Ring of Fire: What Happens If the Volcanoes Erupt?

The Ring of Fire is a vast horseshoe-shaped network of volcanoes that encircles the Pacific Ocean, stretching over 25,000 miles.

It’s not a continuous “belt,” but rather a series of boundaries between the tectonic plates that make up the Earth’s crust.

On a global scale, the phrase “On solid ground” is actually a misnomer.

Tectonic plates are enormous, irregular slabs of solid rock that comprise the planet’s outer shell, and they’re in constant motion.

There are two main types of crust that make up tectonic plates, which can be hundreds or thousands of miles in size and around 20 to 100 miles thick.

• Oceanic crust that’s relatively thin, and typically made up of basaltic rocks. 

• Continental crust is typically thicker, less dense, and composed primarily of granitic rocks. 

Plates of each type float on a hotter, more malleable “upper mantle” of the Earth called the asthenosphere.   

Tectonic plates typically shift and move on the asthenosphere very slowly — far too gradually to be perceptible by humans — but enough to reshape the Earth’s surface over millions of years.

Despite typically moving in slow motion, shifts and interactions between tectonic plates also cause earthquakes, volcanic eruptions, and even the formation of lakes, oceans, and mountain ranges.

Plate tectonic boundaries are classified into three main categories:

• Convergent boundaries are areas where two tectonic plates are moving towards each other. What happens when they collide depends primarily on the types of crust.

  • Oceanic-Continental Convergence: The denser ocean crust bends and slides under the lighter continental plate, resulting in subduction. Subduction often creates deep ocean trenches and a chain of coastal volcanoes like the Andes Mountains.

  • Oceanic-Oceanic Convergence: Two oceanic plates converge with one subducting the other, resulting in a deep trench and a curved chain of volcanic islands, like the Mariana Islands.

  • Continental-Continental Convergence: Subduction is unlikely. Instead, the plates collide and force the crust upwards, creating enormous mountain ranges like the Himalayas.

• Divergent Boundaries are areas where two plates are moving apart. Magma from the asthenosphere rises to the surface, and new crust is formed as the plates separate. A divergent boundary between tectonic plates formed the Mid-Atlantic Ridge, a massive underwater mountain range.

• Transform Boundaries are the most well-known and potentially destructive of plate tectonic boundaries. For example, the San Andreas Fault, frequently cited as the most likely culprit of causing the Big One in California, is a transform boundary. Plates slide horizontally past one another at transform boundaries, neither creating new nor consuming old crust. Instead, the tectonic plates grind together, often resulting in seismic events and sometimes in catastrophic earthquakes.