Geology: Earthquakes and Plate Tectonics

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Questions and Answers

What is the primary function of seismograph stations?

Find the epicenter of an earthquake (correct)

Report on the structural damage from earthquakes

Report the weather

Connect with satellite images of earthquakes

What structural feature is formed when magma pushes its way through rock layers?

Hotspot

Volcano

Rift

Dike (correct)

How many seismic measurements are needed to accurately determine the epicenter of an earthquake?

Four

Three (correct)

Two

One

What geological feature typically occurs at the convergence of oceanic and continental crusts?

Continental arc (C) Signup and view all the answers

What is the term for the boundary between oceanic and continental plates?

Continental margin (B) Signup and view all the answers

What is the Moho?

Region where seismic waves change speed (A), Boundary between the crust and mantle (D) Signup and view all the answers

Which of the following statements is true regarding the Earth's magnetic field and rocks?

Iron-rich minerals in molten rocks align with the Earth's magnetic field (A) Signup and view all the answers

What defines the Moho's significance in geology?

It marks the transition layer between crust and mantle (B) Signup and view all the answers

What is a syncline characterized by?

When rock layers are folded downward in a 'U' shape (D) Signup and view all the answers

At what boundary do mountains typically form?

Convergent boundary (C) Signup and view all the answers

What does the depth of focus of an earthquake refer to?

Where rocks begin to break (D) Signup and view all the answers

What characteristic defines the lithosphere?

The rigid outer layer that floats on the asthenosphere (A) Signup and view all the answers

What process occurs during liquefaction?

The soil behaves like quicksand and releases water (A) Signup and view all the answers

Which of the following correctly describes the Andes Mountains' formation?

From the collision of the Nazca Plate and South American Plate (C) Signup and view all the answers

What type of fault is primarily involved in mountain building?

Reverse or thrust fault (B) Signup and view all the answers

What distinguishes a sill in geological terms?

It has contact metamorphism on both the top and bottom (B) Signup and view all the answers

What is the typical thickness range of the Earth's crust?

5–70 km (A) Signup and view all the answers

What is a triple junction in geology?

A region where three tectonic plates meet (B) Signup and view all the answers

What is the correct definition of declination?

The difference between the magnetic North Pole and the geographic North Pole (B) Signup and view all the answers

Where in the United States is the highest risk of earthquakes?

Western coast of California (B) Signup and view all the answers

What type of volcanic formation is primarily associated with island arc complexes?

Andesitic stratovolcanoes (D) Signup and view all the answers

Study Notes

Seismograph Stations

Seismograph stations are used to locate the epicenter of an earthquake.

Magma Intrusions

A dike is formed when magma pushes through rock layers vertically or diagonally.

Earthquake Epicenter Location

Three seismic measurements are needed to pinpoint an earthquake's epicenter.

Oceanic-Continental Plate Convergence

A continental arc typically forms where oceanic and continental plates converge.

Plate Boundaries

The continental margin is the divider between oceanic and continental plates.

Earth's Magnetic Field Recording

Igneous rocks, like basalt, record changes in the Earth's magnetic field.
Iron-rich minerals in molten rocks align with the magnetic field during cooling and solidification.

Moho Definition

The Moho is the boundary between the Earth's crust and mantle.
The Moho is also known as the Mohorovičić discontinuity.
Seismic waves change speed at the Moho.

Folding of Rock Layers

A syncline is a downward fold in rock layers, appearing as a "U" shape.

Earth's Interior

The image displayed shows the Earth's mantle.

Earthquake Depth

Earthquakes originate approximately 0–700 km below the Earth's surface where rocks begin to break.

Mountain Formation

Mountains usually form at convergent boundaries.

Earth's Layers

The lithosphere is the hard, rigid outer layer of the Earth above the asthenosphere.

Liquefaction

During liquefaction, soil behaves like quicksand, releasing water to the surface.

Dike Composition

Igneous rocks in dikes are typically coarse-grained due to slow cooling beneath the Earth's surface.

Mountain Formation (Andes)

The Andes Mountains formed from the collision of the Nazca Plate and the South American Plate.

Volcanic Landforms

Island arc complexes are mostly composed of andesitic stratovolcanoes at oceanic margins.

Earthquake Risk in the US

The western coast of California has the highest earthquake risk in the US.

Fault Types and Mountain Building

Reverse or thrust faults are commonly involved in mountain building.

Sill Differentiation

Sills are differentiated from other rock layers due to the presence of contact metamorphism around both the top and bottom of the sill.

Earth's Crust Thickness

The Earth's crust is typically 5–70 km thick.

Crust and Asthenosphere

The Earth's crust sits atop the asthenosphere.

Triple Junctions

A triple junction is an area where three tectonic plates meet.

Magnetic Declination

Declination is the difference between the magnetic North Pole and the geographic North Pole.

Aftershocks

Aftershocks are additional shaking that follows an initial earthquake; they can be numerous and severe.

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Description

This quiz covers essential concepts related to seismic activity, the formation of magma intrusions, and the dynamics of plate boundaries. You'll explore topics like earthquake epicenter location, the Moho, and the significance of the Earth's magnetic field in geology. Test your understanding of these fundamental geological principles!