Earthquake activity and hazard in the Carpathian Basin II

Abstract

Based on a complete dataset of the average magnitude M, the recurrence curve predicts an earthquake of magnitude M = 5 every one year, an earthquake of magnitude M = 6 every ten years, and an earthquake of magnitude M = 7 every one hundred years in the Carpathian Basin on average. The curve of elastic energy release of earthquakes does not indicate any noticeable periodicity in the Carpathian Basin based on the observations of nearly 500 years (1500- 1995). The average yearly energy release is 6.1E+13 joule in the whole Basin and the contribution of the Háromszék-Vrancea region to this amount is 4.8E+13 joule/year, while 1.3E+13 joule/year is the product of the remaining large part of the studied area. That is the vast portion of seismic energy is released in an area of only about 6% of the whole Carpathian Basin. According to the results of probabilistic seismic hazard estimations the highest hazard is expected in the region of Háromszék-Vrancea (Romania), where the expected peak horizontal ground accelerations 0.30g, 0.38g and 0.48g respectively will not be exceeded with 75% probability during 50, 100 and 250 years using s=0.5 value in the attenuation.