Sciences and Teaching of Natural Systems

DANIELE CASALBORE
DANIELE CASALBORE

Developing competencesandlearning outcomes

Educational goals:
The student is provided the theoretical basis and the tools (also information) for the interpretation of the main geophysical methods for the study of the seabed. Are also treated the sampling methods and means for the acquisition of data at sea.
Learning ouctomes:
Knowledge of the principles for geophysical prospecting of marine geology
Knowledge of instrumentation and sampling techniques of the fund and subsoil
Ability to design campaigns for relief on the basis of scientific objectives
Knowledge of the principles of seismic data processing and sonar
Ability to interpret geophysical data and sampling of the seabed

The study of the seafloor is becoming increasingly important in the socio-economic development of several countries in relation to the growing exploitation of marine resources (abiotic and biotic), installation of coastal and marine infrastructures (primarily submarine cables), assessment of marine geo-risks (landslides and underwater volcanoes, earthquakes and associated tsunamis) and anthropic impacts (such as urban waste, microplastics, etc.) on marine ecosystems.
The general objective of the course is to provide knowledge both of seafloor investigation methods and data processing.

Skills to be developed and expected learning outcomes:
Knowledge of the principles for geophysical prospecting of marine geology
Knowledge of instrumentation and sampling techniques of the fund and subsoil
Ability to design campaigns for relief on the basis of scientific objectives
Knowledge of the principles of seismic data processing and sonar
Ability to interpret geophysical data and sampling of the seabed

Basic knowledge of geology, physics (optics and acoustics) physical oceanography and
marine chemistry

1. General part: marine research vessels, submarines, ROV and A.U.V. Range- range positioning systems, Loran, GPS,
DGPS.
2. Methods of direct sampling of the seafloor: Coring (gravity and vibration), grabs and box corer, drilling, non-destructive
analysis (sensor logging), opening and study of cores.
3. Geophysical methods in potential: magnetometric prospection, exploration gravimetric
4. Elastic waves: seismic rays and wave fronts; frequency, amplitude, wavelength; fourier transform and waveforms; volume
waves and surface seismic velocity, elastic module, P-wave velocity in different types of rock, reflection and refraction; snell's
law, the critical angle of refraction, and seismograms shot gather, recognition of different types of waves (direct, reflected,
refracted and ground- roll) in the shot gather.
5. Principles of seismic reflection: seismic 2D, 3D and pseudo 3D onshore and offshore; types of representation (wiggle,
variable area and density); acoustic impedance, reflection coefficient and transmission, seismic sections, and procedure of the
convolution theorem; analog/digital conversion (sampling interval, the Nyquist frequency, alliasing).
6. Mode of acquisition and processing of multi-channel seismic reflection: method of seismic surveys at sea, resonant and
impulsive seismic sources and hydrophones; pre-processing and post-stack demultiplexing, static corrections, muting, Mid
Point Common, Common Depth Point. CDP- CMP, shot, common offset gathers. Normal Move Out and equation of the
hyperbola NMO velocity analysis and semblance panels, mean square velocity and interval velocity (Dix equation). Stack,
post- stack processing (mono and multichannel seismic) frequency filtering and amplification for recovery of the amplitudes
(TVG, AGC). Spiking and predictive deconvolution, migration, ray-tracing. Resolution seismic vertical and horizontal Fresnel
zone.
7. Acoustic effects and distortions on seismic profiles: Vertical Exaggeration, direct wave, ringing, multiple reflections,
diffraction hyperbolas, pull- ups and push -down processing effects.
8. 3D seismic: Principles, methods of acquisition and interpretation, seismic 4D.
9. Side Scan Sonar: Principle of operation (diffraction, backscatter, emission lobes). Resolution sonograms (along track and
across track), the calculation of the height of the objects. Geometric processing (anamorphosis correction and slant - range).
Radiometric corrections (TVG and shading correction). Mosaicking of sonograms.
10 Multibeam (multibeam echo sounder): Principle of operation and the capture mode (positioning, attitude sensors, sensor
speed). Footprint, resolution, accuracy and precision. Data processing: calibration (application of the curve and speed of the
tide, calibration for pitch, roll, heave and time-delay), noise canceling (automatic filters, manual cleaning).

pdf del corso e articoli scientifici
E.J.W. Jones: Marine Geophysics, Wiley & Sons, Ltd.
Mussett Khan: Exploring the Underground, Freeman

The course includes 40 hours of lectures (5 CFU)integrated by 12 hours of practice (1 CFU).

In the lectures, the main indirect and direct methodologies for the investigation of the seafloor will be presented (28 hours) using the teaching material (powerpoint and pdf presentations) downloadable from the moodle Sapienza website. These lessons will be accompanied by collegial discussions of examples of marine survey planning and processing/interpretation of the acquired data (8 hours). In addition, 4 hours of lectures will be dedicated to the presentation by groups of students of specific topics covered in the course and explored in depth through the reading of scientific articles.

The exercises will be dedicated to the classroom processing of different types of marine data through the use of open-source or licensed software that will be installed on the students' laptops. In particular, 4 hours of processing will be dedicated to seismic data, 4 hours to sonar data (multibeam and side-scan sonar), 2 hours to sampling of the seabed and 2 hours to their integration.

There is also the possibility of participating in oceanographical cruises during the course or after it

4 hours per week divided in two days

The evaluation of the profit will be made by an oral examination designed to assess the knowledge
acquired during the course. During the oral examination will be interpreted geophysical data, to test the
ability of interpretation of the same.

how does the multibeam system work?
which are the direct investigations for the environmental characterization of the seafloor?
which is the difference between single- and multi-channels seismics?

• General part: 1  week
  • Books: slides


• Acoustic waves: 2 weeks
  • Books: slides


• Reflection seismic: 3 weeks
  • Books: slides and scientific papers


• active sonars: 3 weeks
  • Books: slides and scientific papers


• seafloor sampling and other methods: 2 weeks


• Geophysical
  methods in potential: 1 week