Class Outline I III IV V Deformation of

Class Outline I. III. IV. V. Deformation of the lithosphere, an overview Basic Techniques in Structural Geology and Tectonics Basic of Continuum mechanics- strain Basic of Continuum mechanics- stress Deformation Mechanism…

II. Basic Techniques in Structural Geology • • Fundamental principles Field measurements and mapping Stereographic projections … (See section H of Appendix of Davis&Raynolds, an/or P 45 -53 of Suppe)

Representations of lines and planes. . Plane as great circle. . Line as a pole. .

Stereographic equal-angle projection (Wulff’s Stereonet) Lambert’s equal area projection (Schmidt’s stereonet)

Spherical coordinate frame… Polar Net (N is the pole of the coordinate net)

Stereographic nets (equal-angle nets or Wulff’s stereonets) NB: Only half of the sphere is generally plotted Polar Net (polar axis vertical) Meridional Net (polar axis horizontal)

Equal-area nets- Schmidt Polar Net (polar axis vertical) Meridional Net (polar axis horizontal)

Projecting data… B(B’): 72, 0 (252, 0) C: 72, 45

B (B’): 72, 0 (252, 0) C: 72, 45 Q: 227, 43 (e. g. , dip direction of a bed S: 47, 47 (pole to bedding defined by Q)

Paper & pencil. . N 65, 20 SE

Measuring angles on a sterographic projection… P: 272, 45

Fold axis of (Cylindrical) fold might be determined from the intersection of bedding planes.

Folded bedding as poles & as great circles. . β diagram n(n-1)/2 intersections Π diagram

Elastic Rebound Theory Posterior to Last earthquake Interseismic strain (locked fault gets stressed) Co-seismic strain (fault failure during Earthquake

First Motions

P-wave Radiation Pattern

• Earthquake focal mechanisms will always have variations in polarity. Some stations will have first motion up, others first motion down.

First Motions: Denali Earthquake

Earthquake Focal Mechanisms

Earthquake Focal Mechanisms