A study on warning algorithms for Istanbul earthquake early warning system

Abstract

[1] 17 August (Mw 7.4) and 12 November 1999 (Mw 7.2) earthquakes have caused major concern about future earthquake occurrences in Istanbul and in the Marmara Region. Stress transfer studies and renewal model type probabilistic investigations indicate about 2% annual probability for a M w = 7+ earthquake in the Marmara Sea. As part of the preparations for the expected earthquake in Istanbul, an early warning system has been established in 2002. A simple and robust algorithm, based on the exceedance of specified threshold time domain amplitude and the cumulative absolute velocity (CAV) levels, is implemented for this system. Rational threshold levels related to new bracketed CAV window approach (BCAV-W) are determined, based on dataset of strong ground motion records with fault distances of less than 100 km, as 0.2 m/s, 0.4 m/s and 0.7 m/s related to three alarm levels which will be incorporated in the Istanbul earthquake early warning system. Citation: Alcik, H., O. Ozel, N. Apaydin, and M. Erdik (2009), A study on warning algorithms for Istanbul earthquake early warning system, Geophys. Res. Lett., 36, L00B05,

The Status of Earthquake Early Warning around the World: An Introductory Overview

“…It consists of 10 strong-motion instruments deployed along the northern shore of the Marmara Sea as part of the Istanbul Earthquake Rapid Response and Early Warning System (Erdik et al 2003). The current system is based on the exceedance of predefined thresholds of ground motions at two to three sensors before a warning is declared (Alcik et al 2009). The system is now operational and expects to start providing warning to several industrial users in 2010.…”

“…Istanbul also uses front detection. Ten instruments along the northern shore of the Marmara Sea trigger based on exceedance of an acceleration threshold at two or three sites (Alcik et al 2009). …”

Real-time numerical shake prediction and updating for earthquake early warning

“…The amplitude of P wave (Wu and Kanamori 2005;Kanda et al 2009), the dominant ground motion period, and average ground motion period (Nakamura 1988;Allen and Kanamori 2003;Wu et al 2007) are proposed to predict the upcoming peak ground motions. The systems have operated in many countries such as Japan for the general public (Hoshiba et al 2008;Hoshiba and Ozaki 2014) and have been investigated in the USA, Taiwan of China, the European Union, Turkey, and other countries and regions (e.g., Alcik et al 2009;Hsiao et al 2009;Gasparini and Manfredi 2014;Kuyuk et al 2013).…”

“…Front detection methods are often used to protect the city off the coast by installing one or more stations along the coast, such as Istanbul EEW system proposed by Alcik et al (2009) along the northern shore of the Marmara Sea. The front detection methods trigger a warning if the ground shaking exceeds a certain level, but cannot predict the intensity information for a specific region, thus cannot provide the severity order of the disaster.…”

Real-time 3-D space numerical shake prediction for earthquake early warning

“…The Seismic Alert System (SAS) for Mexico City at the Pacific coast uses the front detection method to provide approximate 60 s for earthquakes. The EEW system in Istanbul uses seismometers along the Northern shore of the Marmara Sea based on the front detection method (Alcik et al 2009). The front detection methods can provide warning if the epicenter is far from the city, but it cannot determine the magnitude or the severity of the earthquake.…”