الفهرس 
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Abstract
ABSTRACT
The purpose of the present thesis is mainly devoted to study the multidimensional smoothed and layered inversion, which is applied on DC-resistivity and
shallow seismic refraction data at the new Ras Gharib city.
In applied geophysics, the data as a result of the earth are measured. This is
what might be called a ’forward problem’: a model is given and the data are
calculated. The forward (or direct) problem is always uniquely solvable. It is often
the other way around: data have been measured and we wish to derive a plausible
(smoothed or layered) earth model that is consistent with the data, what may be
described as ’inverse problem’. ’Inversion theory’ is concerned with the problem of
making physical interfaces (i.e. layer boundaries) from the measured data. That study
introduces a theoretical background about those theories in details at chapter 2.
That study is concerned with applying the inversion theory at the electrical
resistivity data which is represented by 1-D ’VES’ and 2-D ’Wenner profiles’ data. It
aims at this part to produce the ’smoothed models’ that obtain the gradation of the
electrical resistivity, and the ’layered models’ that illustrate the real geologic layers
with those thicknesses and resistivities, It is found to be five layers and reached to
depth nearly 250 m. The other important item in this research is studying the
sensitivity of the models that expresses those realities.
Also this work is applied on shallow seismic refraction data, so a primary
conventional study of the depth determination and velocity calculations are applied
on the three measured profiles, it is found to be three layers and reached to a depth
nearly 40 m. Then other advanced study is applied by assuming that the third layer is
subjected to the ’diving wave’ theory.
The seismic tomography is the extra advanced method to imagine the
subsurface models by applying the inversion theory; it is the most accurate and
realistic interpretation method in making physical interfaces with known primary
velocities through an iterative procedure to produce ’smoothed models’ and ’layered
models’ for the three measured profiles. That method also supports with many
developed models as relative sensitivity, velocity gradient, quality parameter and
depth of investigation “DOI” index. As the previous calculations aim to model the
primary velocities, multichannel analysis of surface waves-active source “MASW” is
applied to obtain 1-D shear wave velocity profiles (2-D visualized sections).
Finally, an engineering-geological characterization is calculated for the three
measured profiles, and the soil type is determined through the referenced ranges
tables.
It can be concluded that the ’inversion theory’ has a wide application range in
the geophysical methods due to its accuracy, ability in modeling and minimizing the
RMS error % between the calculated data and the inverted models.