GEOPHYSICAL METHODS OF EXPLORATION

42 hours (6 CFU) of frontal lessons

Should the teaching be delivered in a blended or distance learning mode, necessary variations from what has been stated above may be introduced in order to comply with the syllabus provided and given in the syllabus

Introduction 1: Geophysical methods and their applicability. Design of a geophysical campaign: target identification, selection of interval stations, disturbance.

Introduction 2: Differences between Field Geophysics and Geophysics of Urban Areas and related issues. Geophysical methodologies that can be used in urban areas for characterizing the properties of the soils present. Traditional and innovative geophysical methodologies. Invasive and non-invasive techniques, Fields of applicability, limitations and potential of the main geophysical methodologies that can be used in urban areas. 

Applied seismology: Seismic waves, reflection and transmission of incident rays, critical refraction, diffraction, intrinsic attenuation, spherical divergence, scattering, seismic sources, detection and recording of seismic waves.

Refraction seismic: Semispace and dromochrone of direct waves, horizontal layer and dromochrone of refracted waves, horizontal layers, inclined layer, non-planar refractors, survey, application cases.

Reflection Seismic: Horizontal layer and dromochrone of reflected waves, normal moveout, horizontal layers and rms velocity, multiple reflections, survey and horizontal-vertical resolution, data processing, application cases.

Other Seismic Methods: Cross-hole test, Down-hole test, MASW methodologies, H/V, Seismic Tomography, Refraction Microtremor analysis - ReMi, application cases.

Electrical Methods: The electrical resistivity of rocks, Archie's formula, Anisotropy, Longitudinal conductance, Transverse resistance, Principles of equivalence and suppression, Instrumentation, Energizing section, Receiving section, Signal acquisition in cases of low signal to noise ratio, Resistivity method, Current flow in a homogeneous medium: Theoretical fundamentals, Electrode devices, Resistivity profiles and surveys, The acquisition of data in the field, Data analysis and interpretation, The use of logarithmic scale, Direct and inverse interpretation, Superposition method, Auxiliary point method for the interpretation of curves with more than three layers, Auxiliary graphs, The use of computer for interpretation, Apparent resistivity maps, pseudosection, Reconstructing the impermeable conductive substrate for hydrogeological investigations, Choosing the most appropriate geoelectrical investigations for archaeological campaigns and engineering purposes, Electrical measurements in wells, Conventional electrical coring, Choosing the methodologies to be used in the campaign for optimizing investigations, 2D and 3D electrical tomography, Application cases.

Seismic Hazard and Local Seismic Response: Seismic Risk and Seismic Hazard, Building Vulnerability, Seismic Hazard Assessment: deterministic approach, probabilistic approach, Probabilistic Hazard Estimation, Design Earthquake Evaluation Criteria, Seismic Microzonation, Hazard Scenarios, Local Geology and Ground Condition Assessment, Effects due to Heterogeneity, Presence of Geometric and Topographic Irregularities, Presence of Tectonic Structures and Cavities, Local Seismic Response: Response spectrum, Calculation of local seismic response, Structuring a local seismic response study by numerical modeling, Microtremors, Nakamura Technique, Spectral ratios (HVSR, H/Href), Modeling, Examples of macro and micro seismic zoning. 

G.   Lanzo, F. Silvestri (1999). RISPOSTA SISMICA LOCALE. Argomenti di Ingegneria Geotecnica 10, Edizioni Hevelius.

2.     C. Mancuso (1996). MISURE DINAMICHE IN SITO. Argomenti di Ingegneria Geotecnica 4, Edizioni Heveliu   

M.  Corrao e G. Coco (2021). Geofisica applicata. Con particolare riferimento alle prospezioni sismiche, elettriche, elettromagnetiche e geotermiche. Flaccovio Dario editore.

  L. Nori, P. Di Marcantonio (2014). Manuale pratico di risposta sismica locale. Dal sismogramma allo spettro di progetto con Rexel e Strata.

Di   dispense .

1. What are the similarities and differences between different seismic exploration methods?
2. On what does the maximum depth that can be investigated with a geophysical profile depend?
3. Outline the main steps of data processing in a reflection seismic survey.
4. Geoelectrical characterization of the subsurface using 2D sections.
5. Impedance contrast sections
6. Explain what the MASW and ReMi techniques consist of
7. Describe the different steps for assessing local seismic response..