All You Need to Know About 1999 Istanbul Earthquake



The 1999 Istanbul Earthquake is a 7.6 magnitude earthquake that took place near the Gölcük district of Kocaeli at 03:01:40 on August 17, 1999. Due to the 37-second 1999 Istanbul Earthquake, 17 thousand people lost their lives and more than 500 thousand people were left homeless. Istanbul, Kocaeli, Istanbul, Yalova, Bursa, and Sakarya were the places where the material and moral effects of the 1999 Istanbul Earthquake were felt the most.

The earthquake that caused massive destruction in the most advanced and extensive industrial field of Turkey caused serious danger due to the leak in the oil refinery in Kocaeli. On 19 October 1999, the authorities announced that 17,127 people died and 43,959 people were injured in the 1999 Istanbul Earthquake. Some sources suggested that the number of people who died was around 45 thousand. In the report dated September 1999, it was stated that 120 thousand houses became unusable, 30 thousand houses were badly damaged, 2 thousand buildings collapsed and 4 thousand buildings were damaged. The report also noted that 300,000 people were homeless.



1999 Istanbul Earthquake occurred on the North Anatolian Fault Line. The Anatolian Plate is cramped between the Eurasian and Arabian Plates and shifts approximately 2 to 2.5 cm westward each year. major earthquakes occurred on the North Anatolian Fault in Turkey occurs and East Anatolian Fault. Due to the 1999 Istanbul Earthquake, a 150 km-long break occurred in the fault line extending from Düzce to İzmit Bay. In the 1999 Istanbul Earthquake, especially the Avcılar district of Istanbul was severely damaged due to the sedimentary rock ground.

Due to the earthquake, 20 viaducts, 5 tunnels, and some overpasses on the European E-road E80 were destroyed. The Istanbul Earthquake created 2.5 meters of tsunami waves in the Sea of ​​Marmara. 155 people lost their lives due to the tsunami. 24 to 48 hours after the 1999 earthquake in Istanbul, welfare associations from 12 countries came to Turkey. A special team came from England to stop the leak in the Tüpraş Refinery. US President Bill Clinton visited Istanbul and Izmit.

There are many interesting and unexplained events allegedly happened during the 1999 Istanbul Earthquake. But the veracity of these narratives is controversial and there is no evidence that they are true. Many people say that on the night that connects August 16, 1999, to August 17, 1999, there were enough stars in the sky as if they could be caught with hand. There are also some rumors that a fireball was seen around Izmit Bay during the earthquake. Some people say that he witnessed paranormal events on the morning of 1999.

Detailed Information About 1999 Istanbul Earthquake


The 7.4 magnitude earthquake that occurred in 1999 on the night of August 16 to 17 was recorded as the second-largest earthquake in the history of Turkey. The earthquake, whose epicenter was Gölcük, was felt throughout the Marmara Region. The earthquake that occurred with the breaking of the North Anatolian Fault Line caused the loss of life and property in Istanbul, Bolu, Bursa, Eskişehir, Kocaeli, Sakarya, and Yalova. The earthquake that occurred on the western side of the North Anatolian Fault line which passes through the northern regions of Turkey started at 03:01 am on Tuesday, 17 August 1999, and lasted 45 seconds.



The epicenter of the earthquake was announced as the Gölcük district of İzmit. Its size is 7.6 according to the Richter scale by the US Geological Survey (USGS); It was measured as 7.8 by the Boğaziçi University Kandilli Observatory. However, today the magnitude of the earthquake is generally accepted as 7.4, which was announced in the first statements, and this measure is used. August 17th earthquake in Turkey in terms of size was recorded as the second largest earthquakes occurred. It was determined that the earth’s crust moved to the right during the 17-kilometer-deep shaking and broke along a 120-kilometer line.

Geological View of 1999 Istanbul Earthquake


In the report published three months after the earthquake, the Chamber of Geological Engineers wrote that the areas passing over the fault shifted to the right and forward by about 4 meters. In the same report, it was stated that after the rupture in the main epicenter in Gölcük, it is thought that another earthquake base in the Arifiye region located further east on the same fault zone may have been activated. About three months after the 17 August earthquake, another earthquake occurred, this time on 12 November, on the North Anatolian Fault Line, with Düzce as its epicenter. 845 people died in Düzce Earthquake, which was 7.2 magnitude and lasted 30 seconds.

These two earthquakes within three months over magnitude 7 occurred, risk, and especially to occur in the south of the fault line in Istanbul has caused more to the discussion of measures to be taken against the expected break in Turkey. August 17th earthquake, as well as population density, should also affect Turkey’s most important region in terms of economic activity. According to official figures, 18 thousand 373 people lost their lives and 48 thousand 901 people were injured in the earthquake. 5 thousand 840 people also disappeared. However, local people argue that the loss of life is much higher. Unofficial sources claim that the loss of life was around 50 thousand.



In some places, such as Gölcük, Değirmendere, and Karamürsel, located in the south of İzmit Bay, the parts close to the beach being submerged under sea waters due to an earthquake are shown as the most important factor that makes it difficult to determine the loss of life and damage. According to the statement made by the Prime Ministry Crisis Center a few months after the earthquake, most casualties were in Gölcük with approximately 4,500 people. While the recorded loss of life in Kocaeli was 4 thousand, approximately 2 thousand 500 people died in Yalova and Sakarya. 976 people lost their lives in the Avcılar district of Istanbul, which was affected by the earthquake.

In the report published in July 2010 by the Assembly Research Commission Established to Investigate the Risk of Earthquake and Determine the Measures to be Taken in Earthquake Management, it was stated that 364,905 houses and workplaces were destroyed or damaged at various levels in the earthquake. A significant portion of the casualties was the result of buildings being destroyed or severely damaged. The Chamber of Geological Engineers, in its report published in 1999, listed the three most important factors that increase the loss of life as follows:

  • Active Fault Zone: Although the active fault line is known in advance, the dense settlement and high population potential along this line have increased the damage and loss of life. As it moves away from the fault zone, it is observed that there is no or very little damage especially on the slopes and mountain foothills.
  • Wet Alluvial Ground: Between Bolu and Yalova, the fault zone and its immediate surroundings are composed of extremely soft and loosely attached clay, sand, and gravel deposits and alluvial ground. Such floors have negative features that will increase the current earthquake intensity several times.
  • Construction faults: The zone is within the boundaries of the 1st-degree earthquake zone. In this case and while complying with earthquake regulations is compulsory, a significant part of the heavy damage and high-rate casualties in earthquakes are caused by construction errors, incorrect foundation designs that do not comply with the ground conditions, bad workmanship and building material defects and rottenness used in construction.

Economical Outcomes of 1999 Istanbul Earthquake


The August 17 earthquake also had serious negative effects on the economy. According to the calculations made by different institutions, the economic cost of the earthquake varies between 12 and 20 billion dollars. The State Planning Organization calculates this cost as 15-19 billion dollars, the World Bank as 12-17 billion dollars, and the Turkish Industry and Business Association (TÜSİAD) as 17 billion dollars. After the earthquake, the need for external resources increased, especially due to restructuring efforts, and the suspension of production activities for a while in the industrial zone caused the economy to shrink.

Turkey’s largest oil refinery Tüpraş took the fire for days. Some studies show that the impact of the 1999 earthquake was among the effective reasons for the 2001 economic crisis. After the first shock caused by the earthquake was over, the focus was on search and rescue activities in the first place and debris removal after a while. In addition to public organizations such as the Red Crescent and Civil Defense Units, private and voluntary groups such as the Search and Rescue Team (AKUT) also played an active role in aid efforts. In addition, aid workers came from many countries, including Britain, Greece, the USA, and Japan.



At that time, the coalition government formed by the Democratic Left Party (DSP), Motherland Party (ANAP), and Nationalist Movement Party (MHP) was heavily criticized for being late in sending aid teams and supplies to the places hit by the earthquake. It took days for rescuers to reach some places. Debris removal efforts continued for months at some points. After August 17, the earthquake has become the subject of Turkey’s most important agenda item. The government under the prime minister Bülent Ecevit has enacted a series of legal regulations both to be used in post-earthquake relief and rescue efforts and to eliminate the effects of the economic damage caused by the earthquake. Among the arrangements made were the following:

  • A number of new taxes were introduced, especially the Special Communication Tax, and most of these taxes are still in effect.
  • The National Earthquake Council, consisting of 20 scientists and researchers, was established but was dissolved in 2007.
  • Earthquake containers were placed in many points of Istanbul and meeting areas were determined. Most of the determined gathering areas were later opened to development.
  • Earthquake insurance has been made compulsory
  • The number of search and rescue teams across Turkey increased
  • A number of changes were made to the zoning laws. After the earthquake, the earthquake resistance principles and control rules of the buildings were changed. In 2007, 2012, and finally, in 2019, serious changes were made in the regulations.

The Heavy Loss Caused by the 1999 Istanbul Earthquake


It has been 21 years since the painful earthquake of 17 August 1999, when tens of thousands of people died, were injured and disabled, and the economy was hit hard. The Marmara earthquake, whose epicenter was in Gölcük district of Kocaeli, and occurred at 03.02 local times, was felt in a wide area from Ankara to Izmir. According to official reports, 17 thousand 840 people died, 23 thousand 781 people were injured and 505 people were disabled in the earthquake of 7.4 magnitudes, which lasted about 45 seconds. In the earthquake that caused great loss of life and property, 285 thousand 211 houses and 42 thousand 902 workplaces were badly damaged.

While most citizens were caught in the earthquake sleep that took place in the late evening, the buildings not being made resistant to earthquakes, especially in Kocaeli Gölcük, and the use of wrong and incomplete materials caused a high loss of life and property. Turkey’s place in the Marmara earthquake, which is an important industrial region, has caused significant financial damage in wide geography, was a blow to the national economy. About 23 percent of Turkey’s population was living and 34 percent of GDP was being created in the area where the earthquake was effective.



Considering factors such as 46 percent of the value-added created in the industry emerged in the earthquake zone, 58 percent of the tax revenues in the budget occurred in the region affected by the earthquake, and the region’s per capita being higher than the average of the country, financial losses are more clearly revealed. The economic effects of the 1999 Istanbul Earthquake were a blow to the macro-economic indicators such as GDP, employment, growth, and public expenditure as well as the tourism sector that provide a significant amount of foreign currency entry for the economy. After the 1999 Istanbul earthquake, Turkey’s tourism revenues decreased by 40 percent compared to the previous year.

In various studies conducted by the Turkish Industrialists and Businessmen Association (TÜSİAD), State Planning Organization (SPO), and the World Bank, the values ​​of the macroeconomic costs of the 1999 Gulf Earthquake and the impact of the earthquake on the economy are clearly seen. The impact of the earthquake on the economy is $ 17 billion according to TUSIAD, $ 15-19 billion according to SPO, and $ 12-17 billion according to the World Bank. In this context, according to the evaluation of TÜSİAD, the earthquake caused the loss of 9 percent of the GDP, while this number is 8 to 10 percent according to the SPO, and 6.3 to 9 percent according to the World Bank.



Cash assistance of 161.6 trillion Liras was received for the damages caused by the Marmara earthquake, and 156.6 trillion Liras were spent. According to the examination of the earthquake accounts of the Prime Ministry Inspection Board, the amount accumulated in the central account opened with Ziraat Bank for the earthquake that took place on 17 August 1999 reached 161 trillion 665.6 billion Liras as of October 1, 2001. A total of 156 trillion 520.4 billion Lira was spent from this account, while the rest was transferred to the Disaster Fund, the Disaster Regional Coordinator, and other institutions and organizations for post-earthquake services.

After the Marmara earthquake, a loan of approximately 3.5 billion dollars was obtained from various countries and international financial institutions. With the loans provided from abroad, a total of 75 projects and sub-projects were financed for the earthquake zone, where Kocaeli, Istanbul, Bolu, Düzce, Yalova, and Sakarya are located. The credits in question were generally used in the earthquake region for housing construction and new housing networks, new hospital constructions and rehabilitation of health units, primary school constructions, renewal of transportation systems, especially rail and road, and financing support to SMEs. Even though, it was really tough to get back to normal life after such a horrible event. Still, helps and aids from the environment is very good both for social solidarity and for togetherness. That is why all countries, even every person who can, should help the people affected by an event like this.

Quantitative Information About 1999 Istanbul Earthquake


The 17 August earthquake was felt throughout the Marmara Region, in a wide area from Ankara to Izmir. According to official reports, there were 17,480 deaths and 23,781 injuries. 505 people were disabled. 285,211 houses and 42,902 workplaces were damaged. In addition, with 133,683 collapsed buildings, approximately 600,000 people were left homeless. Approximately 16,000,000 people were affected by the earthquake to varying degrees. Therefore, it is one of the most important events which deeply influenced the recent history of Turkey. The earthquake is one of the biggest earthquakes of the last century in terms of both the size, the width of the affected area, and the material losses it caused. The fact that the earthquake occurred in the Marmara Region, which is an important industrial zone of the country, and affected very wide geography caused great difficulties in the country.

The earthquake, measuring 7.5 Mw on the Richter scale, occurred at 3:02 am, in the region described by 40.70 north latitude and 29.91 east longitude, 11 km southeast of Izmit. Although the magnitude of the earthquake has been reported by various institutions at different values, the magnitude of the moment intensity varies around Mw = 7.5 and the surface wave magnitude Ms = 7.7. In the Gölcük earthquake with official figures; While a total of 17.480 people lost their lives – 270 in Bolu, 268 in Bursa, 86 in Eskişehir, 981 in Istanbul, 9.477 in Kocaeli, 3.891 in Sakarya, 2.504 in Yalova and 3 in Zonguldak, in the Survey Report of the Assembly that was published in 2010, the number of buildings destroyed and severely damaged in this earthquake was corrected as 96.796 houses and 15.939 workplaces in addition to 48 thousand 901 injured and 505 disabled people.



The fact that the earthquake occurred in the Marmara Region, an important industrial zone of the country, and affected very wide geography, caused great difficulties in the country. The earthquake occurred on August 17, 1999, at 3:02 am, in the region defined by 40.70 north latitude and 29.91 east longitude, 11 km southeast of Izmit. Although the magnitude of the earthquake has been reported by various institutions at different values, the magnitude of the moment intensity varies around Mw = 7.5 and the surface wave magnitude Ms = 7.7.

  • Body Wave Intensity = 6.3 (USS)
  • Surface Wave Intensity = 7.8 (USGS)
  • Moment Intensity = 7,5 (Kandilli, USGS, General Directorate of Disaster Affairs, Earthquake Research Department, DGCA-DAD)
  • Record Duration Intensity = 6.7 (Kandilli)

It was determined by the investigations that the focal depth of the earthquake was 10-15 km and a fault movement occurred around 120 km with right-slip. After the main earthquake wave, many aftershocks with magnitudes of 4.0-5.0 occurred. Nearest momentum has shifted to the earthquake epicenter, General Directorate of Disaster Affairs Earthquake Research established all across Turkey by the Office of Records and Strong Motion Network, which is operated in a station that is taken from Izmit Meteorological Station. Accordingly, the maximum acceleration is 163 mG in the north-south direction, 220 mG in the east-west direction, and 123 mG in the vertical direction. All three components are of comparable size to each other.



In the recent past, severe earthquakes occurred in this region in 1943, 1957, 1967, including the Adapazarı epicenter. When we look at the history of the past, there are big earthquakes in this region every 30 years on average. After the 1999 earthquake, the expectation of earthquakes of various magnitudes in certain periods and various magnitudes is due to the characteristic feature of this fault line. After the earthquake, some regulations such as compulsory earthquake insurance were introduced.

The 99 earthquakes that affected the Marmara Region had a great impact all over the world. In total, 52 countries helped. Those countries are Germany, the United States of America, Azerbaijan, Bangladesh, Belgium, the United Arab Emirates, the United Kingdom, Algeria, Morocco, Finland, France, Georgia, Iraq, Israel, Sweden, Italy, Japan, Cyprus. Greek part, TRNC, Hungary, Malaysia, Egypt, Pakistan, Russia, Saudi Arabia, Jordan, and Greece.

A Remarkable Research on the 1999 Istanbul Earthquake


Scientists from Boğaziçi and Stanford University reached new findings in the research on the usability of pioneering tremors in earthquake prediction in the light of the findings of the August 17 earthquake. According to the research, a total of 18 forescent earthquakes with magnitudes 0.9 to 2.8 occurred in a seismic station a few kilometers away from the earthquake outer center, recorded 44 minutes before the 7.6 magnitude earthquake. The last leading earthquake occurred just before the big break. According to the research results, the 1999 earthquake occurred with the domino effect of the earthquakes on the fault.

Academics from Boğaziçi University and Stanford University conducted a new study by reviewing the data on the 17 August 1999 Izmit earthquake, in which more than 17 thousand people died. In the new study, published in the June 2018 issue of the journal Nature Geoscience, it was discussed whether the possibility of a larger earthquake could be predicted by the leading tremors before the earthquake.



A study previously published in Science magazine in 2011 concluded that the 1999 Izmit Earthquake came after a series of small pioneering tremors, and these pioneering tremors were potential warning signs that a major earthquake would occur. However, joint research conducted by scientists from Boğaziçi and Stanford Universities has yielded staggering results about whether the pioneering tremors have an impact on earthquake prediction.

“We evaluated the 1999 Izmit earthquake and seismic data with new techniques that were not used that day,” said Dr. Fatih Bulut, a faculty member at Boğaziçi University Kandilli Observatory and Earthquake Research Institute, Department of Geodesy. As a result of our research, we found that the forerunners were like any other small earthquake. “There was no distinctive indication of the way these pioneering tremors occurred, indicating that a major earthquake would happen,” he said.

“We want to find a scientifically valid way to warn the public before an earthquake occurs,” said William Ellsworth, a professor of geophysics, who participated in the research from the Stanford University School of Earthquake, Energy and Environmental Sciences. However, our research does not reach an optimal result in terms of earthquake prediction. Despite this, thanks to the pioneering tremors, we have become able to understand the earthquake onset physics in much more detail. ” Adding that in at least half of all major earthquakes, earthquakes occur after small leading tremors, Ellsworth said, “The predictability of the earthquake through these pioneering tremors depends on the separation of these pioneering tremors from ordinary earthquakes. “The research, published in the June issue of the journal Nature Geoscience, opens a whole new window on the way the earthquake occurs.”



Stating that they focused on the question of how earthquakes occur in the research, Fatih Bulut said, “The main objectives of this study were to understand the onset physics of earthquakes and to examine the predictability of earthquakes with pioneering tremors, which have been discussed for a long time. Pioneering tremors are one of the most important data sources that provide an explanation for how earthquakes occur. In 2011, French and Turkish geoscientists conducted a study for Science magazine analyzing the pioneering tremors of the 7.6 magnitude earthquake that took place on August 17th. According to the research, a total of 18 precursor earthquakes with magnitudes between 0.9 and 2.8 occurred at a seismic station a few kilometers away from the earthquake outer center, recorded 44 minutes before the 7.6 magnitude earthquake. “The last pioneering earthquake occurred just before the big break,” he explained.

According to the analysis of the Scientific research, the pioneering earthquakes occurred at a point about 15 kilometers below the earth, very close to the beginning of the 7.6 magnitude earthquake. In addition, the similarities in waveform and depth were interpreted as the benefit of 18 pioneering earthquakes occurred at the same point. Therefore, the researchers concluded that a “slow slip” occurred in the Izmit Earthquake. In other words, the rapid acceleration of the slide triggered the 7.6 magnitude earthquake. Research by monitoring similar slow slip events in Turkey and other active fault lines in the world can provide timely warnings were predicting big earthquakes before they occur. In our research, we decided to test this idea. “We have clearly seen that this is not the case with the results we have reached and that the 1999 Earthquake cannot be predicted by pioneering tremors.”

Instead of relying on data from a seismic station, Fatih Bulut and William Ellsworth used data from 10 stations, 100 kilometers in diameter, of the earthquake outer center that recorded the 1999 earthquake. Stating that they were able to determine the exact location of the earthquakes with the data they received from these 10 stations, Fatih Bulut said, “Since 44 minutes before the main earthquake, we detected a total of 26 pioneering earthquakes moving from west to east along the fault line. We have seen that all pioneering earthquakes occurred at close but different points from the fault line and none of them repeat. Our result shows that an earthquake occurs by triggering another earthquake at another adjacent point, as we call the multi-part rupture model.



In a sense, the 1999 earthquake occurred with the domino effect of the earthquakes on the fault. Thousands of occurring each year in the vanguard of the Izmit earthquake in Turkey can be distinguished from small earthquakes that have any qualifications. “The last earthquake that occurred one after another triggered the 7.6 magnitude earthquake,” he said. Fatih Bulut and William Ellsworth concluded that the slow sliding event had no effect in triggering the Izmit Earthquake and that the leading earthquakes were unqualifiable. Emphasizing that all the leading earthquakes occurred in different places along the fault line, William Ellsworth said, “None of these were repeating in a way that a great earthquake was coming.

Science research authors were overly optimistic about this, but what they claimed did not happen. Whether leading or not, we cannot say whether there will be a locally negligible small earthquake after a small earthquake or a large earthquake affecting a large area like the 1999 Izmit Earthquake. We do not even know why some major earthquakes have leading earthquakes but some do not. We continue our research on these issues. “The way to move forward is to make observations very close to the earthquake source with advanced instrumental equipment.”

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Savaş Ateş

I'm a software engineer. I love Istanbul. I have been to 10 different countries. Istanbul is in the top 3 cities. I like to play soccer too :)

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