Earthquake Early Warning System for the Marmara Region

Earthquake early warning has been a longstanding effort of the Kandilli Observatory and Earthquake Research Institute (KOERI), beginning in 1998 with the establishment of the Istanbul Earthquake Rapid Response and Early Warning System. Building on this experience and benefiting from advances in seismic instrumentation and data transmission technologies, KOERI has recently developed a new-generation early warning system
(EEWS) that is currently operational across Türkiye; however, given  the high seismic hazard associated with the North Anatolian Fault and its offshore segments in the Sea of Marmara, the present current station density, spatial coverage, and communication latency characteristics, the generation of reliable and timely public warning messages is presently feasible primarily in the Marmara region.
Earthquake detection, location, and magnitude estimation are performed using the Virtual Seismologist algorithm developed within the TRANSFORM project (funded by the European Union under project number 101188365; Cua, 2005; Cua and Heaton, 2007; Cua et al., 2009). Alerts are issued once seismic signals are recorded at a minimum of four stations. System performance is evaluated using the 2 October 2025 Mw 5.0 Marmara Sea earthquake as a case study. The first early warning alert was issued 8.4 s after the earthquake origin time, providing more than 20 s of warning for the Anatolian side of Istanbul prior to the onset of strong ground shaking. The installation of real-time seafloor seismic stations in the Sea of Marmara is therefore expected to substantially reduce detection times and further enhance the overall effectiveness of the Earthquake Early Warning System (EEWS) in the Marmara Region. These results demonstrate the capability of the KOERI-EEWS to deliver timely alerts and highlight its potential to enhance seismic risk mitigation and the protection of critical infrastructure.