Earth Science Chapter on Lithosphere and Asthenosphere

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does the term lithosphere refer to?

The inner core of the Earth

A rigid layer formed by the crust and upper mantle (correct)

A soft, weak zone within the Earth

A layer of liquid rock beneath the crust

How thick is the asthenosphere, approximately?

5 to 10 km

20 to 50 km

80 to 150 km (correct)

200 to 300 km

Where are most earthquakes concentrated?

In areas with wide continental shelves

In the midst of ocean abyssal plains

Uniformly across all continents

In discrete belts and along volcanic islands (correct)

Which geographical feature is most likely to experience numerous earthquakes?

Ocean trenches and associated island arcs Signup and view all the answers

What term describes the processes that deform the crust and mantle?

Tectonics Signup and view all the answers

Which of the following regions has a high frequency of earthquakes?

The Middle East and Tibet Signup and view all the answers

Which event was a result of large earthquakes near ocean trenches?

Creation of large tsunamis Signup and view all the answers

What characterizes the asthenosphere?

A soft and weak zone allowing movement of the lithosphere Signup and view all the answers

What forms at the site of an ocean-ocean convergent boundary?

An ocean trench Signup and view all the answers

What is the process called when one plate slides beneath another?

Subduction Signup and view all the answers

What geological feature is created by the convergence of an oceanic plate and a continental plate?

A volcanic arc Signup and view all the answers

How does the crust respond when two continental plates converge?

It deforms and thickens Signup and view all the answers

Where are the volcanoes of the Pacific Ring of Fire located?

Surrounding the Pacific Ocean Signup and view all the answers

What type of motion occurs at transform boundaries?

Plates slide horizontally past each other Signup and view all the answers

What is a characteristic of transform faults associated with mid-ocean ridges?

They are generally perpendicular to the ridge axis Signup and view all the answers

Which of the following correctly describes a fracture zone?

A former transform fault without relative motion Signup and view all the answers

What effect can the upward movement of magma beneath a volcano have on surrounding rocks?

It can fracture and uplift adjacent rocks. Signup and view all the answers

What is a volcanic tremor?

A series of small earthquakes resulting from magma movement. Signup and view all the answers

What happens to rocks before faulting occurs?

They undergo elastic behavior while being strained. Signup and view all the answers

Which phenomenon can cause ground shaking due to volcanic activity?

Small earthquakes as rocks break before a landslide. Signup and view all the answers

How do mine blasts and nuclear explosions generate seismic waves?

They compress the Earth's surface abruptly. Signup and view all the answers

What initiates the slippage along a fault?

Accumulated stress reaching a critical level. Signup and view all the answers

What can be a signal of an impending volcanic eruption?

Volcanic tremors and small earthquakes. Signup and view all the answers

What occurs to the strained rocks after faulting?

They can return to their original shape. Signup and view all the answers

What occurred at 4:19 AM on August 02, 1968, in Casiguran, Aurora?

A severe earthquake struck Signup and view all the answers

Which oceanic plate is subducting beneath the Eurasian plate?

Indian-Australian Plate Signup and view all the answers

What happens when a seismic wave passes from a slower material to a faster one?

It is refracted to a shallower angle Signup and view all the answers

What is indicated by the yellow dots near the fault line?

Locations of smaller, related earthquakes Signup and view all the answers

What was one consequence of the 1968 Casiguran earthquake?

Collapse of Ruby Tower Signup and view all the answers

What action did the Philippine government take in response to geologic hazards?

Issued a long-term policy for hazard assessment Signup and view all the answers

What type of rays are affected when seismic waves change from fast to slow materials?

Rising seismic rays Signup and view all the answers

What is the intensity level of the earthquake that struck Casiguran according to the Rossi-Forel Intensity Scale?

VIII Signup and view all the answers

What is indicated by the yellow dots on the map described?

Aftershocks Signup and view all the answers

Which earthquake caused moderate damage but only injured two people?

2010 Canterbury quake Signup and view all the answers

What was a significant factor contributing to the destruction during the 2011 Christchurch quake?

Location of the epicenter Signup and view all the answers

What type of fault is shown by the red lines on the map?

Thrust movement Signup and view all the answers

How high can tsunami waves reach as described from the 2004 earthquake?

20 to 30 m Signup and view all the answers

What resulted from the liquefaction of soil during the 2011 Christchurch earthquake?

Expulsion of water from the ground Signup and view all the answers

What was the magnitude of the undersea earthquake off the coast of Sumatra on December 26, 2004?

9.1 Signup and view all the answers

Which characteristic of the 2010 Canterbury earthquake is mentioned?

Not on the plate boundary Signup and view all the answers

Study Notes

Earth's Lithosphere and Asthenosphere

The lithosphere is a rigid layer formed from the crust and upper mantle, derived from the Greek word "lithos" meaning "stone."
The asthenosphere is a soft, weak layer beneath the lithosphere, approximately 80 to 150 km thick. Its base can be found up to 250 km deep.

Earthquake Distribution

Earthquakes are not uniformly distributed; they mainly occur in discrete belts.
Notable earthquake zones include the western coasts of North and South America and mid-ocean ridges.
Regions of high seismic activity include the Middle East, China, and Tibet, while abyssal plains often have few earthquakes.
Large earthquakes can create tsunamis, as evidenced by disasters in the Indian Ocean (2004) and Japan (2011).

Tectonic Activity and Plate Convergence

Tectonic activity, which includes earthquakes and volcanic eruptions, occurs primarily along plate boundaries with active deformation.
Oceanic-oceanic convergence forms ocean trenches and subduction zones known for large earthquakes.
When an oceanic plate converges with a continental plate, it results in crust compression and uplift.

Pacific Ring of Fire

The Pacific Ring of Fire comprises volcanoes surrounding the Pacific Ocean, linked to subduction activities on both sides.
It extends from the southwestern Pacific, through the Philippines, Japan, Alaska, and down western coasts of the Americas.

Continental Collisions and Transform Boundaries

Continental collision occurs at continent-continent convergent boundaries, generating major mountain ranges.
Transform boundaries allow plates to slip horizontally past each other, creating transform faults typically associated with mid-ocean ridges.

Earthquake Mechanisms and Volcanic Activity

Steep volcanic slopes can lead to catastrophic landslides, causing ground shaking and smaller precursor earthquakes.
Magma movement beneath a volcano can fracture rocks, leading to volcanic tremors and minor earthquakes, alerting geologists to potential eruptions.

Other Sources of Seismic Waves

Landslides, both terrestrial and underwater, can cause seismic waves, often detected by seismometers.
Human activities such as mine blasts and nuclear detonations also generate detectable seismic waves, important for monitoring compliance with test-ban treaties.

Earthquake Processes and Aftershocks

Prior to faulting, rocks undergo minor deformation until sudden slippage occurs.
Aftershocks, smaller earthquakes following a major event, help reduce stress and allow rocks to return to their elastic behavior.

Notable Earthquakes

The 2010 New Zealand earthquake (magnitude 7.1) was shallow and caused moderate damage, while the 2011 Christchurch quake, though smaller, led to significant destruction due to its proximity to the city.
The 2004 Indian Ocean earthquake (magnitude 9.1) triggered a massive tsunami, affecting multiple countries with waves reaching heights of 20-30 meters off the coasts.

Seismic Wave Behavior

Seismic waves refract when transitioning between materials of different densities, with the direction of refraction depending on whether they slow down or speed up.
Seismic waves effectively travel through diverse geological materials in Earth's crust and mantle.

GeoHazard Assessments in the Philippines

The Philippine government established a long-term strategy for geological hazard protection, mandating preliminary geo-hazard assessments for land development projects.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Explore the concepts of the lithosphere and asthenosphere in this quiz. Learn how these layers of the Earth interact and their significance in geology. Test your knowledge on the characteristics and functions of these crucial geological formations.