The second biggest earthquake to hit Istanbul, after the Istanbul catastrophe in 1509, was on Thursday, May 22, 1766, when Ottoman Istanbul was hit by a massive earthquake, only second to the biggest ever earthquake that hit the city in 1509.

It shook Istanbul just half an hour after the sunrise and coincided with the third day of the Eid al-Adha, known as the Feast of Sacrifice. Following the tremor, its aftershocks continued for months.

Felt from Çorlu to Karamürsel

Nearly 4,000 people died and many more were injured in the aftermath of the quake. But the number was comparatively low because it coincided with Fajr, the morning prayers. However, the effects of this massive earthquake were felt over a large area, from İzmit to Tekirdağ to the southern parts of the Marmara Sea.

Provinces like Çorlu and Lüleburgaz were badly affected by the earthquake but the eastern part of Istanbul was hit the worst. Many villages and towns were damaged in the Gulf of İzmit along with some important buildings around Karamürsel. The Hersekzâde Ahmed Pasha Mosque and its kitchen in Dil Village (Hersek) lay in ruins. The second quake occurred on Aug. 5 the same year, causing more damage in these regions, and completely demolishing the wooden Court House in Karamürsel.

Buildings, especially around Istanbul's Yedikule and Edirnekapı districts were hard hit. The dome of the Fatih Mosque, which had already been affected by nearly every earthquake that hit Istanbul after its construction, collapsed. Its kitchen, hospital and madrasah were also destroyed. In total, some 173 mosques and public baths were damaged, including the Topkapı and Eski Palaces.

Parts of the city wall also collapsed and in the process damaged some nearby buildings, houses, shops, mills and inns. The Grand Bazaar and Örücüler Bazaar also suffered cracks and their vaults collapsed.

One of the footstalls of the Basilica Cistern broke down and the waterways of the city were badly damaged. The city's Çatalça, Büyükçekmece and Küçükçekmece districts also suffered and saw severe damage.

Life after the quake

After the earthquake, the biggest problem Istanbul residents faced was shelter. Although the damaged or wrecked houses were not the majority in Istanbul at the time, people who no longer had a roof over their heads needed immediate shelter and once they got it, they had to live in tents for a long time before finding or building a new home for themselves.

The successive earthquakes that continued over some eight months, as well as a massive one on Aug. 5, prevented people from returning to their houses. Luckily, it was summer, which made it easy for people to stay outdoors.

Along with the houses, inns for single people and passengers were also demolished, making these people practically homeless. The mental state of Istanbul residents was in tatters, living under constant fear evoked by the continuous tremors.

The earthquake also affected the city's supply of food and drinking water. The water supply network was in bad shape and this made it very difficult for people to find drinking water easily. In addition, the demolished bakeries, mills, food stores and inns caused a city-wide food shortage. To make matters worse, the cities barley stocks were also depleted.

Because the network of roads also lay in ruins, transporting food and water also became difficult. Some areas near the city walls were closed to access because they destroyed some of the city's waterways. Shelters for domesticated animals became another issue and most were left to stay outside like people.

Istanbul has always been at risk

Although Istanbul is a first-degree seismic zone, the earthquakes that occurred here throughout history are not known in detail by many people. Measurement using modern equipment has been done for nearly a century but detailed information about property damage, loss of life, its effect on the economy, social life and human relations, as well as reconstruction efforts, remain scarce.

The information on Istanbul's earthquakes in historical texts should be researched and presented for the use of experts, local executives, urban planners, architects, and historians.

Earthquake experts say that quakes in Istanbul occur in a 250-year cycle, and its last massive quake was in 1766. However, we know little about the relations between Istanbul's earthquakes in 1556, 1690, 1719, 1754 and 1894, as there has been little research on the historical earthquakes. We do not know which fault line moved in which particular incident and it is hard to know or predict whether the city will be hit by one in the near future and if it is hit, which parts of it will be the worst affected.

Istanbul earthquakes in Ottoman Era

In Ottoman Istanbul, the second largest earthquake occurred on the night of May 10, 1556. This was the first earthquake in the city in more than 90 years. On June 28, 1648, people in Istanbul and İzmit woke up to the grounds shaking at the dawn. However, this earthquake didn't cause much trouble or damage. On July 11, 1690, a quake shook Istanbul again. It wasn't really massive and damage was also limited.

The earthquake on May 25, 1719, which occurred early in the morning, was so massive that it caused damage all the way to İzmit. Another quake on July 30, 1752, affected not only the region but also Bulgaria. And after just two years, another earthquake hit Istanbul on Sept. 2, 1754. It was not as strong as the previous ones and the damage in the city was not extensive.

After the 1766 earthquake, Istanbul wasn't hit by tremor for a long time until on July 10, 1894. This one affected a large area in Istanbul to Yalova.

The was another one near Şarköy-Mürefte on Aug. 9, 1912. It was recorded as a 7.3 magnitude earthquake, which caused severe damage in the south of Edirne.