Stochastical and Mathematical Modeling of Long-term Interaction among Earthquakes and between Earthquakes and Volcanic Eruptions

Dottorato di Ricerca in Geofisica, XVII Ciclo, Università di Bologna

At first, we investigate on the physical mechanisms responsible for for long-term interactions. It has been argued that postseismic relaxation field might be responsible of such long-term interactions; then, our first task is understand whether or not the postseismic stress field can produce not negligible perturbations (respect to the tectonic field) and lead to long-term variations on a seismogenetic system.
The second task of this work is to systematically investigate on the effects of long-term interactions in the seismic data. In particular, we focus our attention on the perturbation induced by the greatest earthquakes of the last century, all occurred in the period 1952-1965.
At global scale, we study the distribution of strong earthquakes (M ≥ 7.0), and specifically we try to understand whether spatial and temporal distribution of M ≥ 7.0 earthquakes occurred after 1965 is correlated with the perturbation due to the 5 giant earthquakes Kamchatka 1952, Aleutins 1957, Chile 1960, Alaska 1964, and Aleutins 1965.
At local scale, we aim to understand the effects of long-term interactions on moderate seismicity. In particular, we study the effects of the two strongest event of the past century (Chile 1960 and Alaska 1964) in Southern California, where is available a catalog (complete with focal parameters estimation) for moderate seismicity (M ≥ 4.7) since 1933.
Finally, we study the effects of long-term stress perturbations on volcanic systems. The interaction between strong tectonic earthquakes and volcanic eruptions has been found through various statistical analysis of catalogs [e.g., Linde and Sacks, 1998; Marzocchi, 2002; Marzocchi et al., 2002]. Anyway, some authors remain skeptical because of the retrospective approach used in those works. Therefore, here we aim to set an objective tool to accomplish a forward test to quantitatively analyze such a long-term interaction among earthquakes and volcanoes.