The city lies on the northern edge of one of Türkiye's main fault lines and is densely packed.
A 7.6-magnitude earthquake with an epicentre on the city's eastern outskirts killed more than 17,000 people in 1999.
The number of Istanbulites has roughly doubled since then.
Independent urban scholar Murat Güney said Istanbul had an ample supply of vacant properties just recently constructed and strong enough to withstand major jolts.
The February 6 earthquake claimed the lives of more than 38,000 people in southeastern Türkiye and nearly 3,700 in neighbouring Syria.
Officials say more than 55,000 buildings were either levelled or damaged beyond repair.
Its impact was felt across a part of Türkiye with approximately the same population as Istanbul.
The quake affected more than 13 million people across 11 provinces, including Adana, Adıyaman, Diyarbakır, Gaziantep, Hatay, Kilis, Malatya, Osmaniye, Şanlıurfa, and Elazığ.
