GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 3.2 675 SRT map (Fig. 3f) shows some differences: it individuates the presence of the first layer, with velocities in the range of 300-600m/s, and of a second layer, with higher velocity, between 700 and 900m/s, as in the separated inversion, but since the maximum reached value is 950m/s, the travertinous area seems not to be individuated. However, the significant maps for the joint inversion, as the map of the cross-gradients function and the scatter plot, show the good results obtained. The map of the cross-gradients function (Fig. 3g) shows a remarkable reduction, meaning that the two models have a better structural similarity than the separated inversion and the scatter-plot (Fig. 3h) highlights a reduced data dispersion, even if it is not possible to define more defined sublayering probably because of the errors in data. In conclusion, the joint inversion is capable, through the cross-gradient operator, of improving the consistency between the two different models without the need to use a specific relationship between the resistivity and seismic velocity, reducing the ambiguities in the interpretation of the joint inversion subsoil model. References Cercato M. and G. De Donno; 2018: Focusing on soil-foundation heterogeneity through high-resolution electrical and seismic tomography . Near Surface Geophysics 16 (1), 1-12 Demirci I.˙, Candansayar M.E., Vafidis A.., Soupios P.; 2017: Two dimensional joint inversion of direct current resistivity, radio-magnetotelluric and seismic refraction data: an application from Bafra Plain , Turkey . J Appl Geophys 139:316–330. Doetsch J., Linde N., Coscia I., Greenhalgh S. A., and Green A. G.; 2010: Zonation for 3D aquifer characterization based on joint inversions of multimethod crosshole geophysical data. Geophysics, 75, no. 6, G53–G64,doi: 10.1190/1.3496476. Gallardo L. A., and Meju M. A..; 2004: Joint two-dimensional DC resistivity and seismic travel time inversion with cross gradients constraints . J. Geophys. Res., 109, B03311, doi:10.1029/2003JB002716. Günther T.; 2004: Inversion Methods and Resolution Analysis for the 2D/3D Reconstruction of Resistivity Structures from DC Measurements , PhD thesis, Freiberg University of Mining and Technology. Linde N., Binley A., Tryggvason A., Pedersen L. B., and Revil A.; 2006: Improved hydrogeophysical characterization using joint inversion of cross-hole electrical resistance and ground-penetrating radar traveltime data . Water Resour. Res., 42, W12404, doi:10.1029/2006WR005131. Linde N. and Doetsch J.; 2016: Joint inversion in hydrogeophysics and near-surface geophysics. In: Integrated imaging of the Earth, M. Moorkamp, P. Lelievre, N. Linde, and A. Khan (Editors), ch.7, 119-135, John Wiley & Sons, Inc. Hoboken, New Jersey. Doi: 10.1002/9781118929063.ch7. Moorkamp M.; 2017: Integrating electromagnetic data with other geophysical observations for enhanced imaging of the earth: a tutorial and review . SurvGeophys. doi:10.1007/s10712-017-9413-7. Rücker C.; 2011: Advanced Electrical Resistivity Modelling and Inversion using Unstructured Discretization . PhD thesis, University of Leipzig Rücker C., Günther, T., Wagner, F.M.; 2017: pyGIMLi: An open-source library for modelling and inversion in geophysics . Computers and Geosciences, 109, 106-123, doi: 10.1016/j.cageo.2017.07.011. Sethian J.A.; 1999: Fast marching methods . SIAMRev., Vol. 41,No. 2, pp. 199–235. Zhdanov M.S.; 2015: Inverse Theory and Applications in Geophysics , Elsevier Published.