In short: Six Istanbul earthquake scenarios modeled on ruptures of the Marmara Sea submarine faults show western Istanbul, including Atakoy, Bakirkoy and Avcilar, shaking more than three times harder than in the 1999 M7.6 Izmit earthquake, whose epicenter lay about 70 km away. Soft sediments amplified shaking there in 1999, when 37 seconds of motion killed about 17,000 people and left 250,000 homeless.
In 1999, the magnitude 7.6 quake devastated part of northwest Turkey, not far from Istanbul [~70 km (43 mi) away from the earthquake’s epicenter]. The 37 seconds shaking killed about 17,000 people and left 250,000 homeless. This unfortunate event was a wake-up call for the nation. Twenty years later, northwest Turkey is still under the threat of a major quake. Prof. Polat Gulkan and I studied six plausible earthquake scenarios that may impact Istanbul directly due to the rupturing of Marmara Sea submarine faults. We compared the ground shaking from these scenarios with the actual magnitude 7.6 Izmit event.
Our most frightening finding is that the West of the Istanbul Metropolitan area is expected to be shaken more than three times as it did during the Izmit earthquake. This part of the metropolitan including Atakoy, Bakirkoy and Avcilar districts experienced significant damage mainly due to the strong amplification of ground shaking from underlying soft sediments during the 1999 event.
The elevated earthquake risk for the Istanbul Metropolitan is not different than other big U.S. cities including San Francisco, Los Angeles, Portland, and Seattle.
Because the earthquake’s impact is so sudden, our response should be as quick as possible too. Today, technology reached a tipping point that revolutionary AI, advanced sensor technology and cloud-computing allow us to respond to earthquake disasters rapidly. By instrumenting buildings, bridges, dams and other infrastructure with sensors, and by using real-time data analytics, we can lessen much of the impact and suffer from earthquakes.
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Key Takeaways
- The 1999 M7.6 Izmit earthquake struck about 70 km from Istanbul, shook for 37 seconds, killed about 17,000 and left 250,000 homeless.
- Six rupture scenarios on Marmara Sea submarine faults were compared with recorded Izmit ground shaking.
- Western Istanbul (Atakoy, Bakirkoy, Avcilar) is expected to shake more than three times harder than in 1999.
- Soft underlying sediments amplified shaking in those districts during the Izmit event.
- Istanbul's elevated risk is comparable to San Francisco, Los Angeles, Portland and Seattle.
Frequently Asked Questions
The scenario study by Prof. Polat Gulkan and the author compared six plausible Marmara Sea fault ruptures with the recorded 1999 M7.6 Izmit shaking. The most alarming result is that the western Istanbul metropolitan area is expected to be shaken more than three times as strongly as it was in 1999. Because the Izmit epicenter was about 70 km away, a rupture directly beneath the Marmara Sea brings the source much closer to the city.
Districts such as Atakoy, Bakirkoy and Avcilar sit on soft sediments that strongly amplify ground shaking. That amplification already caused significant damage there in 1999, even though the Izmit epicenter was roughly 70 km away. In the modeled Marmara Sea scenarios, the rupture is closer to western Istanbul, and the same soft-soil amplification acts on stronger input motion, producing shaking more than three times the Izmit level.
The epicenter of the 17 August 1999 M7.6 Izmit earthquake was about 70 km (43 miles) from Istanbul, in northwest Turkey. Despite that distance, roughly 37 seconds of strong shaking killed about 17,000 people and left 250,000 homeless, and parts of western Istanbul suffered significant damage from soil amplification. The event became a national wake-up call about the seismic threat to the region.
The main threat comes from the submarine segments of the North Anatolian Fault beneath the Marmara Sea, directly south of Istanbul. The scenario study modeled six plausible ruptures of these Marmara Sea faults and compared the resulting ground shaking with the 1999 Izmit earthquake. The elevated risk is comparable to that facing large U.S. cities such as San Francisco, Los Angeles, Portland and Seattle.
Because earthquake damage happens within seconds, the response must be equally fast. Instrumenting buildings, bridges, dams and other infrastructure with sensors and feeding the data into real-time, AI-based analytics with cloud computing lets operators know immediately which structures were shaken hardest and which may be unsafe. That shortens inspection and emergency response, directs resources to the most affected districts and reduces loss of life and prolonged disruption.
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