Elastic Behaviors = E eStrain, e, is linearly proportional to stress E = elasticity or Youngs modulusRock values of E are generally in GPa
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Chart1
10.5211
214
31.56
428
52.510
6312
73.514
8416
94.518
10520
115.522
12624
136.526
14728
157.530
16832
178.534
18936
199.538
201040
Case1
Case2
Case3
Strain
Stress
Elastic Behavior
Sheet1
CaseStressstress changeStrainstress changeElasticityViscosity
11111
12121
13131
14141
15151
16161
17171
18181
19191
1101101
1111111
1121121
1131131
1141141
1151151
1161161
1171171
1181181
1191191
1201201
2110.50.5
2211.00.5
2311.50.5
2412.00.5
2512.50.5
2613.00.5
2713.50.5
2814.00.5
2914.50.5
21015.00.5
21115.50.5
21216.00.5
21316.50.5
21417.00.5
21517.50.5
21618.00.5
21718.50.5
21819.00.5
21919.50.5
220110.00.5
3112.02
3214.02
3316.02
3418.02
35110.02
36112.02
37114.02
38116.02
39118.02
310120.02
311122.02
312124.02
313126.02
314128.02
315130.02
316132.02
317134.02
318136.02
319138.02
320140.02
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Sheet2
Sheet3
CaseStressstress changeStrainstress change
111112110.53112.02
121212211.03214.02
131312311.53316.02
141412412.03418.02
151512512.535110.02
161612613.036112.02
171712713.537114.02
181812814.038116.02
191912914.539118.02
110110121015.0310120.02
111111121115.5311122.02
112112121216.0312124.02
113113121316.5313126.02
114114121417.0314128.02
115115121517.5315130.02
116116121618.0316132.02
117117121718.5317134.02
118118121819.0318136.02
119119121919.5319138.02
1201201220110.0320140.02
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Case1
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Case3
Strain
Stress
Elastic Behavior
VISCOUS BEHAVIORContinuous flow at constant stressLinear, or Newtonian, viscous behavior is expressed as:e = (s*t)/visc, where visc = viscosityTypical viscosities for rocks are between 1020 to 1028 Poise. 1 Poise = 1 Pa*secViscous flow occurs in the solid earth below melting temperaturesRate is extremely slow and requires 106 yrs or moreTypical strain rates, e/t = 10-7/sec to 10-14/sec
Chart4
10.5211
214
31.56
428
52.510
6312
73.514
8416
94.518
10520
115.522
12624
136.526
14728
157.530
16832
178.534
18936
199.538
201040
Case1
Case2
Case3
Strain Rate, %/sec
Stress
Viscous
Sheet1
CaseStressstress changeStrainstress changeElasticityViscosity
11111
12121
13131
14141
15151
16161
17171
18181
19191
1101101
1111111
1121121
1131131
1141141
1151151
1161161
1171171
1181181
1191191
1201201
2110.50.5
2211.00.5
2311.50.5
2412.00.5
2512.50.5
2613.00.5
2713.50.5
2814.00.5
2914.50.5
21015.00.5
21115.50.5
21216.00.5
21316.50.5
21417.00.5
21517.50.5
21618.00.5
21718.50.5
21819.00.5
21919.50.5
220110.00.5
3112.02
3214.02
3316.02
3418.02
35110.02
36112.02
37114.02
38116.02
39118.02
310120.02
311122.02
312124.02
313126.02
314128.02
315130.02
316132.02
317134.02
318136.02
319138.02
320140.02
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Sheet1
Sheet2
Sheet3
CaseStressstress changeStrainstress change
111112110.53112.02
121212211.03214.02
131312311.53316.02
141412412.03418.02
151512512.535110.02
161612613.036112.02
171712713.537114.02
181812814.038116.02
191912914.539118.02
110110121015.0310120.02
111111121115.5311122.02
112112121216.0312124.02
113113121316.5313126.02
114114121417.0314128.02
115115121517.5315130.02
116116121618.0316132.02
117117121718.5317134.02
118118121819.0318136.02
119119121919.5319138.02
1201201220110.0320140.02
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Case1
Case2
Case3
Strain
Stress
Elastic Behavior
11
Case1
Case2
Case3
Strain Rate, %/sec
Stress
Viscous
SubstanceViscosity (Pa s)
Air (at 18 oC)1.9 x 10-5 (0.000019)Water (at 20 oC)1 x 10-3 (0.001)Canola Oil at room temp.0.1Motor Oil at room temp.1Corn syrup at room temp.8Pahoehoe lava100 to 1,000A'a lava1000 to 10,000Andesite lava106 to 107Rhyolite lava1011 to 1012
Table 1: Viscosity of Selected Fluids and Materials
*Viscosity is often given in units of Poise; 10 Poise = 1 Pa-s.
Poissons RatioPoissons Ratio, n = etransverse/elongitudinal In uniaxial tension, an incompressible material should have a n = 0.5Most rocks have n values of 0.25 0.35
FRACTURES AND FAULTS
STRENGTH and DUCTILITYStrength= max stress before failure
Ductility = max strain before failure
FRACTURES IN ROCKSIn uniaxial compression only extension fractures form. They always form parallel to the maximum compressive stress (mcs) and perpendicular to the least compressive stress ( which may also be a tensile stress)
Shear fractures form in biaxial and triaxial casesShear fractures form at acute angles to the mcsThe extension fractures form the acute bisectorShear fractures dominate over extension fractures in terms of frequencyFaults are big shear fractures (slip amounts > 1 m)
BRITTLE BEHAVIORNotice how tiny cracks form early on before the visible crack occurs
When there isonly one stressdirection, onlyextension fracturesform
In biaxial and triaxialcases, shear fracturesdominate
FAULTS (LARGE-SCALE SHEAR FRACTURES) FORM MAINLY AT PLATE BOUNDARIES
DIVERGENT PLATE BOUNDARYRED SEA AND SINAI PENINSULA
TRANSFORM PLATE BOUNDARY, CALIFORNIA
CONVERGENT PLATE BOUNDARY:Andean Type
CONVERGENT PLATE BOUNDARY: ALASKASeismicity and Wadati-Benioff Zone
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