Earth Science Chapter 8 Definitions Flashcards

Questions and Answers

What is an earthquake?

A sudden release of energy causing vibrations in the Earth (correct)

A type of volcanic eruption

A weather phenomenon

A large tsunami

What is the focus of an earthquake?

The point within Earth where an earthquake originates.

What are faults?

A fracture in Earth along which movement has occurred.

Explain elastic rebound in the context of earthquakes.

When rocks are deformed, they break, releasing the stored energy that results in the vibrations of an earthquake. Signup and view all the answers

What is an aftershock?

A small earthquake that follows the main earthquake. Signup and view all the answers

What is a foreshock?

A small earthquake that often precedes a major earthquake. Signup and view all the answers

What is fault creep?

Displacement along a fault that is so slow and gradual that little seismic activity occurs. Signup and view all the answers

Define seismology.

The study of earthquakes and seismic waves. Signup and view all the answers

What is a seismograph?

An instrument that records earthquake waves. Signup and view all the answers

Explain what a seismogram is.

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

What are surface waves?

A seismic wave that travels along the surface of Earth. Signup and view all the answers

What are body waves?

Seismic waves that travel through Earth's interior. Signup and view all the answers

What are Primary (P) waves?

Earthquake waves that push and pull rocks in the direction of the wave Signup and view all the answers

What are Secondary (S) waves?

Both A and C Signup and view all the answers

What is the epicenter of an earthquake?

The location on Earth's surface directly above the focus of an earthquake. Signup and view all the answers

What is the Circum-Pacific Belt?

Location where most earthquakes occur. Signup and view all the answers

Define intensity in the context of earthquakes.

Measure of the degree of shaking at a given locale based on the amount of damage. Signup and view all the answers

What does magnitude mean in terms of earthquakes?

Total amount of energy released during an earthquake. Signup and view all the answers

Explain the Modified Mercalli Intensity Scale.

Measures the amount of shaking and damage, can rate different amounts at different locations. Signup and view all the answers

What is the Richter scale?

A logarithmic scale of 1 to 10 used to express the energy released by an earthquake. Signup and view all the answers

What is the Moment Magnitude Scale?

A more precise measure of earthquake magnitude than the Richter scale. Signup and view all the answers

What is liquefaction?

A process in which the shaking of ground causes loose, wet soil to act like a liquid. Signup and view all the answers

What are seismic sea waves (tsunami)?

A water wave caused by an earthquake, volcanic eruption, or landslide. Signup and view all the answers

What is the crust of the Earth?

Earth's very thin outer layer. Signup and view all the answers

Define the mantle.

The rocky layer of Earth located beneath the crust and having a thickness of 2900 kilometers. Signup and view all the answers

What is the lithosphere?

Cool rigid layer of Earth, which includes the entire crust as well as the uppermost mantle. Signup and view all the answers

What is the asthenosphere?

The soft layer of the mantle on which pieces of the lithosphere move. Signup and view all the answers

What is the lower mantle?

Rigid, hard, and brittle, makes up 80% of the Earth's material. Signup and view all the answers

What is the core of the Earth?

Center of Earth composed of nickel and iron. Signup and view all the answers

What is the outer core?

Layer of the interior that exhibits the characteristics of a mobile liquid composed of iron and nickel. Signup and view all the answers

What is the inner core?

Solid metallic sphere composed of nickel and iron. Signup and view all the answers

What is the Moho?

The boundary that separates the crust from the mantle. Signup and view all the answers

What are refracted waves?

Part of a wave in shallow water slows down and bends and aligns itself with underwater contour. Signup and view all the answers

What is a shadow zone?

A belt from 105 degrees to 140 degrees distance from an earthquake epicenter in which direct P waves are absent because of refraction by Earth's core. Signup and view all the answers

Study Notes

Earthquake Concepts

Earthquake: A vibration of Earth from the rapid release of energy.
Focus: The origin point of an earthquake beneath the Earth's surface.
Faults: Fractures in Earth where movement has occurred.

Seismic Mechanics

Elastic Rebound: Rocks deform and, upon breaking, release stored energy leading to an earthquake’s vibrations.
Aftershock: A smaller earthquake that occurs following the main earthquake event.
Foreshock: A smaller earthquake that typically occurs before a more significant earthquake.

Seismology and Measurement

Seismology: The scientific study of earthquakes and seismic waves.
Seismograph: An instrument used to record the vibrations produced by seismic waves.
Seismogram: The output or the record generated by a seismograph.

Types of Seismic Waves

Surface Waves: Seismic waves that travel along Earth’s surface, often causing the most damage.
Body Waves: Seismic waves that move through the Earth's interior.
Primary (P) Waves: Compression waves that push and pull rocks in line with their direction.
Secondary (S) Waves: Waves that cause particles to shake perpendicular to their direction of travel.

Earthquake Location and Impact

Epicenter: The surface point directly above the earthquake's focus.
Circum-Pacific Belt: The major zone where most earthquakes occur globally.
Intensity: A measure of shaking at a specific location based on damage.
Magnitude: The total energy released during an earthquake.

Measurement Scales

Modified Mercalli Intensity Scale: Rates shaking and damage variances across locations.
Richter Scale: A logarithmic scale from 1 to 10 used to quantify earthquake energy release.
Moment Magnitude Scale: A more precise measure based on fault displacement and energy estimation.

Geological Effects

Liquefaction: A phenomenon where shaking causes wet soil to act like a liquid.
Seismic Sea Waves (Tsunami): Water waves generated by seismic events, volcanic activity, or landslides.

Earth Layers

Crust: The thin outer layer of Earth.
Mantle: The rocky layer beneath the crust, approximately 2900 kilometers thick.
Lithosphere: The cool and rigid layer that includes the crust and uppermost mantle.
Asthenosphere: The soft layer under the lithosphere where lithospheric plates move.

Core Structure

Lower Mantle (Mesosphere): Rigid and brittle layer constituting 80% of Earth’s material, located between 670-2900 km depth.
Core: The central part of Earth made up of iron and nickel.
Outer Core: A liquid layer within the core, characterized by mobile properties.
Inner Core: A solid metallic sphere made primarily of nickel and iron.

Geophysical Boundaries

Moho: The boundary separating the crust from the mantle.
Refracted Waves: Waves in shallow water that slow down, bend, and align with underwater contours.
Shadow Zone: An area between 105 and 140 degrees from an earthquake epicenter where direct P waves are absent due to refraction through the Earth's core.

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Test your knowledge of key Earth Science terms with this quiz covering Chapter 8 definitions. Each term is accompanied by a concise definition, helping you reinforce your understanding of earthquakes and geological processes.