Earthquake Science: Fault Types and Mechanisms

Study Notes

Earthquake Causes and Mechanisms

Earthquakes result from the shifting and colliding of Earth's tectonic plates, leading to a sudden release of energy.
This energy travels as seismic waves, which cause ground shaking and potential damage to structures.
Faults are fractures in the Earth's crust where movement occurs, serving as the origin points for earthquakes.
Fault movements can be horizontal, vertical, or a combination, depending on the type of fault involved.

Types of Faults

Normal Faults:
- Characterized by the hanging wall moving downward relative to the footwall.
- Associated with areas of crustal extension where the Earth's crust is being pulled apart.
Reverse Faults:
- Defined by the hanging wall moving upward relative to the footwall.
- Connected to areas of compression where the Earth's crust is being pushed together.
Strike-Slip Faults:
- Involves horizontal movement of rocks on either side of the fault.
- Related to shearing forces that twist or slide the crust sideways.

Earthquake Dynamics

The interaction between tectonic plates and faults is the primary driver of earthquake occurrences.
When pressure builds between tectonic plates and exceeds the rock's strength, it results in a rupture along a fault.
The rupture initiates at a focus (hypocenter) beneath the Earth's surface, with the corresponding point on the surface being the epicenter.

Measuring Earthquakes

The magnitude of an earthquake is assessed using the Richter scale, which is logarithmic.
Each whole number increase on the Richter scale corresponds to a tenfold increase in the seismic wave amplitude.
A whole number increase also reflects approximately a 32-fold increase in the energy released by the earthquake.

Impact and Preparedness

Earthquakes are natural phenomena known for their potential to cause significant destruction.
While prevention of earthquakes is impossible, enhancing understanding of their causes enables better preparedness and mitigation of their impacts.

Description

Explore the fundamental concepts of earthquakes, focusing on the movement of tectonic plates and the resulting seismic activity. This quiz covers the types of faults and how they contribute to the occurrence of earthquakes in various geological settings.