Earthquake Review Flashcards

Questions and Answers

What is the difference between the focus of an earthquake and the epicenter?

The focus is the first point of movement along a fault where all earthquake waves originate, below the surface. The epicenter is the point on the surface above the focus.

How can the ground move during an earthquake?

In any direction

Small earthquakes that occur before large ones are called __________.

foreshocks

What do primary waves do?

Travel most rapidly Signup and view all the answers

What do secondary waves do?

Only travel through solids Signup and view all the answers

What type of waves are the most destructive?

Surface waves Signup and view all the answers

What do primary waves do to the rocks they travel through?

Compress and expand the rock Signup and view all the answers

Primary waves can travel through the outer core.

True Signup and view all the answers

What do secondary waves do to particles?

Shake particles at right angles to the direction the wave travels Signup and view all the answers

How many seismic stations are required to find an epicenter?

Three Signup and view all the answers

List steps to explain how the epicenter of an earthquake is determined.

Find S-P time interval, Use graph to calculate distance to epicenter, Use distance for radius of a circle around a station, Find location where 3 circles intersect Signup and view all the answers

An earthquake's magnitude is determined by the

amplitude of the largest seismic wave Signup and view all the answers

How is the distance between an epicenter and a measuring station determined?

Time interval between arrival of P waves and S waves Signup and view all the answers

What scale is most widely used by scientists for measuring earthquakes?

Moment magnitude Signup and view all the answers

What is the difference between a seismogram and a seismometer?

Seismogram is the paper record of the seismic waves. A seismometer or seismograph is the actual instrument. Signup and view all the answers

What is called the amount of shaking produced by an earthquake at a given location?

The intensity Signup and view all the answers

Each point on the Richter scale represents a wave amplitude

10 times greater than point before it Signup and view all the answers

What can affect the amount of destruction caused by earthquakes?

Intensity/duration of shaking, material on which structures are built, and design of structures Signup and view all the answers

What kind of material is safest to build structures on in an earthquake-prone area?

Solid, strong bedrock like granite Signup and view all the answers

What are generated when the ocean floor moves as the result of an earthquake?

Tsunamis Signup and view all the answers

When unconsolidated sediments become saturated with water, earthquakes can turn the soil into a fluid in a process called ____.

liquefaction Signup and view all the answers

How can earthquakes cause fires?

Can break gas lines and electrical lines Signup and view all the answers

How can scientists make short-range predictions of earthquakes?

They can measure strain in rocks near faults Signup and view all the answers

The lithosphere is made of the

crust and upper mantle Signup and view all the answers

What is Moho?

Boundary between the crust and mantle where seismic wave velocity increases Signup and view all the answers

Most of the information about Earth's interior was discovered through the study of

earthquake waves Signup and view all the answers

Secondary waves cannot travel through the outer core.

True Signup and view all the answers

Earth's inner core is solid because of

immense pressure Signup and view all the answers

Earth's inner and outer core is made of

an alloy of iron and nickel Signup and view all the answers

Study Notes

Earthquake Fundamentals

Focus: The initial point of movement along a fault beneath the Earth's surface, where all earthquake waves originate.
Epicenter: The location on the Earth's surface directly above the focus, receiving the most intense vibrations during an earthquake.

Ground Movement

During an earthquake, the ground can move in any direction.

Earthquake Types

Foreshocks: Smaller earthquakes that precede a major quake.
Aftershocks: Small earthquakes that follow a major earthquake as the materials adjust.

Seismic Waves

Primary Waves: Travel fastest, can compress and expand the rocks they move through, and can travel through both solids and liquids.
Secondary Waves: Slower, can only travel through solids, and shake particles at right angles to their direction.
Surface Waves: The most destructive type of seismic wave.

Epicenter Location

To determine the epicenter, three seismic stations are required.
Steps to locate include calculating the S-P time interval, using graphs for distance, drawing circles around each station, and finding the intersection point.

Magnitude Measurement

An earthquake's magnitude depends on the amplitude of its largest seismic wave.
The Moment Magnitude Scale is commonly used for measuring earthquakes.

Seismographs and Seismograms

Seismogram: A paper record of seismic waves.
Seismometer/Seismograph: The instrument used to detect and record seismic waves.

Intensity and Destruction Factors

Intensity: Refers to the level of shaking experienced at a specific location.
Destruction is influenced by:
- Duration and intensity of shaking.
- Quality of materials on which buildings are constructed.
- Structural design of buildings.

Foundation Safety

Solid, strong bedrock like granite is the safest material for building in earthquake-prone areas.

Tsunamis

Generated by movements of the ocean floor during an earthquake.

Liquefaction

A process where saturated unconsolidated sediments turn to fluid, causing uneven settling of buildings.

Earthquake-Induced Fires

Can break gas and electrical lines, leading to fire hazards.

Earthquake Prediction

Short-range predictions can be made by measuring strain in rocks near faults.

Earth's Structure

The Lithosphere consists of the Earth's crust and upper mantle and is divided into tectonic plates.
Moho: The boundary between the crust and mantle where seismic wave velocity increases.
Most knowledge about the Earth's interior comes from studying earthquake waves.

Inner and Outer Core

The Inner Core is solid due to immense pressure.
Both the inner and outer cores are composed of an iron-nickel alloy.

Seismic Wave Limitations

Secondary waves cannot travel through the outer core.

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Description

Test your knowledge on earthquakes with these flashcards. Learn the difference between the focus and epicenter, as well as how the ground moves during seismic events. Perfect for students and those studying geology or earth sciences.