İstanbul: A brief seismic history

A rather fanciful European engraving of an earthquake that took place in İstanbul on May 10th 1556. (For an enlarged view of the image, click on it.) People are running about in terror and the sea is surging violently. Notice the comet at the top center and the impending or recent eclipse of the sun or moon at the right. Right of center is a large domed structure that may be intended to represent Hagia Sophia.

At 3:02 a.m. August 17th 1999, İstanbul experienced yet another of the violent earthquakes from which the city appears to have suffered roughly once a century throughout recorded history. The lesson that history should teach us is that İstanbul, located near but not on the Northern Anatolian fault line, can expect to be severely shaken about once every hundred years by a major earthquake that takes place in the vicinity while suffering from lesser shocks about once a decade or so in between. İstanbul has never suffered from a "killer" earthquake--one that completely laid the city waste. Monuments such as the Theodosian Walls, Hagia Sophia, and the Suleymaniye and Sultan Ahmet mosques are proof enough of that. But the big quakes can cause considerable loss of life and property in structures that have not been built to withstand tremors. The earthquake that struck in the early morning hours of August 17th was one of those.

The first known earthquake serious enough to be mentioned in sources from the Ottoman period (1453-1923) took place in 1489 and it is said to have caused some damage in the city. (Note: Not all of the earthquakes mentioned in Ottoman sources appear in the NEIC chart and the chart includes earthquakes that are not mentioned in Ottoman sources–possibly because of their distance or direction from the city they were not felt there.) The earthquake of 1509 was a particularly strong one and contemporary accounts refer to it as "The Lesser Judgement Day". The aftershocks from that earthquake continued for forty-five days. A hundred nine mosques and more than a thousand dwellings were destroyed. The death toll, which is believed to have numbered around ten thousand, was worsened as huge waves rushing in from the Marmara sea and crashing over the city’s sea walls amplified the dimensions of the disaster.

In the accounts, this quake is followed by a severe one in 1556, and by strong ones in 1648 and 1659. Lesser quakes are recorded in 1690, 1712, 1719, 1752, and 1754, though even they were bad enough to cause some loss of life and property. The earthquake that struck, also in the early morning hours, on May 22nd 1766 was another big one that was vividly remembered by the city’s inhabitants for years afterwards. Mosques in the Fatih and Eyüp districts were demolished by the tremors and countless houses were leveled. The death toll numbered in the hundreds. The aftershocks from this quake are said to have continued for eight months causing severe psychological stress among the people of İstanbul.

The quake of 1766 was followed by minor ones in 1790, 1802, and 1837. A quake reported in 1841 is said to have shaken the city three times, toppling many buildings and causing loss of life. The quake of 1855 on the other hand caused relatively minor damage in the city.

The quake of '94

İstanbul street scene after the quake of 1894.

The worst earthquake to hit İstanbul before the 1999 one took place on July 10th 1894. Compared with previous ones, this quake is relatively well documented. Three shocks, lasting thirteen seconds in all, ran through the city from south to north. The quake’s epicenter was located in the Sea of Marmara about 8 kms offshore from Yeşilköy on the European side of the city. On the Richter scale we use today, the quake’s magnitude would have measured about 7.

Beyazit Square after the quake of 1894.

According to official figures, 138 people were killed; the damage to property was less severe though the Mihrimah Sultan mosque, the Covered Bazaar, and many public buildings suffered considerably.

Two views of the Grand Bazaar after the quake of 1894.

In this century, İstanbul sustained minor earthquakes whose magnitude was never less than 5.0 in 1923 (twice), 1952, 1957, 1963, and 1988. The earthquake that hit on August 17th caused something less than a thousand deaths and three times that number of injuries in the city. Nearly all the property damage was located to the Avcılar district and its immediate surroundings and was confined to buildings put up in the last decade or so.

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