The December 28, 1908, Messina Straits, southern Italy, earthquake: Waveform modeling of regional seismograms

Tho 1908 Messins Straits earthquake is one of the most catastrophic events in history. There were 60,000 to more than 100,000 deaths, and the cities of Messina and Reggio Calabria, on the opposite sides of the straits, were almost completely destroyed. During the last decades only low magnitude events occurred in the area. The 1908 earthquake is then crucial for understanding the mode of stress release in the area. We collected and digitized several regional seismograms of this event recorded in central Europe with the aim of studying the source characteristics. In order to separate the path effects, we analyzed recent events with simple and known sources. Owing to the small azimuth range spanned by the available stations, we could not determine a fault plane solution for the Messina Straits event, nor discriminate between the published focal mechanisms. However, the normal fault character of the rupture is confirmed. By inverting the historical P waveforms we derived source time functions. and obtained seismic moment of 5.38 (+/-2.16) x 10(19) N m (M-w=7.1). This is in good agreement with the results obtained by several authors from the inversion of the historical leveling data. This value is confirmed by the SH wave modeling, which also allowed the assessment of the unilateral northward character of the rupture propagation along an similar to 43 km fault. Finally, we applied it simple rupture model in order to derive the slip distribution along the fault. The resulting function is in good correspondence with the geodetic inversions performed by Boschi et al. [1989] and De Natale and Pingue [1991]. In particular, a maximum slip of similar to4 is located in proximity of the center of the slipped area. The high dislocation patch beneath the Messina harbor, as depicted by De Natale and Pingue, is not confirmed by our analysis and is probably connected to surface collapse of some of the bench marks.