Reply to comment by G.F.Panza on "Rarely observed short-period (5-10s) suboceanic waves propagating across the Tyrrhenian Sea"

In Rovelli et al., (2004) we focused on spectacular, rarely observed recordings of suboceanic Rayleigh waves propagating across the Tyrrhenian Sea. These waves, observed in this region for the first time by Rovelli et al., (2004), exhibit periods of 5 to 10 s. We interpret the long duration and the amplification of the observed coda as due to the presence of the water layer coupled with a relatively fast seafloor. Because of the low attenuation of the water layer and the seafloor, these waves propagate efficiently across the Tyrrhenian Sea. Ewing et al. [1957] already observed longer period (T = 15 s) suboceanic Rayleigh waves propagating for thousands of kilometers in the Pacific ocean. Observations at shorter periods and smaller distances are rare. Moreover, we found that the Tyrrhenian suboceanic Rayleigh waves are generated by shallow earthquakes occurring beneath the seafloor. In our study, causative earthquakes are located offshore northern Sicily and recorded in peninsular Italy. Events with a similar path, located in central Italy and recorded in Sicily, do not show any coda. This indicates that offshore, shallow sources are able to excite the overlying water layer and that water plays an important role in transmitting energy efficiently through the seafloor. These features have never been considered in the papers quoted by Panza [2006].