Ch 8 Earthquakes Flashcards

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Questions and Answers

What is an earthquake?

An earthquake is the vibration of earth produced by the rapid release of energy.

What are the differences between the focus and epicenter of an earthquake?

Focus is the point of earthquake origin below earth's surface directly below the epicenter; epicenter is the point of earthquake origin on the earth's surface.

What does the Elastic Rebound Hypothesis state?

Earthquakes are produced by the rapid release of elastic energy stored in rocks within earth's lithosphere.

What are aftershocks?

Aftershocks are the movements that follow a major earthquake, often producing smaller earthquakes. Signup and view all the answers

What are foreshocks?

Foreshocks are small earthquakes that often occur before a major earthquake. Signup and view all the answers

What is a seismograph?

Seismographs are instruments that record earthquake waves. Signup and view all the answers

What is a seismogram?

Seismograms are the record made by a seismograph. Signup and view all the answers

What are the differences between body waves and surface waves?

Body waves travel through earth's interior, while surface waves travel along earth's outer layer. Signup and view all the answers

What are the properties of P waves, S waves, and surface waves?

P waves are the fastest, travel through solid, liquid, and gas; S waves only travel through solids and arrive second; surface waves are the slowest and most destructive. Signup and view all the answers

How can you find the exact location of an earthquake epicenter?

Draw a circle around each seismic station on a map, with radius equal to their distance from the epicenter; the intersection of the circles indicates the epicenter. Signup and view all the answers

What are the two scales used to measure earthquakes?

Richter scale and Moment Magnitude. Signup and view all the answers

What is a Richter scale?

It is outdated and only gives vague descriptions of effects felt at the epicenter. Signup and view all the answers

What is Moment Magnitude?

It is the most widely used scale and provides an accurate description of the effects felt near the epicenter. Signup and view all the answers

What are 3 factors that affect the designs of buildings in earthquake-prone areas?

<ol> <li>Nature of material structure built upon (soil, foundation) 2. Building design and materials used 3. Duration and intensity of vibrations.</li> </ol> Signup and view all the answers

What is liquefaction?

Liquefaction is when loosely consolidated sediments are saturated with water, causing land to turn into a liquid type material during moderate earthquakes. Signup and view all the answers

What is a tsunami?

A series of seismic sea waves produced from either an underwater landslide or the vertical displacement of the ocean floor during an earthquake. Signup and view all the answers

What are 3 types of dangers caused by earthquakes?

<ol> <li>Building/structure failure 2. Landslides 3. Fires 4. Ground subsidence 5. Basic services not available (power, water, gas).</li> </ol> Signup and view all the answers

Can scientists predict when earthquakes are going to occur?

False Signup and view all the answers

Study Notes

Earthquake Basics

An earthquake is the vibration of the earth caused by the rapid release of energy, typically due to slippage along a fault.
The focus is the origin point of an earthquake below the Earth's surface, while the epicenter is directly above it on the surface.

Faults

A fault is a crack or break in the Earth's crust where seismic activity occurs.

Elastic Rebound Hypothesis

Earthquakes occur when elastic energy stored in rocks is rapidly released upon reaching their breaking point.

Aftershocks and Foreshocks

Aftershocks are smaller earthquakes that follow a significant quake.
Foreshocks are minor quakes that occur before a major seismic event.

Seismographs and Seismograms

Seismographs are devices used to record earthquake waves.
Seismograms are the resulting records produced by seismographs.

Types of Seismic Waves

Body waves travel through the Earth's interior.
Surface waves travel along the Earth's outer layer.

Properties of Seismic Waves

P waves (Primary waves): Fastest, travel through solid, liquid, and gas.
S waves (Secondary waves): Slower, can only travel through solids.
Surface waves: Slowest and most destructive, travel along the surface.

Determining Epicenter Location

To locate an earthquake's epicenter, draw circles around three seismic stations based on their distance to the epicenter; the intersection point identifies the epicenter.

Earthquake Measurement Scales

Two scales are used to measure earthquakes: the Richter scale and the Moment Magnitude scale.
Moment Magnitude is more widely used due to its accuracy in describing effects near the epicenter.

Building Design Factors in Earthquake-Prone Areas

Key factors include the nature of the foundational soil, building materials and design, and the intensity and duration of vibrations.

Liquefaction

Liquefaction occurs when water-saturated sediments become unstable during an earthquake, potentially transforming solid ground into liquid, affecting populated areas.

Tsunami Formation

A tsunami is a series of waves caused by underwater landslides or the vertical displacement of the ocean floor during an earthquake, capable of traveling at 700 mph in the open sea before slowing and increasing in height as they approach shore.

Additional Earthquake Hazards

Earthquakes can cause structural failures, landslides, fires, ground subsidence, and disruption to essential services such as power and water.

Earthquake Prediction

Scientists cannot predict specific earthquakes but can make long-term estimates based on historical "seismic gaps" in areas previously prone to earthquakes.

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Description

Test your knowledge of earthquakes with these flashcards covering key concepts such as the definitions of earthquakes, the differences between the focus and epicenter, and faults. Ideal for students studying geology or earth sciences.