Search

Terra Nova, 24, 52-61, 2012 Abstract We have analysed the history of seismic activity in the region of L'Aquila to compare the 2009 sequence with previous ones. Historical catalogues are exhaustive for large shocks, but not for small earthquakes and swarms. Our original compilation highlights repeated seismic sequences from 1315 ad to present. In the 20th century, at least 23 sequences affected the Abruzzi region, 8 of which were very close to L'Aquila. In previous centuries, we found evidence of at least 13 sequences around L'Aquila, with maximum magnitude ∼4 to ∼5. Only three sequences were followed by stronger shocks (1461, 1703 and 2009). However, many strong events of the region (1349, 1762, 1915, 1950) were not preceded by foreshocks. We describe here the last of these sequences (1985) showing its strong similarity with the 2009 one, except its final evolution (no large event in 1985). Our analysis suggests that seismic sequences alone cannot be considered straight forerunners of incoming strong events. [ABSTRACT FROM AUTHOR]

Terra Nova, 00, 1–7, 2009 Using the non-extensive statistics, the analysis of the magnitude distribution of the 2005–2009 seismicity of L'Aquila area (Central Italy), struck by a strong earthquake ( ML = 5.8) on 6 April 2009 (1:32 UTC), was performed. This was the strongest event of the sequence. The analysis of the frequency magnitude distribution of three time intervals – (1) from 16 April 2005 to 30 March 2009, (2) from 30 March 2009 to 6 April 2009, and (3) from 6 April 2009 to 1 July 2009 – reveals that the non-extensivity parameter q increases in the seismic interval (2), before the occurrence of the strongest L'Aquila event, indicating an increase in the degree of out-of-equilibrium state before the occurrence of the strongest event. [ABSTRACT FROM AUTHOR]