GNGTS 2021 - Atti del 39° Convegno Nazionale

137 GNGTS 2021 S essione 1.3 ANISOTROPIC TOMOGRAPHY OF THE UPPER MANTLE UNDER THE CENTRAL MEDITERRANEAN WITH TELESEISMIC P-WAVE DELAYS F. Rappisi, B. P. VanderBeek, M. Faccenda Dipartimento di Geoscienze, Università degli studi di Padova, Italy Since the late 1990s, several seismologist have studied the Central Mediterranean region ai- ming at imagining the isotropic and anisotropic structures below its surface. This area represents one of the most interesting convergent margin on Earth, characterized by compressional and extensional tectonic domains that led to the current diversity of geologic settings. Although nu- merous researchers have demonstrated that neglecting anisotropy in P-wave tomography can introduce significant imaging artefacts, prior tomographic studies have largely assumed an iso- tropic Earth. In the present work we improve upon prior isotropic imaging of the Central Medi- terranean by performing 3D anisotropic P-wave tomography that includes dipping fabrics using the method proposed by VanderBeek & Faccenda (2021). Our results show that inverting for sei- smic anisotropy strongly reduces the magnitude of the isotropic P-wave anomalies. This suggests that lateral variations in temperature and/or composition are smaller that what can be inferred Fig. 1 - Horizontal map views of our best anisotropic model at (a) 100 km, (b) 200 km, (c) 300 km, and (d) 400 km depth. Isotropic anomalies are plotted with respect to starting model. Anisotropy is represented by ellipse symbols where the major axis of the ellipse parallels the fast-direction and the minor axis scales linearly with the symmetry axis dip into the view plane. Areas of poor data coverage are masked in grey. Adapted from Rappisi et al. 2022, in review. 1% 0º 30º 60º 2% 4% 100 km 200 km 300 km 400 km dlnVp (%) (a) (b) (c) (d)