## Breadcrumb

-  Science 
-  Science Explorer 
-  Natural Hazards 

# How the Earth Moves

## Unstable Ground Beneath Our Feet

### Even shallow sloped surfaces can move and fail as landslides.

Learn about Landslides

## The Story of Plate Tectonics

### Earth’s surface moves at many depths, including at plate boundaries.

Read about Our Dynamic Earth

## The Science of Earthquakes

### Typically, earthquakes are felt out West. But, in reality, tremors can shake most parts of the United States.

Learn about Earthquake Hazards

## Understanding Coastal Erosion

### Wind, rain, and water cut into land surfaces, eroding away dirt and rocks.

Watch Video about Coastal Hazards

## Living with a Volcano in Your Backyard

### And sometimes the Earth itself will bubble up and erupt.

Learn How to Live Around a Volcano

            -              Overview           
            -              Publications           
            -              Science           
            -              Maps           
            -              Multimedia           
            -              News           
            -              FAQ           

### **The Ground Beneath Our Feet**

From plate tectonics to ocean tides, energy is constantly being transferred throughout the planet. As Earth’s plates slowly move and grind against each other, they build the mountains that tower above us. If the plates stick, then slip, they release their energy through the earthquakes that shake us. The USGS is dedicated to better understanding our planet and the processes that shape our planet.

View Media Details

### **Let’s Hear from the Experts**

USGS has some of the premiere Earth scientists in the world. Although our researchers study everything from bees to trees to tides and slides, we wanted to specifically showcase our hazards researchers. Here are a few presentations from our volcano, earthquake, and landslide specialists.

                                          - Download Video

View Media Details

                                          - Download Video

View Media Details

                                          - Download Video

View Media Details

### Dive Deeper into Understanding How the Earth Moves

There is so much to learn about the different ways Earth moves beneath our feet. Take a deeper dive into our different programs that look at why things move and how we study them.

Earthquakes

## Earthquakes

Volcanic Eruptions

## Volcanic Eruptions

Landslides

## Landslides

Coastal Change

## Coastal Change

## Publications

September 17, 2018

####                 Science for a risky world—A U.S. Geological Survey plan for risk research and applications              

Natural Hazards Mission Area, Reducing Risk

August 1, 2004

####                 Landslide types and processes              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

January 1, 1996

####                 This dynamic earth: the story of plate tectonics              

Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center

View All

## Science

link

July 25, 2022

####                 Active Volcanoes of Hawaii              

Hawaiian Volcano Observatory

link

July 25, 2022

####   Active Volcanoes of Hawaii

Learn More

link

February 22, 2021

####                 Barry Arm, Alaska Landslide and Tsunami Monitoring              

Natural Hazards Mission Area, Landslide Hazards Program

link

February 22, 2021

####   Barry Arm, Alaska Landslide and Tsunami Monitoring

Learn More

link

June 16, 2020

####                 Coastal Change Hazards - Technical Capabilities and Applications              

Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, St. Petersburg Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center

link

June 16, 2020

####   Coastal Change Hazards - Technical Capabilities and Applications

Learn More

link

October 11, 2019

####                 Liquefaction Hazard Maps              

Natural Hazards Mission Area, Earthquake Hazards Program

link

October 11, 2019

####   Liquefaction Hazard Maps

Learn More

link

March 17, 2016

####                 Volcano Hazards Assessments Help Mitigate Disasters              

Natural Hazards Mission Area, Volcano Hazards Program

link

March 17, 2016

####   Volcano Hazards Assessments Help Mitigate Disasters

Learn More

View All

## Multimedia

A USGS geologist stands in a crack in tide flat sediment, Alaska

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

Debris flow monitoring at Chalk Cliffs, CO (2017)

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

Big Sur landslide on May 20, 2017

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

Shaking in the Atwood Building in Anchorage, Alaska

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

Oso Landslide Computer Simulations

January 7, 2015

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

January 7, 2015

#### Oso Landslide Computer Simulations

link

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

Magnitude 9.2: The 1964 Great Alaska Earthquake

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

USGS Damage from the magnitude 9.2 earthquake in Alaska 

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

View All

## News

Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

August 12, 2022

####   Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

The temblor that changed earthquake science turns 30

June 22, 2022

####   The temblor that changed earthquake science turns 30

Volcanoes and USGS Volcano Science: Just the Facts

April 12, 2022

####   Volcanoes and USGS Volcano Science: Just the Facts

View All

September 17, 2018

####                 Science for a risky world—A U.S. Geological Survey plan for risk research and applications              

Natural Hazards Mission Area, Reducing Risk

August 1, 2004

####                 Landslide types and processes              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

January 1, 1996

####                 This dynamic earth: the story of plate tectonics              

Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center

link

July 25, 2022

####                 Active Volcanoes of Hawaii              

Hawaiian Volcano Observatory

link

July 25, 2022

####   Active Volcanoes of Hawaii

Learn More

link

February 22, 2021

####                 Barry Arm, Alaska Landslide and Tsunami Monitoring              

Natural Hazards Mission Area, Landslide Hazards Program

link

February 22, 2021

####   Barry Arm, Alaska Landslide and Tsunami Monitoring

Learn More

link

June 16, 2020

####                 Coastal Change Hazards - Technical Capabilities and Applications              

Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, St. Petersburg Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center

link

June 16, 2020

####   Coastal Change Hazards - Technical Capabilities and Applications

Learn More

link

October 11, 2019

####                 Liquefaction Hazard Maps              

Natural Hazards Mission Area, Earthquake Hazards Program

link

October 11, 2019

####   Liquefaction Hazard Maps

Learn More

link

March 17, 2016

####                 Volcano Hazards Assessments Help Mitigate Disasters              

Natural Hazards Mission Area, Volcano Hazards Program

link

March 17, 2016

####   Volcano Hazards Assessments Help Mitigate Disasters

Learn More

link

September 15, 2014

####                 Understanding plate motions              

link

September 15, 2014

####   Understanding plate motions

Learn More

February 7, 2020

####                 Seismicity of the Earth 1900–2018              

Natural Hazards Mission Area, Geologic Hazards Science Center

December 1, 2003

####                 Hawaii's volcanoes revealed              

January 1, 1979

####                 Map showing landslides and areas of susceptibility to landsliding in Puerto Rico              

January 1, 1972

####                 Generalized tectonic map of North America              

November 18, 2021

####   PubTalk-11/2021: Busting Myths About One of the Largest Volcanic Systems in the World - The Top 10 Misconceptions about Yellowstone Volcanism

Busting Myths About One of the Largest Volcanic Systems in the World - The Top 10 Misconceptions about Yellowstone Volcanism

By Michael Poland, USGS Scientist-in-charge, Yellowstone Volcano Observatory

Yellowstone Volcano Observatory, Yellowstone, Communications and Publishing, Public Lecture Series

A USGS geologist stands in a crack in tide flat sediment, Alaska

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

Debris flow monitoring at Chalk Cliffs, CO (2017)

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

Big Sur landslide on May 20, 2017

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

Shaking in the Atwood Building in Anchorage, Alaska

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

Oso Landslide Computer Simulations

January 7, 2015

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

January 7, 2015

#### Oso Landslide Computer Simulations

link

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

Magnitude 9.2: The 1964 Great Alaska Earthquake

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

USGS Damage from the magnitude 9.2 earthquake in Alaska 

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

August 12, 2022

####   Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

Between January 14-15, 2022, volcanic explosions destroyed much of Hunga Tonga-Hunga Ha'apai, an uninhabited island in the Tonga archipelago in the...

Read Article

The temblor that changed earthquake science turns 30

June 22, 2022

####   The temblor that changed earthquake science turns 30

To mark the 30th anniversary of a Southern California earthquake, we’ll note why it was significant and listen to USGS employees share their own quake...

Read Article

Volcanoes and USGS Volcano Science: Just the Facts

April 12, 2022

####   Volcanoes and USGS Volcano Science: Just the Facts

Volcanoes are an incredible feature of Earth’s geologic environment – at once awe-inspiring and terrifying. They remind us that the planet we call...

Read Article

Take a Tour of the Earthquake Hazards Program Site

March 18, 2022

####   Take a Tour of the Earthquake Hazards Program Site

Or...How to Find USGS Earthquake Information Quickly!

Read Article

The largest landslide in the world

November 22, 2021

####   The largest landslide in the world

Yellowstone is well-known as one of the largest volcanic systems in the world. Few people know, however, that the largest-known subaerial landslide on...

Read Article

10-Year Anniversary of US’s Most Widely Felt Earthquake

August 4, 2021

####   10-Year Anniversary of US’s Most Widely Felt Earthquake

Ten years ago, in the early afternoon of August 23, 2011, millions of people throughout the eastern U.S. felt shaking from a magnitude 5.8 earthquake...

Read Article

Post-wildfire Landslides Becoming More Frequent in Southern California

February 25, 2021

####   Post-wildfire Landslides Becoming More Frequent in Southern California

Southern California can now expect to see post-wildfire landslides occurring almost every year, with major events expected roughly every ten years, a...

Read Article

Mount St. Helens’ 1980 Eruption Changed the Future of Volcanology

May 14, 2020

####   Mount St. Helens’ 1980 Eruption Changed the Future of Volcanology

If scientists armed with today's monitoring tools and knowledge could step back in time to the two months before May 18, 1980, they would have been...

Read Article

The Complex Dynamics of Geyser Eruptions

May 10, 2017

####   The Complex Dynamics of Geyser Eruptions

Despite two centuries of scientific study, basic questions persist about geysers—why do they exist? What determines their behavior?

Read Article

Northern Alaska Coastal Erosion Threatens Habitat and Infrastructure

July 1, 2015

####   Northern Alaska Coastal Erosion Threatens Habitat and Infrastructure

Read Article

link

####                 What is an earthquake and what causes them to happen?              

An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel. In California there are two plates - the Pacific Plate and the North...

link

####   What is an earthquake and what causes them to happen?

An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel. In California there are two plates - the Pacific Plate and the North...

Learn More

link

####                 What is liquefaction?              

Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the...

link

####   What is liquefaction?

Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the...

Learn More

link

####                 What is a landslide and what causes one?              

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material...

link

####   What is a landslide and what causes one?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material...

Learn More

link

####                 How Do Volcanoes Erupt?              

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. The...

link

####   How Do Volcanoes Erupt?

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. The...

Learn More

### **The Ground Beneath Our Feet**

From plate tectonics to ocean tides, energy is constantly being transferred throughout the planet. As Earth’s plates slowly move and grind against each other, they build the mountains that tower above us. If the plates stick, then slip, they release their energy through the earthquakes that shake us. The USGS is dedicated to better understanding our planet and the processes that shape our planet.

View Media Details

### **Let’s Hear from the Experts**

USGS has some of the premiere Earth scientists in the world. Although our researchers study everything from bees to trees to tides and slides, we wanted to specifically showcase our hazards researchers. Here are a few presentations from our volcano, earthquake, and landslide specialists.

                                          - Download Video

View Media Details

                                          - Download Video

View Media Details

                                          - Download Video

View Media Details

### Dive Deeper into Understanding How the Earth Moves

There is so much to learn about the different ways Earth moves beneath our feet. Take a deeper dive into our different programs that look at why things move and how we study them.

Earthquakes

## Earthquakes

Volcanic Eruptions

## Volcanic Eruptions

Landslides

## Landslides

Coastal Change

## Coastal Change

## Publications

September 17, 2018

####                 Science for a risky world—A U.S. Geological Survey plan for risk research and applications              

Natural Hazards Mission Area, Reducing Risk

August 1, 2004

####                 Landslide types and processes              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

January 1, 1996

####                 This dynamic earth: the story of plate tectonics              

Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center

View All

## Science

link

July 25, 2022

####                 Active Volcanoes of Hawaii              

Hawaiian Volcano Observatory

link

July 25, 2022

####   Active Volcanoes of Hawaii

Learn More

link

February 22, 2021

####                 Barry Arm, Alaska Landslide and Tsunami Monitoring              

Natural Hazards Mission Area, Landslide Hazards Program

link

February 22, 2021

####   Barry Arm, Alaska Landslide and Tsunami Monitoring

Learn More

link

June 16, 2020

####                 Coastal Change Hazards - Technical Capabilities and Applications              

Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, St. Petersburg Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center

link

June 16, 2020

####   Coastal Change Hazards - Technical Capabilities and Applications

Learn More

link

October 11, 2019

####                 Liquefaction Hazard Maps              

Natural Hazards Mission Area, Earthquake Hazards Program

link

October 11, 2019

####   Liquefaction Hazard Maps

Learn More

link

March 17, 2016

####                 Volcano Hazards Assessments Help Mitigate Disasters              

Natural Hazards Mission Area, Volcano Hazards Program

link

March 17, 2016

####   Volcano Hazards Assessments Help Mitigate Disasters

Learn More

View All

## Multimedia

A USGS geologist stands in a crack in tide flat sediment, Alaska

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

Debris flow monitoring at Chalk Cliffs, CO (2017)

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

Big Sur landslide on May 20, 2017

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

Shaking in the Atwood Building in Anchorage, Alaska

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

Oso Landslide Computer Simulations

January 7, 2015

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

January 7, 2015

#### Oso Landslide Computer Simulations

link

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

Magnitude 9.2: The 1964 Great Alaska Earthquake

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

USGS Damage from the magnitude 9.2 earthquake in Alaska 

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

View All

## News

Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

August 12, 2022

####   Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

The temblor that changed earthquake science turns 30

June 22, 2022

####   The temblor that changed earthquake science turns 30

Volcanoes and USGS Volcano Science: Just the Facts

April 12, 2022

####   Volcanoes and USGS Volcano Science: Just the Facts

View All

September 17, 2018

####                 Science for a risky world—A U.S. Geological Survey plan for risk research and applications              

Natural Hazards Mission Area, Reducing Risk

August 1, 2004

####                 Landslide types and processes              

Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

January 1, 1996

####                 This dynamic earth: the story of plate tectonics              

Natural Hazards Mission Area, Volcano Hazards Program, Volcano Science Center

link

July 25, 2022

####                 Active Volcanoes of Hawaii              

Hawaiian Volcano Observatory

link

July 25, 2022

####   Active Volcanoes of Hawaii

Learn More

link

February 22, 2021

####                 Barry Arm, Alaska Landslide and Tsunami Monitoring              

Natural Hazards Mission Area, Landslide Hazards Program

link

February 22, 2021

####   Barry Arm, Alaska Landslide and Tsunami Monitoring

Learn More

link

June 16, 2020

####                 Coastal Change Hazards - Technical Capabilities and Applications              

Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, St. Petersburg Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center

link

June 16, 2020

####   Coastal Change Hazards - Technical Capabilities and Applications

Learn More

link

October 11, 2019

####                 Liquefaction Hazard Maps              

Natural Hazards Mission Area, Earthquake Hazards Program

link

October 11, 2019

####   Liquefaction Hazard Maps

Learn More

link

March 17, 2016

####                 Volcano Hazards Assessments Help Mitigate Disasters              

Natural Hazards Mission Area, Volcano Hazards Program

link

March 17, 2016

####   Volcano Hazards Assessments Help Mitigate Disasters

Learn More

link

September 15, 2014

####                 Understanding plate motions              

link

September 15, 2014

####   Understanding plate motions

Learn More

February 7, 2020

####                 Seismicity of the Earth 1900–2018              

Natural Hazards Mission Area, Geologic Hazards Science Center

December 1, 2003

####                 Hawaii's volcanoes revealed              

January 1, 1979

####                 Map showing landslides and areas of susceptibility to landsliding in Puerto Rico              

January 1, 1972

####                 Generalized tectonic map of North America              

November 18, 2021

####   PubTalk-11/2021: Busting Myths About One of the Largest Volcanic Systems in the World - The Top 10 Misconceptions about Yellowstone Volcanism

Busting Myths About One of the Largest Volcanic Systems in the World - The Top 10 Misconceptions about Yellowstone Volcanism

By Michael Poland, USGS Scientist-in-charge, Yellowstone Volcano Observatory

Yellowstone Volcano Observatory, Yellowstone, Communications and Publishing, Public Lecture Series

A USGS geologist stands in a crack in tide flat sediment, Alaska

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

December 17, 2018

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

#### A USGS geologist stands in a crack in tide flat sediment, Alaska

link

A USGS scientist stands in a crack in tide flat sediment that opened during strong shaking in the November 30, 2018 Anchorage earthquake. This upland ground crack near Cottonwood Creek, Palmer Slough had horizontal displacements of ~2.5ft locally and observed maximum depth of ~3ft. The crack was observed ~150ft from the active river channel.

Alaska Science Center

Debris flow monitoring at Chalk Cliffs, CO (2017)

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

July 14, 2017

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

#### Debris flow monitoring at Chalk Cliffs, CO (2017)

link

The USGS and its cooperators have installed debris-flow monitoring equipment in the largest drainage basin at Chalk Cliffs, CO. Data collection at this site supports research on the hydrologic factors that control debris-flow initiation, entrainment, and flow dynamics.

Natural Hazards, Landslide Hazards, Geologic Hazards Science Center, Communications and Publishing

Big Sur landslide on May 20, 2017

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

May 27, 2017

#### Big Sur landslide on May 20, 2017

link

#### Big Sur landslide on May 20, 2017

link

USGS air photo of the Mud Creek landslide, taken on May 27, 2017.

Natural Hazards, Coastal and Marine Hazards and Resources Program, Landslide Hazards, California, Big Sur Landslides

Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

May 20, 2016

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

#### Shaking of Frontier Building — Anchorage, Alaska, During Mw7.1 Earthquake, January 24, 2016

link

This video presents a visualization of shaking that was recorded in the Frontier Building in Anchorage, Alaska, during the Mw7.1 earthquake, January 24, 2016, Iniskin, Alaska. It exhibits how a tall building behaves and performs during strong earthquake shaking.

Natural Hazards, Earthquake Hazards, Communications and Publishing

Shaking in the Atwood Building in Anchorage, Alaska

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

March 30, 2016

#### Shaking in the Atwood Building in Anchorage, Alaska

link

#### Shaking in the Atwood Building in Anchorage, Alaska

link

This video presents a visualization of how the Atwood Building in Anchorage, Alaska, shook during the M7.1 January 24, 2016, Iniskin, Alaska, earthquake. The building was instrumented by U.S. Geological Survey to obtain data to study its behavior and performance during strong shaking.

Communications and Publishing

Oso Landslide Computer Simulations

January 7, 2015

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

January 7, 2015

#### Oso Landslide Computer Simulations

link

#### Oso Landslide Computer Simulations

link

A large destructive landslide occurred near Oso, Washington on March 22, 2014. Computer simulations indicate that it could have behaved very differently (with much less mobility and consequent destructiveness) if the ground had been less porous and water-saturated. This video shows the results of two computer simulations.

Communications and Publishing

Magnitude 9.2: The 1964 Great Alaska Earthquake

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

January 1, 2014

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

#### Magnitude 9.2: The 1964 Great Alaska Earthquake

link

Magnitude 9.2: The 1964 Great Alaska Earthquake is a short video relating how the largest quake in U.S. history had profound and lasting impacts on our lives. The video features USGS geologist George Plafker who, in the 1960's, correctly interpreted the quake as a subduction zone event.

Communications and Publishing

USGS Damage from the magnitude 9.2 earthquake in Alaska 

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

#### USGS Damage from the magnitude 9.2 earthquake in Alaska 

link

Damage from the magnitude 9.2 earthquake in Alaska on March 27, 1964.

Earthquake Hazards

Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

August 12, 2022

####   Massive Volcanic Eruption and Tsunami Informs Plan for Future Eruptions, Sea-level Rise

Between January 14-15, 2022, volcanic explosions destroyed much of Hunga Tonga-Hunga Ha'apai, an uninhabited island in the Tonga archipelago in the...

Read Article

The temblor that changed earthquake science turns 30

June 22, 2022

####   The temblor that changed earthquake science turns 30

To mark the 30th anniversary of a Southern California earthquake, we’ll note why it was significant and listen to USGS employees share their own quake...

Read Article

Volcanoes and USGS Volcano Science: Just the Facts

April 12, 2022

####   Volcanoes and USGS Volcano Science: Just the Facts

Volcanoes are an incredible feature of Earth’s geologic environment – at once awe-inspiring and terrifying. They remind us that the planet we call...

Read Article

Take a Tour of the Earthquake Hazards Program Site

March 18, 2022

####   Take a Tour of the Earthquake Hazards Program Site

Or...How to Find USGS Earthquake Information Quickly!

Read Article

The largest landslide in the world

November 22, 2021

####   The largest landslide in the world

Yellowstone is well-known as one of the largest volcanic systems in the world. Few people know, however, that the largest-known subaerial landslide on...

Read Article

10-Year Anniversary of US’s Most Widely Felt Earthquake

August 4, 2021

####   10-Year Anniversary of US’s Most Widely Felt Earthquake

Ten years ago, in the early afternoon of August 23, 2011, millions of people throughout the eastern U.S. felt shaking from a magnitude 5.8 earthquake...

Read Article

Post-wildfire Landslides Becoming More Frequent in Southern California

February 25, 2021

####   Post-wildfire Landslides Becoming More Frequent in Southern California

Southern California can now expect to see post-wildfire landslides occurring almost every year, with major events expected roughly every ten years, a...

Read Article

Mount St. Helens’ 1980 Eruption Changed the Future of Volcanology

May 14, 2020

####   Mount St. Helens’ 1980 Eruption Changed the Future of Volcanology

If scientists armed with today's monitoring tools and knowledge could step back in time to the two months before May 18, 1980, they would have been...

Read Article

The Complex Dynamics of Geyser Eruptions

May 10, 2017

####   The Complex Dynamics of Geyser Eruptions

Despite two centuries of scientific study, basic questions persist about geysers—why do they exist? What determines their behavior?

Read Article

Northern Alaska Coastal Erosion Threatens Habitat and Infrastructure

July 1, 2015

####   Northern Alaska Coastal Erosion Threatens Habitat and Infrastructure

Read Article

link

####                 What is an earthquake and what causes them to happen?              

An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel. In California there are two plates - the Pacific Plate and the North...

link

####   What is an earthquake and what causes them to happen?

An earthquake is caused by a sudden slip on a fault. The tectonic plates are always slowly moving, but they get stuck at their edges due to friction. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth's crust and cause the shaking that we feel. In California there are two plates - the Pacific Plate and the North...

Learn More

link

####                 What is liquefaction?              

Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the...

link

####   What is liquefaction?

Liquefaction takes place when loosely packed, water-logged sediments at or near the ground surface lose their strength in response to strong ground shaking. Liquefaction occurring beneath buildings and other structures can cause major damage during earthquakes. For example, the 1964 Niigata earthquake caused widespread liquefaction in Niigata, Japan which destroyed many buildings. Also, during the...

Learn More

link

####                 What is a landslide and what causes one?              

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material...

link

####   What is a landslide and what causes one?

A landslide is defined as the movement of a mass of rock, debris, or earth down a slope. Landslides are a type of "mass wasting," which denotes any down-slope movement of soil and rock under the direct influence of gravity. The term "landslide" encompasses five modes of slope movement: falls, topples, slides, spreads, and flows. These are further subdivided by the type of geologic material...

Learn More

link

####                 How Do Volcanoes Erupt?              

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. The...

link

####   How Do Volcanoes Erupt?

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. The...

Learn More