Concept #1 Quiz

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Choose the best possible answer to the following questions about Key Concept 1 "Earthquake basics."

This activity contains 8 questions.

An earthquake’s source of energy is located at the _, but the location at the land surface above that point is called the __.

epicenter, focusfault, hypocenterhypocenter, faultfocus, epicenter

Identify the indicated earthquake components by selecting the correct response.

The letters A through D appear on an image associated with this question.

This question presents 4 items numbered 2.1 through 2.4. Each item is presented with a pulldown menu containing the letters A through D. For each item below, use the pull-down menu to select the letter that labels the correct part of the image.

2.1 epicenter	[hint]
2.2 focus	[hint]
2.3 fault scarp	[hint]
2.4 fault	[hint]

The “focus” and “epicenter” associated with earthquakes are _ and _, respectively.

the point on the surface directly above the epicenter / the point where fault “slip” is initiatedthe point where fault “slip” is initiated / the point on the surface directly above the focusthe point on the surface directly below the epicenter / the point where fault “slip” is initiated the point where fault “slip” is initiated / the point on the fault directly beneath the focus

Match the following basic earthquake terms with the appropriate description:

A matching question presents 7 answer choices and 7 items. The answer choices are lettered A through G. The items are numbered 4.1 through 4.7. Screen readers will read the answer choices first. Then each item will be presented along with a select menu for choosing an answer choice. Using the pull-down menus, match each item in the left column to the corresponding item in the right column.

	slow and gradual displacement along a fault, usually resulting in little earthquake activity
	the location on the surface of the earth, below which the point of rupture occurred
	a tremor or smaller earthquake that precedes a main larger earthquake
	a tremor or smaller earthquake that precedes a main larger earthquake
	a “snap back” action – the cause of earthquakes
	large fractures in the Earth along which rocks are moved and/or displaced, causing earthquakes
	the source point from which all earthquake energy radiates

4.1 fault creep
4.2 elastic rebound
4.3 aftershock
4.4 foreshock
4.5 fault
4.6 epicenter
4.7 focus

How is a “fault,” a “focus,” and an “epicenter” related to an earthquake?

When faults “slip,” the point of slippage is the focus where all energy is released. The epicenter is the point on the surface directly above the focus, used for location purposes.When an epicenter “slips,” the fault is the point of slippage where all energy is released to form the earthquake. The focus is the point on the surface used for location purposes.When a focus “slips,” the point of slippage is the fault, directly below the epicenter on the surface. The epicenter is simply used for location purposes.When faults “slip,” the point of slippage is the epicenter, directly below the focus on the surface. The focus is the source point for all the energy released (the earthquake) resulting from the slippage.

Which of the following best describes “elastic rebound” theory of earthquakes?

As an earthquake occurs, the plastically deformed rocks along the fault gently glide back to their original shape as much as possible.Just before an earthquake occurs, the elastic rocks along the fault spring forward, then backward.As an earthquake occurs, the elastically deformed rocks along the fault spring back to their original shape as much as possible.Just after the earthquake occurs, the elastic rocks along the fault spring forward, then backward.

Why do “main” earthquakes have “foreshocks” and “aftershocks”?

Foreshocks occur due to small adjustments after the main earthquake, and aftershocks occur due to the buildup of strain prior to the main earthquake.Foreshocks are required in order for an earthquake to occur, whereas aftershocks occur only if foreshocks do not occur.Foreshocks result if the fault makes enough adjustments to prevent a main earthquake. Aftershocks result if the foreshocks do not do their job. Foreshocks occur due to small slippages on minor parts of faults, and aftershocks occur due to similar small adjustments after the main earthquake.

Which of the following would NOT be a situation that would produce an earthquake?

fluctuations of Earth’s magnetic fieldthe collapse of a buildinga nuclear blastcracking of a large mass of rock to release strain energy

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