Faults

Faults

A fault is a break in Earth's crust where rocks move past each other due to tectonic forces. These movements can cause earthquakes, land shifts, and the formation of mountains and valleys. Faults are classified into three main types based on how the rocks move:

1. Normal Faults – Formed by tension (rocks pulling apart).
2. Reverse Faults – Formed by compression (rocks pushing together).
3. Strike-Slip Faults – Formed by shearing (rocks sliding past each other).

By studying different types of faults, scientists can learn more about how earthquakes happen, how plates shift, and how Earth’s surface is reshaped over time.

Science and Engineering Practices (SEP): Developing and Using Models

Scientists use models to study fault movements and predict earthquake activity. They analyze seismic data, GPS tracking, and satellite imaging to monitor how faults shift over time. 3D models and computer simulations help scientists understand how faults form, impact landscapes, and contribute to earthquakes.

Activity Ideas:

• Fault Block Simulation – Use three foam blocks or sponges to model normal, reverse, and strike-slip faults. Push, pull, or slide the blocks to demonstrate how tectonic forces cause different fault movements.
• Fault Type Sorting Challenge – Examine diagrams or photos of real-world faults and classify them as normal, reverse, or strike-slip. Use evidence from the image to explain what type of stress caused the fault.

Crosscutting Concepts (CCC): Cause and Effect

Faults form due to tectonic forces acting on Earth's crust.

• Cause: Tension pulls rocks apart.
  Effect: Normal faults form, creating valleys like the East African Rift Valley.
• Cause: Compression pushes rocks together.
  Effect: Reverse faults form, leading to mountain formation, such as the Himalayas.
• Cause: Shearing forces slide rocks past each other.
  Effect: Strike-slip faults form, triggering earthquakes like those along the San Andreas Fault in California.