erdogan’s government of not enforcing building regulations, and of misspending special taxes levied after the last major earthquake in 1999 to make buildings more resistant to quakes.

The death toll from the quakes that devastated the Turkey-Syria border region has risen to nearly 50,000, with close to 8,000 aftershocks recorded. Soylu said 43,556 people have died in Turkey.

Reporting from the southern Turkish city of Adana, Al Jazeera’s Sami Zeidan said, citing the United Nations, that 1.5 million people became homeless by the earthquakes. Some 500,000 homes have been destroyed and 210 million tonnes of rubble need to be cleared, which would fill an area of 30sq km (11.6sq miles).

Turkey started an operation on Thursday to relocate people from tents to container cities. The first phase would be to move people into 15,000 containers.

Erdogan, who faces elections within months, has promised to rebuild housing within one year.

This week he said about 865,000 people were living in tents and 23,500 in container homes, while 376,000 were in student dormitories and public guesthouses outside the earthquake zone.

High anxiety in Istanbul

There have always been fears of the next big earthquake in Istanbul, Turkey’s most populous city. But now there is a greater sense of urgency among residents who want experts to certify that their buildings are strong and the foundations robust, said Al Jazeera’s Hashem Ahelbarra.

Building inspectors have been scanning for cracks or poor foundations to identify the structures that need to be demolished or repaired. City officials recently warned that 90,000 buildings could collapse if a strong quake hits Istanbul.

“An earthquake in Istanbul will affect 4.5 million people,” said Burga Gokce from the Istanbul Municipality. “This is a top priority for us and should be seen as a national security matter.”

Levant Aktas, who bought his home three years ago, is among a growing number of people who no longer feel safe in Istanbul.

“I’m not planning to stay longer in Istanbul. Eventually, I will have to leave for another place. I’m thinking about taking my family to a safer city,” Aktas said.