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Three-dimensional seismic Structure

People:

Diana Latorre – diana.latorre@ingv.it

Raffaele Di Stefano – raffaele.distefano@ingv.it

Simona Carannante - simona.carannante@ingv.it

A main requirement for high-resolution (HR) earthquakes location is the availability of a good velocity model correctly imaging crustal complexities. The aim of this Task is the definition of a HR seismic structure of the study area by modelling the spatial distribution of body-wave velocities and the impedance contrasts associated to the main seismic horizons. To this goal we use seismic signals of local earthquakes recorded by the TABOO network.

Conventional tomographic techniques are applied for three-dimensional (3D) reconstructions of both wave velocity parameters (VP, VS and VP/VS) and earthquake hypocenter locations. The tomographic codes used for this work are SimulPS14 (a), TLR3 (b) and GAEA(c), which consider different approaches to resolve the inversion problem. We will test several one-dimensional (1D) velocity models as starting parameters for travel-time tomography. These models are obtained by applying both conventional linearized inversion algorithms (a, d) and fully nonlinear methods (e, f). The, velocity contrasts are detected by migrated at depth converted reflected/transmitted waves within the 3D tomographic model (g).

Once reconstructed the seismic structure, we will compare it with the rocks velocity gained from the analysis of commercial seismic lines (h), well logs and laboratory data (i). We will also test the possibility to usea starting 3D velocity model (obtained by combining balanced geological restoration models and seismic/sonic logs interval velocities) plus structural complexities, for tomographic inversions.

References

  1. Thurber, C. H. , 1993, Local earthquake tomography: velocities and Vp/Vs – theory,  in Seismic Tomography: Theory and Practice. H. M. Iyer and K. Hiahara, Eds., Chapman & Hall, London, UK.
  2. Latorre D., J. Virieux, T. Monfret, V. Monteiller, T. Vanorio, J.-L. Got, A new seismic tomography of Aigion area (Gulf of Corinth, Greece) from the 1991 data set. Geoph. J. Int. 159, 1013–1031.
  3. c.     Di Stefano, R., E. Kissling, C. Chiarabba, A. Amato, and D. Giardini, 2009, Shallow subduction beneath Italy: Three-dimensional images of the Adriatic-European-Tyrrhenian lithosphere system based on high-quality P wave arrival times, J. Geophys. Res., 114, B05305, doi:10.1029/2008JB005641.
  4. Kissling, E., W. L. Ellsworth, D. Eberarth-Phillips, and U. Kradolfer, 1994, Initial reference models in local earthquake tomography, J. Geophys. Res., 99, 635-464
  5. Herrero, A., A. Zollo, L. Improta, P. Dell’Aversana, S. Morandi, 2000, 2-D nonlinear travel time tomography by multi scale search; imaging an overthrust structure in Southern Apennines (Italy), Eos Trans. AGU, 81. 48.
  6. Lomax, A., J. Virieux, P. Volant and C. Berge, (2000), Probabilistic earthquake location in 3D and layered models: Introduction of a Metropolis-Gibbs method and comparison with linear locations, in Advances in Seismic Event Location, Thurber, C.H., and N. Rabinowitz (eds.), Kluwer, Amsterdam, 101-134.
  7. Latorre, D., A. Amato, and C. Chiarabba, 2010, High‐resolution seismic imaging of the Mw5.7, 2002 Molise, southern Italy, earthquake area: Evidence of deep fault reactivation, Tectonics, 29, TC4014, doi:10.1029/2009TC002595.
  8. Mirabella, F., F. Brozzetti, A. Lupattelli, and M. R. Barchi (2011), Tectonic evolution of a low-angle extensional fault system from restored cross-sections in the Northern Apennines (Italy), Tectonics, 30, TC6002, doi:10.1029/2011TC002890.
  9. Trippetta, F., C. Collettini, S. Vinciguerra, P.G. Meredith, 2010. Laboratory measurements of the physical properties of Triassic Evaporites from Central Italy and correlation with geophysical data, Tectonophysics 492, 121–132.