A Reappraisal of the Seismicity of Sardinia, Italy

Abstract

In popular opinion, Sardinia is the only nonseismic region of Italy. Most researchers are likely to agree, up to a point. Geology-wise, the Sardinia–Corsica block is among the stablest areas of the Mediterranean. History-wise, up to 2011, only one Mw 5.1 event located offshore Sardinia was listed by Italian seismic catalogs (13 November 1948). Seismic networks record only a few, low energy (Mw < 5) events, mostly located off- shore and with little or no effects on land. Seismic hazard in Sardinia is very low. “Low,” yes, but not “totally lacking.” We present the results of a recent reappraisal of Sardinian seismicity. We gathered information on three major earthquakes (1616, 1771, and the 1948–1949 sequence). Another sequence (January–March 1901) was re-evalu- ated, identifying its previously unknown main event. It was confirmed that some earth- quakes (1870, 1906, 1922, and 1924) had low magnitudes and scarce to nil macroseismic effects, whereas some other turned out either very doubtful or wholly fictitious (1835, 1838, 1855, and 1898). The seismic hazard of Sardinia can now be reassessed on a sounder basis than before. We hope that our work will help the people of Sardinia to improve their awareness of living in a seismic land, if with a low level of seismicity.