Exploration Geology

Fracture and crack mechanics (dislocation model for stress and slip). Dislocation model for stress and slip. Stress transformations. Friction: Da Vinci, Amontons, Coulomb, Rabinowicz-Tabor-Bowden (1950’s). Mohr circles and the optimum angle of failure. Adhesive theory of friction (Contact junction size, friction as the ratio of material hardness and shear strength, concepts of static & dynamic friction, critical friction distance, contact age, velocity weakening friction and contact size, contact aging or frictional healing, frictional state-contact age). Mechanics of frictional sliding: stick-slip. Discussion on Rabinowicz paper. Rate & State Friction constitutive laws part A and B. Refresh on Python. Rate & State Friction constitutive laws part C and D Work on faulting Visit Sapienza rock deformation and earthquake physics lab & spring slider. Fault rocks, deformation processes and fault structure. What is the shear stress, or differential stress, required to make a crustal fault move? What is the fault slip behavior (seismic vs. aseismic) upon reactivation? Fault and permeability Induced and triggered seismicity from the geo-energy activities (wastewater disposals, enhanced oil recovery, EOR, fracking, carbon capture and storage, CCS, enhanced geothermal systems (EGS), reservoir depletion): examples worldwide. Rock deformation experiments for improving our understanding of induced seismicity. Visit Sapienza rock deformation and earthquake physics lab: what we measure in the lab and how. Python on laboratory experiments on friction. Python plotting earthquakes of the Amatrice-Visso-Norcia sequence (4h). Rock and fault rheology to explain the seismicity of Amatrice-Visso-Norcia part A Rock and fault rheology to explain the seismicity of Amatrice-Visso-Norcia part B The mechanics of slow slip part A The mechanics of slow slip part B

Units of measure and conversions. Stress and strain and Hook’s law. Basic trigonometry, linear and exponential functions. Geophysical constraints for the Earth’s interior, stress ellipsoid and its principal axis, heat flow.

C.H. Scholz, The mechanics of earthquakes and faulting: Cambridge, third edition. PDF slides that can be downloaded via Moodle.

Aula (Lezioni frontali): 32 ore Laboratori/Esercitazioni: 24 ore

The course is in English, and the English has to be considered as one more learning opportunity

Presentation (.ppt type) of a scientific paper presented during the course. Several questions on the topics of the course. Data plot and analysis via Python.

See the detailed list presented in the course slides.

Aula (Lezioni frontali): 32 ore Laboratori/Esercitazioni: 24 ore

Introduction. Theory 1) Laboratory experiments to introduce/refresh the concepts of: stress, lithostatic load, elasto-frictional & viscous rheology, earthquake dynamics in the lab. 2) Friction, Faulting and Earthquake Fault Slip: From Bowden/Tabor and Rabinowicz to Leeman et al., 2016. Rate and state friction laws. 3) Fault structure, associated frictional properties and fault slip behaviour, seismic vs. aseismic. 4) Faults & permeability. Fluid involvement in seismic activity: examples from the lab scale, up to the 100s-km scale. Practical part: 1) Lab on spring-slider. 2) Lab on devices to measure force, displacement, strain. 3) Lab experiment on friction. 4) Lab experiment on permeability. 5) Data acquisition, manipulation and visualization via Python: a) Rheological profiles. b) Data plot and analysis on friction. c) Data plot and analysis on permeability.

C.H. Scholz, The mechanics of earthquakes and faulting: Cambridge, third edition. PDF slides that can be downloaded via Moodle.

Oral presentation of a study of rock mechanics. Oral exam.