earthquakes. learning targets. i can: define stress and strain as they apply to rocks. forces within...
TRANSCRIPT
![Page 1: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/1.jpg)
Earthquakes
![Page 2: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/2.jpg)
Learning Targets. I can:• Define stress and strain as they apply to rocks.
Forces Within Earth
• Distinguish among the three types of faults.• Contrast three types of seismic waves.
– stress
– strain
– fault
– primary wave
Vocabulary– secondary wave
– surface wave
– focus
– epicenter
![Page 3: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/3.jpg)
I. Forces Within Earth
Forces Within Earth
A. Stress – pressure that breaks rock. It is the Force per unit Area
1. Compression
2. Tension
3. Shear
![Page 4: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/4.jpg)
Forces Within Earth
– Compression is stress that decreases
the volume of a material.
– Tension is stress that pulls a
material apart.
– Shear is stress that causes a material to twist.
![Page 5: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/5.jpg)
B. Strain – how the rock responds to stresses.
C. Deformation of rock
1. Elastic deformation; rock can bounce back
2. Ductile deformation; permanent
3. Failure; rock breaks. This is called a fault
Forces Within Earth
![Page 6: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/6.jpg)
Stress and Strain• There is a distinct relationship between stress and
strain that can be plotted as a stress-strain curve.
Forces Within Earth
– A stress-strain curve usually has two segments: a straight segment and a curved segment.
– Low stresses produce the straight segment, which represents the elastic strain of a material.
– If the elastic strain is reduced to zero, the deformation disappears.
![Page 7: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/7.jpg)
Stress and Strain
Ductile Deformation
Forces Within Earth
– When stress exceeds a certain value, a material undergoes deformation, shown by the curved segment of the graph.
– This type of strain produces permanent deformation, which means that the material stays deformed even if the stress is reduced to zero.
![Page 8: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/8.jpg)
Forces Within Earth
D. Faults
1. Reverse fault – result of compression forces
2. Normal fault – result of tensional forces
3. Strike-slip fault – result of shear forces
![Page 9: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/9.jpg)
Earthquake Waves• Most earthquakes are caused by movements
along faults.
Forces Within Earth
• Irregular surfaces in rocks can snag and lock, causing stress to build in the rocks.
• When the rocks reach their elastic limit they break, and this produces an earthquake.
![Page 10: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/10.jpg)
E. Types of Seismic (Earthquake) Waves
Forces Within Earth
1. Primary waves, or P-waves, squeeze and pull rocks in the same direction the waves are traveling. Fastest seismic waves.
![Page 11: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/11.jpg)
Forces Within Earth
3. Surface waves travel along Earth’s surface, moving in two directions as they pass through rock.
2. Secondary waves, or S-waves, cause rocks to move at right angles to the direction of the waves. Travel at ½ the speed of P-waves. Do not travel through liquids.
Wave Simulator
![Page 12: Earthquakes. Learning Targets. I can: Define stress and strain as they apply to rocks. Forces Within Earth Distinguish among the three types of faults](https://reader036.vdocuments.site/reader036/viewer/2022062517/56649f315503460f94c4d561/html5/thumbnails/12.jpg)
Forces Within Earth
– P-waves and S-waves, also called body waves, pass through Earth’s interior.
– The focus is the point underground where the rock actually breaks
– The epicenter of an earthquake is on Earth’s surface directly above the focus.