Earthquakes are powerful movements of Earth's lithosphere along faults or... Show more
Biology76 views·Updated May 20, 2026·2 pagesUnderstanding Earthquakes: A Study Guide
Ace@acesvale
1
of 2
Earthquake Basics and Types of Faults
An earthquake occurs when Earth's lithosphere (the crust and upper mantle) moves along a fault. Every earthquake has three main parts: the fault (the crack where movement happens), the focus (the underground starting point), and the epicenter (the point directly above the focus on Earth's surface).
Faults form when Earth's crust breaks or cracks, creating planes along which movement occurs. The rock above the fault plane is called the hanging wall, while the rock below is the footwall. How these walls move determines the type of fault: normal faults occur when the hanging wall moves downward (caused by divergent boundaries), reverse or thrust faults happen when the hanging wall moves upward (from convergent boundaries), and strike-slip faults involve horizontal movement (from transform boundaries).
Earthquakes can cause devastating effects including tsunamis (massive ocean waves from underwater quakes) and aftershocks (smaller tremors following the main earthquake). The Richter Magnitude scale measures earthquake strength—the higher the number, the more extensive the damage.
Remember This: The epicenter is not where the earthquake begins underground—that's the focus! The epicenter is the point on Earth's surface directly above the focus.
2
of 2
Seismic Waves
When an earthquake strikes, energy radiates from the focus in all directions as seismic waves. These waves come in two main categories: surface waves and body waves, each behaving differently as they travel.
Surface waves do the most damage during earthquakes. They include Raleigh waves and Love waves that travel along Earth's surface, shaking buildings and infrastructure. These are what you feel most strongly during a quake.
Body waves travel through Earth's interior and come in two types. P-waves (Primary waves) are the fastest, arriving first at seismic stations. They push and pull the ground like a Slinky and can travel through solids, liquids, and gases. S-waves (Secondary waves) are slower and arrive second. They move the ground side-to-side but cannot travel through liquids—an important fact that helps scientists study Earth's interior.
Cool Fact: Scientists can tell that Earth's outer core is liquid because S-waves disappear when they reach it, while P-waves continue through!
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Biology76 views·Updated May 20, 2026·2 pagesUnderstanding Earthquakes: A Study Guide
Ace@acesvale
Earthquakes are powerful movements of Earth's lithosphere along faults or cracks. Understanding how earthquakes work, their various components, and the waves they produce helps us better predict and prepare for these natural events.
1
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Earthquake Basics and Types of Faults
An earthquake occurs when Earth's lithosphere (the crust and upper mantle) moves along a fault. Every earthquake has three main parts: the fault (the crack where movement happens), the focus (the underground starting point), and the epicenter (the point directly above the focus on Earth's surface).
Faults form when Earth's crust breaks or cracks, creating planes along which movement occurs. The rock above the fault plane is called the hanging wall, while the rock below is the footwall. How these walls move determines the type of fault: normal faults occur when the hanging wall moves downward (caused by divergent boundaries), reverse or thrust faults happen when the hanging wall moves upward (from convergent boundaries), and strike-slip faults involve horizontal movement (from transform boundaries).
Earthquakes can cause devastating effects including tsunamis (massive ocean waves from underwater quakes) and aftershocks (smaller tremors following the main earthquake). The Richter Magnitude scale measures earthquake strength—the higher the number, the more extensive the damage.
Remember This: The epicenter is not where the earthquake begins underground—that's the focus! The epicenter is the point on Earth's surface directly above the focus.
2
of 2Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Seismic Waves
When an earthquake strikes, energy radiates from the focus in all directions as seismic waves. These waves come in two main categories: surface waves and body waves, each behaving differently as they travel.
Surface waves do the most damage during earthquakes. They include Raleigh waves and Love waves that travel along Earth's surface, shaking buildings and infrastructure. These are what you feel most strongly during a quake.
Body waves travel through Earth's interior and come in two types. P-waves (Primary waves) are the fastest, arriving first at seismic stations. They push and pull the ground like a Slinky and can travel through solids, liquids, and gases. S-waves (Secondary waves) are slower and arrive second. They move the ground side-to-side but cannot travel through liquids—an important fact that helps scientists study Earth's interior.
Cool Fact: Scientists can tell that Earth's outer core is liquid because S-waves disappear when they reach it, while P-waves continue through!
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What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
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You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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