GEOPHYSICAL METHODS OF EXPLORATION

The main objective of this course is to provide students the ability to process and use geophysical data in order to be able to extract information of the subsurface.
The main knowledge gained will be:
- basic elements of gravimetric methods;
- basic elements of geomagnetic methods;
- basic elements of seismic methods;
- basic elements of electromagnetic methods;

- basic elements of evaluation of local seismic response.

The main ability gained will be:
- ability to plan a geophysical survey;
- ability to understand and interpret gravimetric anomaly;
- ability to understand and interpret geomagnetic anomaly;
- ability to process seismic data acquired by refraction and reflection methods and relative interpretation;
- ability to process electromagnetic data and relative interpretation;

- ability to avaluate the local seismic response.

Face to face, pratical training.

Introduction1: Geophysical methods and applications. Planning of a geophysical survey: identification of the target, choice of station interval, noise.

Introduction2: Data analysis: analog-digital conversion, spectral analysis, convolution, deconvolution, correlation, filtering.

Gravimetric method: physical principles, measurements of gravity, corrections to gravity measurements, Bouguer anomaly, methods of interpretation (field regional and residual anomalies due to bodies with different geometries, determination of depth and mass), applications and case histories.

Geomagnetic method: physical principles and units of geomagnetism, magnetic properties of rocks, susceptibility of rocks and minerals, Earth's magnetic field (components of the Earth's magnetic field, temporal variations of the field), magnetic instruments, magnetic survey, qualitative interpretation, quantitative Interpretation (anomalies due to bodies with different geometries, determination of depth), applications and case histories.

Seismology: seismic waves, reflection and transmission of incident rays, critical refraction, diffraction, intrinsic attenuation, spherical divergence, scattering, seismic sources, identification and registration of seismic waves.

Seismic refraction: halfspace and direct wave equation, horizontal layer and refracted wave equation, horizontal layers, inclined layer, non-planar discontinuities, survey, case histories.

Seismic reflection: horizontal layer and reflected wave equation, normal moveout, horizontal layers and rms velocity, multiple reflections, survey and horizontal-vertical resolution, data processing, case histories.

Surface waves analysis: dispersion curves, phase velocity, group velocity, active methods (MASW), passive methods (ReMi, ESAC, HVSR).

Ground Penetrating Radar: physical principles, dielectric properties of the material, acquisition of data, data analysis, interpretative techniques, applications and case histories.

Local seismic response: response spectrum, computation of the local seismic response, planning of a study of local seismic response by numerical modelling.

• An Introduction to Applied and Environmental Geophysics (Second Edition), J.M. Reynolds, Wiley-Blackwell Editore, 2011.
• Fundamentals of Geophysics, William Lowrie, 2011.
• An Introduction to Geophysical Exploration, P. Kearey et al., Blackwell Editore, 2002.
• Surface wave analysis for near surface applications. Giancarlo Dal Moro.
• Manuale pratico di risposta sismica locale. Dal sismogramma allo spettro di progetto con Rexel e Strata.
• Lecture notes.