Marone                   Geosc 508  (3.0 credits)                      Spring Term, 2007

Mechanics of Earthquakes and Faulting

 

Lectures: W F 8:30A – 9:45A            541 Deike Building

 

Tentative Syllabus (see www.geosc.psu.edu/Courses/Geosc508/)

Week

Topic

Reading

(Chap. in Scholz)

1.

Brittle Fracture I.  Milestones in continuum mechanics, concepts of modulus and stiffness. Stress-strain relations, elasticity, surface and body forces, tensors, Mohr circles.  Theoretical strength of materials, Defects, Stress concentrations, Griffith failure criteria, fracture mechanics.  Fracture toughness, Surface energy and Fracture energy. Cohesive zone, strain energy and the work of faulting. Macroscopic failure laws.  Coulomb-Mohr criteria and stress-states.

Ch. 1

2.

Brittle Fracture II. The strength of rocks.  Experimental data.  Pore fluid effects. Effective stress laws.  Dilatancy hardening.  The role of stiffness.  Strain rate dependence of rock strength. Brittle vs. Ductile deformation, Dilatancy, Schizosphere, Plastosphere,

Ch. 1

3.

Rock Friction I.  Amontonıs laws.  Concepts of static and kinetic friction. Bowden and Taborıs theory of friction. Asperities, adhesion, abrasion, wear.  Stick-slip and stability of frictional sliding.  Time dependent and memory effects. Fault re-strengthening and healing.

Ch. 2

4.

Rock Friction II.  Slip rate dependence of kinetic friction. Critical slip distance of friction, Rabinowiczıs experiments. Rate and state friction constitutive laws.  Elastic coupling and solution of history-dependent equations.  Forward models of velocity-step tests and frictional healing.

Ch. 2

5.

Fault Mechanics. Andersonian Faulting.  Hubbert-Rubey theory. State of stress in the crust.  Shear heating. Fault growth.

Ch. 3

6.

Fault Rocks and Fault Strength. Faulting in nature.  Fault rocks and fault zone thickness.  Wear in natural fault zones. Fault zone rheology.  Depth variation of fault rocks and structures.  Fault zone fabrics.  Fault zone heterogeneity.

Ch. 3

7.

Earthquake Mechanics.  Magnitude, seismic moment, quantification of earthquakes. Focal mechanisms, Source parameters.  Particle velocity, rupture velocity.  Seismic stress drop: static and dynamic. Seismic efficiency. Seismic spectra and interpretation.  Rise time, rupture duration.

Ch. 4

8.

Earthquake rupture nucleation.  Friction and fracture mechanics approach to nucleation.  The critical slip distance for seismic faulting.  Critical rupture patch size.  The transition from quasistatic to dynamic rupture.  Laboratory data.  Seismic data.

Ch. 4

9.

The seismic cycle.  Repeating earthquakes.  Rupture characteristics, time dependence.  Relation to laboratory-derived constitutive laws.

Ch. 5

10.

Earthquake scaling laws. fmax, fc.   Frequency dependence of seismic moment.  Strong motion data.  f -w models and interpretation.

Ch. 5

11.

Seismotectonics. Fault rheology from seismic studies.  Depth-frequency relations for seismicity.  Strong motion studies.  Earthquake afterslip and the relation between coseismic and postseismic slip.   Fault heterogeneity, slip heterogeneity.

Ch. 6

12. 

Earthquake Prediction.  Earthquake triggering and fault interaction. Precursory phenomena.  Historical observations. 

Ch. 7

13.

Rock Friction III.  Processes and mechanisms of friction, complex behavior, strain rate dependence, slip history effects, normal stress effects.  Forward models and constitutive laws for friction

Ch. 2