Examination of a relationship between atmospheric blocking and seismic events in the Middle East using a new seismo-climatic index

Abstract

This study statistically examines the role of atmospheric blocking as a precursor of major seismic events. Atmospheric blocking archive and earthquake databases for the Middle East region are compiled for 2000–2013. Correlations between atmospheric blocking events and seismicity are examined based on defined seismo-climatic index (SCI) based on variations of earthquake frequency and magnitude before and after blocking events. Limiting the SCI index to values > 6, 16 out of 26 major earthquakes (M > 6), i.e. 62%, are shown to have occurred within 14 days after blocking events over their respective epicentral regions. The correlation between blocking events and subsequent seismicity falls into a range of 0.694–0.803. Additional blocking-related atmospheric anomalies such as cyclogenesis, cloud coverage, and anomalous rainfall prior to major earthquakes can be understood as processes that take place in the Earth’s crust and at the ground-to-air interface as a result of the stress activation of positive hole charge carriers at depth, in the hypocentral rock volume, and their rapid migration to the Earth’s surface. Hence, atmospheric blocking events in a seismically active region may be categorized as an earthquake precursory phenomenon.