Earthquake early warning for Bucharest, Romania:: Novel and revised scaling relations

The accumulation of strong earthquakes with resembling source mechanisms in the Romanian Vrancea zone, SE Carpathians, allows for designing a simple, cheep and robust earthquake early warning (EEW) system for Bucharest with leading times of about 25 s. A previously established scaling relation for EEW predicts in the range from 1 - 2 s a ten times higher ground motion amplitude in Bucharest than the maximum P-wave acceleration measured in the epicentral area. Using additional weak and strong motion data, we find that ground shaking in Bucharest is generally overestimated by this relation by a factor of two. However, the predicted amplitudes are within the 95% confidence interval of our revised relation. Additional predictive laws for EEW are determined for different ground motion parameters. The application of our scaling relations to the October 27, 2004 Vrancea earthquake (M-w = 6.0) supports the feasibility of the approach for EEW in Romania.