Earthquake and Earthquake Hazard

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Questions and Answers

What is the correct relationship between amplitude and earthquake magnitude?

Larger amplitude indicates lower earthquake magnitude.

Larger amplitude corresponds to greater earthquake magnitude. (correct)

Smaller amplitude indicates higher earthquake magnitude.

Amplitude has no effect on earthquake magnitude.

Which of the following accurately describes seismic waves?

Seismic waves travel as waves at several miles per second. (correct)

Seismic waves are only generated by volcanic earthquakes.

Seismic waves only occur during shallow earthquakes.

Seismic waves do not propagate through the Earth's crust.

What is the definition of foreshocks?

Series of tremors that occur before the main earthquake. (correct)

Strong earthquakes that signify the end of seismic activity.

Weaker earthquakes that occur after the main event.

The point on the Earth's surface vertically above the focus.

Which statement is true regarding aftershocks?

They are weaker earthquakes that follow the main shocks. Signup and view all the answers

What is an active fault?

A fault that is likely to move in the future after recent activity. Signup and view all the answers

What is the significance of a seismogram?

It plots time against the intensity of motion during an earthquake. Signup and view all the answers

Which of the following best describes the role of a seismologist?

A seismologist studies earthquakes and seismic waves. Signup and view all the answers

Which type of seismic waves are characterized as primary waves?

Waves that exhibit a push-pull motion. Signup and view all the answers

What type of waves change both volume and shape of materials as they pass through?

Transverse waves Signup and view all the answers

Which of the following correctly describes secondary waves?

They cause vibrations at right angles to their direction of travel. Signup and view all the answers

What does the term 'magnitude' refer to in the context of earthquakes?

The categorization of earthquake energy released. Signup and view all the answers

Which scale is most commonly used in the United States to measure earthquake intensity?

Modified Mercalli scale Signup and view all the answers

What does the focal depth of an earthquake indicate?

The depth of the hypocenter below the Earth's surface. Signup and view all the answers

Which of the following describes the mainshock of an earthquake?

It refers to the largest earthquake in a sequence. Signup and view all the answers

What are surface waves primarily characterized by?

They move along the outer layer of the Earth. Signup and view all the answers

Plate tectonics helps to explain which of the following?

The formation of mountains and distribution of earthquakes. Signup and view all the answers

What is a common effect of quicksand?

Creation of sandboil formations Signup and view all the answers

Which safety measure should NOT be taken by individuals during an earthquake emergency?

Rushing to the nearest exit Signup and view all the answers

What type of environmental disaster is primarily caused by earthquakes under the sea?

Tsunami Signup and view all the answers

What is an important preparation step to take before an earthquake?

Strapping heavy furniture to walls Signup and view all the answers

What is a potential secondary hazard to check for before an earthquake?

Hanging light fixtures Signup and view all the answers

Which of the following is NOT recommended when evacuating a building during an earthquake?

Using the elevator Signup and view all the answers

What action should individuals take if they notice chemical spills after an earthquake?

Call the proper authorities Signup and view all the answers

Which area in a building is most likely safe during an earthquake?

In door jambs or under sturdy tables Signup and view all the answers

What is primarily measured by the Richter scale?

The magnitude of seismic energy released Signup and view all the answers

During an earthquake, what is the recommended action to protect oneself indoors?

Brace in a doorway or under sturdy furniture Signup and view all the answers

Which type of wave is primarily responsible for horizontal ground motion during an earthquake?

Love waves Signup and view all the answers

What phenomenon occurs when loose sediments behave like a liquid during an earthquake?

Liquefaction Signup and view all the answers

What should you avoid doing when in a vehicle during an earthquake?

Crossing bridges or overpasses Signup and view all the answers

What is a likely effect of ground shaking during an earthquake?

Structural damage or collapse Signup and view all the answers

What action should individuals take after experiencing an earthquake?

Stay away from damaged structures and assess for hazards Signup and view all the answers

What should individuals do to protect themselves when outside during an earthquake?

Stay away from walls and power lines Signup and view all the answers

Study Notes

Earthquake Basics

Earthquake results from sudden slippage of rock masses, creating a wave-like ground movement.
Earthquakes can be classified as tectonic or volcanic.
Deep earthquakes tend to be mild and may be felt as tremors, while shallow earthquakes can be very severe and are often preceded by foreshocks and followed by aftershocks.

Seismology and Measurements

Seismicity refers to the intensity, frequency, and distribution of earthquakes in an area.
Seismic waves carry elastic energy through the Earth at high speeds.
Seismographs detect, measure, and record ground vibrations, producing seismograms indicating time versus intensity of motion.
Seismology is the branch of geology that studies earthquakes and seismic waves.

Earthquake Components

Amplitude: Size of wiggles on a seismogram; larger amplitudes indicate greater earthquakes.
Epicenter: Point on the Earth's surface directly above the earthquake's focus.
Focus/Hypocenter: Location inside the Earth where the earthquake rupture begins.
Magnitude: Quantifies energy released during an earthquake, typically measured on the Richter scale.
Intensity: Assesses the effects of the earthquake on the Earth's surface, humans, and structures.

Types of Seismic Waves

Body Waves:
- Primary Waves (P-waves): Longitudinal waves that travel through solids, liquids, and gases; cause material to change both volume and shape.
- Secondary Waves (S-waves): Transverse waves that only travel through solids and cause sideways vibrations but are slower than P-waves.
Surface Waves: Move along the Earth’s exterior and cause the most damage due to their complex motion.
- Love Waves: Horizontal vibrations perpendicular to wave direction.
- Rayleigh Waves: Rolling/orbital ground vibrations similar to ocean waves.

Earthquake Hazards

Ground Rupture: Deformation marking the fault's intersection with the earth's surface causing fissuring and displacement.
Ground Shaking: Vibrations leading to structural damage, potentially causing secondary hazards like liquefaction or landslides.
Liquefaction: When saturated sediments behave like liquid during shaking, causing sinking or tilting of structures.
Earthquake-Induced Landslides: Movement of rocks and soil triggered by strong shaking, resulting in erosion and road blockage.
Tsunami: Waves caused by underwater earthquakes, leading to flooding and coastal erosion.

Safety Measures

During an Earthquake

Stay indoors, protect against debris by taking cover under sturdy furniture, and follow the "Duck, Cover, and Hold" method.
If outside, move to an open area, away from buildings and power lines.

After an Earthquake

Evacuate calmly from damaged buildings, using stairs instead of elevators.
Check for injuries and assist others as needed.
Call authorities to handle any hazardous materials.

Before an Earthquake

Secure heavy furniture to walls, store flammable and harmful items on lower shelves, and check for unstable objects.
Identify safe spots in the home, like doorframes and sturdy tables, where people can take refuge.

Additional Concepts

Mainshock: Largest earthquake event in a series.
Active faults are specific geologic features that have shown movement in the past and are likely to move again.
Plate tectonics explain the movement of Earth's rigid plates and relate to earthquake formation.

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Description

This quiz explores the concept of earthquakes, focusing on how the magnitude is measured through the amplitude of seismic waves. Understand the principles behind earthquake hazards and the implications of ground shaking. Test your knowledge on key terminologies and concepts related to earthquakes.