Earth-printshttps://www.earth-prints.orgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Thu, 27 Jan 2022 04:34:56 GMT2022-01-27T04:34:56Z5011Parallel ‘large’ dense matrix problems: application to 3D joint inversion of seismological and gravity datahttp://hdl.handle.net/2122/8028Title: Parallel ‘large’ dense matrix problems: application to 3D joint inversion of seismological and gravity data
Authors: Tondi, R.; Cavazzoni, C.; Danecek, P.; Morelli, A.
Abstract: To obtain accurate and reliable estimations of the major lithological properties of the rock within a
studied volume, geophysics uses the joint information provided by different geophysical datasets
(e.g. gravimetric, magnetic, seismic). Representation of the different types of information entering the
problem using probability density functions can provide the mathematical framework to formulate
their combination. The maximum likelihood estimator of the resulting joint posterior probability
density functions leads to the solution of the problem. However, one key problem appears to limit the
use of this solver to an extensive range of real applications: information coming from potential fields
that implies the presence of dense matrices in the resolving estimator. It is well known that dense
matrix systems rapidly challenge both the algorithms and the computing platforms, and are not suited
to high-resolution 3D geophysical analysis. In this study, we propose a procedure that allows us to
obtain fast and reliable solutions of the joint posterior probability density functions in the presence of
large gravity datasets and using sophisticated model parametrization. As it is particularly CPUconsuming,
this 3D problem makes use of parallel computing to improve the performance and the
accuracy of the simulations. Analysis of the correctness of the results, and the performance on different
parallel environments, shows the portability and the efficiency of the code. This code is applied to a real
experiment, where we succeed in recovering a 3D shear-wave velocity and density distribution within
the upper mantle of the European continent, satisfying both the seismological and gravity data. On a
multiprocessor machine, we have been able to handle forward and inverse calculations with a dense
matrix of 215.66 Gb in 18 min, 20 s and 20 min, 54 s, respectively.
Thu, 01 Nov 2012 00:00:00 GMThttp://hdl.handle.net/2122/80282012-11-01T00:00:00Z