Geoscience Earthquake Flashcards

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Questions and Answers

What is an earthquake?

The vibration of Earth produced by the rapid release of energy.

What is a foreshock?

A small burst of shaking that occurs before a large earthquake.

What is the main shock?

The strongest and usually first shock.

What is an aftershock?

A smaller earthquake following the main shock of a large earthquake. Signup and view all the answers

What causes earthquakes and where do they happen?

Sudden movement of blocks and rock at plate boundaries. Signup and view all the answers

Why does the Earth shake when there is an earthquake?

The sudden release of energy causes the seismic waves that make the ground shake. Signup and view all the answers

How do scientists measure the size of earthquakes?

Using the Richter Scale and the moment magnitude scale. Signup and view all the answers

What are P waves?

A type of seismic wave that compresses and expands the ground. Signup and view all the answers

What are S waves?

A type of seismic wave that moves the ground up and down or side to side. Signup and view all the answers

Can scientists predict earthquakes?

False Signup and view all the answers

How deep was the earthquake that struck Taiwan on December 1, 2008?

Depth of 30 km. Signup and view all the answers

When was the most recent, worst earthquake to strike Taiwan?

The 921 earthquake, which struck on 21 September 1999, and claimed 2,415 lives. Signup and view all the answers

When was the most recent earthquake in the world and what was its magnitude?

The world's largest earthquake occurred on May 22, 1960, with a magnitude of 9.5. Signup and view all the answers

Where was the most recent earthquake closest to Plain, IL?

5 years ago, 2.9 magnitude, 6 km depth in Lake in the Hills, Illinois, United States. Signup and view all the answers

When and where was the strongest recent earthquake in the United States?

A magnitude 9.2 struck Prince William Sound, Alaska on March 28, 1964. Signup and view all the answers

How large was the earthquake that caused the 2004 tsunami in the Indian Ocean?

A magnitude 9.1 earthquake struck off the coast of Sumatra on December 26, 2004. Signup and view all the answers

How tall were the largest waves that struck the coastlines around the earthquake epicenter?

Some locations reported waves had reached a height of 30 feet (9 meters) or more. Signup and view all the answers

What type of plate boundary and what kind of fault caused the tsunami from the 2004 earthquake?

Subduction zone. Signup and view all the answers

What is a seismograph?

A device that records ground movements caused by seismic waves. Signup and view all the answers

What is a seismogram?

The record of an earthquake's seismic waves produced by a seismograph. Signup and view all the answers

What is the epicenter of an earthquake?

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

What is the hypocenter (focus) of an earthquake?

The zone within Earth where rock displacement produces an earthquake. Signup and view all the answers

How are earthquakes recorded?

Using seismographs. Signup and view all the answers

What is the difference between intensity and magnitude?

Magnitude measures the energy released at the source of the earthquake; intensity measures the strength of shaking produced by the earthquake at a certain location. Signup and view all the answers

List the earthquake magnitude classes and how large must an earthquake be to be considered great?

2.5 or less, 2.5 to 5.4, 5.5 to 6.0, 6.1 to 6.9; it has to be 8 or more to be considered great. Signup and view all the answers

What was the first instrument to ever record an earthquake?

Seismoscope, which recorded the times of small earthquakes. Signup and view all the answers

How much energy is released by an earthquake?

A magnitude 5.0 earthquake is about 200 tons of TNT; magnitude 6.0 is 6,270 tons; 7.0 is 199,000 tons; 8.0 is 6,270,000 tons. Signup and view all the answers

Study Notes

Earthquake Basics

An earthquake is the vibration of Earth resulting from a rapid release of energy.
Foreshocks are smaller tremors that occur prior to a larger earthquake, while aftershocks follow the main event.

Earthquake Mechanics

The strongest shock in an earthquake is known as the main shock.
Earthquakes occur due to the sudden movement of blocks and rocks along plate boundaries.

Seismic Wave Types

P waves compress and expand the ground, while S waves move the ground up and down or side to side.
Seismographs are devices that record ground movements caused by seismic waves.

Measuring Earthquakes

The Richter Scale has been largely replaced by the Moment Magnitude Scale for measuring earthquake size, offering a more accurate assessment.
Magnitude is different from intensity; magnitude assesses energy released, while intensity measures the shaking effects at specific locations.

Notable Earthquake Events

The 2004 Indian Ocean earthquake had a magnitude of 9.1 and triggered a devastating tsunami.
The world's largest earthquake, a magnitude 9.5 event, occurred near Valdivia, Chile, on May 22, 1960.
The strongest earthquake in the United States, with a magnitude of 9.2, struck Prince William Sound, Alaska, on March 28, 1964.

Earthquake Characteristics and Effects

Tsunami waves from the 2004 event reached heights of 30 feet in some locations.
Different earthquake magnitude classes range from minor (2.5 or less) to great (8 or more).

Earthquake Depth and Focus

The hypocenter (or focus) is where rock displacement happens, while the epicenter is the point on the surface directly above it.
An earthquake that struck Taiwan on December 1, 2008, had a depth of 30 km.

Earthquake Prediction Challenges

Currently, scientists have no reliable method to predict earthquakes and do not expect breakthroughs in the near future.

Historical Instruments

The seismoscope was the first instrument to record earthquakes, functioning similarly to modern seismographs.

Energy Release

Energy release from earthquakes scales significantly; a magnitude 5.0 quake releases energy equivalent to 200 tons of TNT, with increases for larger magnitudes.

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Description

Test your knowledge of earthquakes with these flashcards designed for Geoscience. Learn key terms such as foreshock, main shock, and aftershock, along with their definitions. Perfect for students looking to reinforce their understanding of seismic activity.