Inversion of source parameters from near- and far-field observations: An application to the 1915 Fucino earthquake, central Apennines, Italy

We use a nonlinear inversion approach for determining source parameters of the Fucino M-s = 6.9 earthquake that occurred along central Apennines, Ital y, in 1915, taking into account both near-field surface deformations and fa r-field first-motion polarities. This event was one of the most destructive in Italy this century, causing over 30,000 casualties. Altitude and leveli ng measurements were performed before (1862) and after (1917) the event, al ong a circular route consisting of 18 benchmarks. Polarities of first arriv als do not constrain a unique fault-plane solution, while the one obtained by inverting geodetic data, with relevant constraints provided by neotecton ic data, disagrees with P wave polarities. Our joint inversion, based on a robust fitting technique, has resulted in only one well-defined solution, s atisfying geophysical data as well as surface-faulting distribution and pal eoseismological information.