P- andS-velocity anomalies in the upper mantle beneath Europe from tomographic inversion of ISC data

Abstract

S U M M A R YWe present a new tomographic model for P-and S-velocity anomalies beneath Europe (30 • N-55 • N, 5 • W-40 • E), extending in depth up to 700 km and constrained by inversion of data from the International Seismological Center (ISC) catalogue. The algorithm uses the traveltimes from events located in the study area recorded by all available worldwide stations, as well as times from teleseismic events recorded by European stations. The events from the ISC catalogue have been relocated and combined into composite events. All the traveltimes were corrected for crustal structure using the reference model EuCRUST-07. The resulting velocity anomalies show similar large-scale patterns as observed in previous studies, but have a higher resolution, which allows detection of some features in more detail. For example, it is now possible to assess the depth extension of the small slow velocity body beneath the Eifel region and Eger graben. The P and the S model show a good consistency in the uppermost 200 km below most of the European area and in some parts even in the deeper layers (e.g. beneath the Apennines and the Hellenic arc). The new model provides clear images of some principal features, which were previously detected in a limited number of studies, while the comparison between P-and S-velocity anomalies provides novel constraints to address on their nature (e.g. the gap in the Adriatic plate subducted below the central-southern Apennines). In this paper, we pay special attention to testing the reliability of the results. The random noise effect is evaluated using a test with independent inversion of two data subsets (with odd/even events). The spatial resolution is estimated using different checkerboard tests. Furthermore, we present a synthetic model with realistic patterns, which reproduces after performing forward and inverse modelling the same shape and amplitudes of the anomalies as in the case of the real data inversion. In this case, the parameters of the model can be used to assess the amplitudes of P and S anomalies that is critical for evaluation of other petrophysical parameters (temperature, density, composition, etc.) in the upper mantle.

Multiscale Seismic Tomography Imaging of Volcanic Complexes

“…The calculations were separately performed in 12 overlapping circular windows and then the results were composed by averaging in one model. The reliability of this model was thoroughly verified by a number of different tests presented in Koulakov et al, (2009a). Note that this model seems to be consistent with regional and global models constructed by other authors (e.g.…”

“…This model was computed by Koulakov et al, (2009a) from inversion of several millions of travel times from the ISC catalogue based on the regional tomographic scheme (Figure 1). The calculations were separately performed in 12 overlapping circular windows and then the results were composed by averaging in one model.…”

“…5. The distribution of P velocity anomalies in the uppermost mantle beneath Europe and Mediterranean, just below Moho, from regional tomographic study by Koulakov et al, (2009a). Main geographic and tectonic elements in the study area modified after Faccenna et al (2003).…”

Segmentation of the Izu-Bonin and Mariana slabs based on the analysis of the Benioff seismicity distribution and regional tomography results

“…In later works, this algorithm was modified and used to study the upper mantle structure beneath some regions (see, for example, Koulakov et al, 2009a;Koulakov, 2011). This tomographic inversion algorithm is based on the linearised approach which implies that all calculations are performed on the basis of rays constructed in one-dimensional model AK135 (Kennett at al., 1995).…”

Subduction or delamination beneath the Apennines? Evidence from regional tomography

“…However, despite the large number of different tomography models, knowledge on the major tectonic processes is often ambiguous and contradictory. In this paper we present a new 3-D seismic model of the upper mantle beneath the Italian region constructed based on similar calculation schemes as those used in Koulakov et al (2009), but using a considerably larger data set. Based on the distributions of P and S velocity anomalies, we propose a new interpretation for the recent tectonic history of the Italian region.…”