Mapping the Moho Across the Northern and Central Apennine Chain and Eastern Sicily - The Teleseismic Receiver Functions Method

摘要

Waveforms of seismic events occurred at epicentral distances ranging from 30 to 90 , and recorded by 3-component stations installed in peninsular Italy and in easternSicily, were analyzed using the receiver function technique. Receiver functions are timeseries where the arrivals of P-to-S waves converted at marked velocity contrasts beneath aseismometer are enhanced. Teleseismic receiver functions are frequently used to identifywaves converted at the Moho discontinuity to infer crustal thickness. Across the northernApennines, receiver functions show that west of this chain (i.e. beneath the Elba island andTuscany) the Moho is flat and shallow, while it deepens from the eastern coast of the peninsulatoward the chain. Two Ps conversions are observed at a station located in the Tiberinavalley, indicating the presence of the Moho at depths of about 20 and 52 km. More to thesouth, across the central Apennines, the Moho is shallower beneath the Tyrrhenian marginof the peninsula than beneath the Adriatic margin, and deepens from both sides toward theApennines. The largest crustal thickness is inferred in the area of highest topography. TheMoho depths estimated with the receiver function technique are in agreement with the interpretationof active seismic data in the western margin of peninsular Italy and along theAdriatic coast, while they are significantly larger beneath the Apennines. Results of an ongoingstudy in eastern Sicily show that Moho depth increases from north to south. In thisarea, the northernmost stations show a also a later Ps converted by a lower interface.