Introduction

Most of the time, we go about our daily lives completely unaware that underneath our feet lies a great and powerful force. Earth's extremely hot interior is constantly interacting with the cooler crust at the surface. Yet, when a massive volcano erupts, spewing glowing ash into the sky, or an earthquake tears through a city, collapsing buildings, the world becomes aware of Earth’s immensely powerful force.
Earth's hot interior also hides some fantastic gems. Some volcanoes stay hidden under sheets of ice, at the bottom of the sea, and even in our own national parks. Faults may lie silently in our backyards and cities until they finally release a massive amount of energy.
Exposed magma glows along the seafloor of the Pacific Ocean.
(NSF/NOAA)

Explore All the Different Types of Boundaries

Earth’s outermost, rigid layer includes more than a dozen slabs of rock, called tectonic plates. Each of these tectonic plates is slowly and constantly moving. Many times, fascinating geologic events such as volcanoes, earthquakes and faults occur at plate boundaries, or where one tectonic plate meets another.

Other geologic events may occur unexpectedly, far from plate boundaries, happening in the interior of a tectonic plate.

Explore all of these fascinating locations to learn more about Earth’s hidden wonders.

Divergent
Convergent
Convergent with subduction
Transform
At divergent plate boundaries, tectonic plates move away from one another. When plates move apart, lava and magma rise to the surface and make new rock. This type of boundary may result in the formation of small volcanoes, shield volcanoes and rift valleys.
This map shows the types and locations of tectonic plate boundaries around the world.
Hot lava flows from the eruption of the Tolbachik volcanic complex in Eastern Russia.
(Budkov Denis)
Select a location to explore Earth's Hidden Wonders.

Tamu Massif

A Giant in the Deep

Investigate the largest volcano on Earth hidden far beneath the ocean.

Explore

The Mid-Atlantic Ridge

40,000 Mile Long Volcano

Investigate mid-ocean ridges and the fascinating life that thrives in this environment.

Explore

San Andreas Fault

Shake Alert

Investigate how technology is providing warning to residents living along the San Andreas Fault.

Explore

Maar Volcanoes

Unexpected Eruptions

Investigate one of the most unpredictable types of volcanoes in the world.

Explore

Fire Under the Ice

Volcanoes in West Antartica

Investigate how scientists detected potentially active volcanoes underneath sheets of ice in Antarctica.

Explore

Yellowstone

A Sleeping Supervolcano

Investigate the volcano lurking underneath one of the most popular national parks in the United States.

Explore
  • anomaly

    noun

    Something that is unexpected, abnormal, or differing from what is common.

  • crater

    noun

    A bowl-shaped hole in Earth's surface.

  • earthquake

    noun

    A sudden shaking of the ground producing seismic waves or vibrations, which may result in destruction. An earthquake occurs when slabs of rock suddenly slip past each other at a break in Earth's crust, called a fault.

  • geyser

    noun

    A type of hot spring that sends heated water and steam up into the air.

  • lava

    noun

    Hot, molten rock that has reached Earth's surface through volcanic eruption or a crack in the crust.

  • mid-ocean ridge

    noun

    A long line of mountains on the seafloor, formed by divergent plate boundaries and the upwelling of magma. Seismic and volcanic activity are common along these regions.

  • seismometer (or seismograph)

    noun

    A tool to measure the movement of the ground. This instrument can measure seismic activity, such as the force and duration of an earthquake.

  • tectonic plate

    noun

    Large, slowly moving, slab of solid rock that make up Earth's crust.

  • convergent boundary

    noun

    A location where tectonic plates collide with each other. When two continental plates push toward each other, they fold together and form mountain ranges.

  • crust

    noun

    The outermost layer of Earth. The crust is the coolest and thinnest layer of Earth, ranging from about 5 to 70 km thick. The crust is divided into large slabs of rock, called tectonic plates.

  • eruption

    noun

    Molten rock, ash, and steam ejected from a volcano or geyser.

  • horizontal

    adjective

    At a right angle to the vertical or parallel to the ground level.

  • maar

    noun

    A broad volcanic crater typically filled with water. Maars are created from the explosion that occurs when groundwater meets hot magma.

  • p-wave

    noun

    A type of seismic wave, called primary waves, because they are the first waves from an earthquake to reach a seismograph. P-waves are compressional waves, shaking the ground back and forth, towards and away from the direction the wave is traveling.

  • steam

    noun

    Water in the gas phase.

  • transform boundary

    noun

    A location where tectonic plates slide horizontally past one another. The plates grind together causing frequent earthquakes.

  • convergent with subduction boundary

    noun

    At convergent plate boundaries with subduction, plates push together, and one plate moves underneath the other. This type of boundary may result in the formation of trenches, volcanoes, islands, and earthquakes, which can trigger tsunamis.

  • divergent boundary

    noun

    A location where tectonic plates move away from one another. When plates move apart, lava and magma rise to the surface and make new rock. This type of boundary may result in the formation of small volcanoes, shield volcanoes and rift valleys.

  • fault

    noun

    A fracture or crack in the rocks that make up Earth's crust.

  • hydrothermal vent

    noun

    An opening in the sea floor where magma meets water. This interaction causes heated water, filled with minerals, to rise up from the opening.

  • magma

    noun

    Hot liquid or molten rock located beneath the surface of Earth.

  • seismic wave

    noun

    The vibration from an earthquake that travels within Earth or along Earth's surface.

  • s-wave

    noun

    A type of seismic wave, called shear waves or secondary waves, because they reach a seismograph and shake the ground second, after an earthquake occurs. S-waves shake the ground perpendicularly to the direction the waves are traveling.

  • volcano

    noun

    An opening in Earth's crust which releases hot gases and molten rock.