Tectonics of the East Pacific

As you cruise past the majestic Andes, take a moment to thank the tectonic plates for their existence.

CAROLYN BEASLEY

5 min read

A volcano in the Aleutian Islands, Alaska. There are 40 active volcanoes in the Aleutian Islands. Photo: Shutterstock

A volcano in the Aleutian Islands, Alaska. There are 40 active volcanoes in the Aleutian Islands. Photo: Shutterstock

An illustration of two plates sliding towards each other, forming a convergent plate boundary, which can result in new magma rising and erupting violently. Photo: Shutterstock

An illustration of two plates sliding towards each other, forming a convergent plate boundary, which can result in new magma rising and erupting violently. Photo: Shutterstock

A mountain range in southwest Alaska. Photo: Shutterstock

A mountain range in southwest Alaska. Photo: Shutterstock

Mountains of the deep

Tectonic movements also generate mountains we can’t see. If your expedition cruise takes you to the east Pacific, you may sail over the East-Pacific Rise. This is part of the world's largest mountain range – the Mid-Ocean Ridge System – which is mostly underwater and stretches over 64,000 kilometres. This is an example of a divergent tectonic boundary, where the plates pull apart from one another and magma pushes upwards through the gap before cooling to form a rocky ridge.

The third type of tectonic boundary in the east Pacific region is the transform boundary, which is caused when two plates grind past each other horizontally in opposite directions. As they jam together, the plates accumulate tension that is suddenly released as earthquakes. Where these slips occur, we have active fault lines like the San Andreas Fault in California.

A mid-ocean ridge is a seafloor mountain system, where seafloor spreading takes place along a divergent plate boundary.

1. The Andes

Photo: Shutterstock

Photo: Shutterstock

2. The Aconcagua

Photo: Shutterstock

Photo: Shutterstock

3. The Peru-Chile trench

Photo: Shutterstock

Photo: Shutterstock

4. Aleutian Islands

Photo: Shutterstock

Photo: Shutterstock

5. East-Pacific Rise

Divergence occurs when two plates pull apart. Photo: Shutterstock

Divergence occurs when two plates pull apart. Photo: Shutterstock

6. San Andreas Fault

Photo: Shutterstock

Photo: Shutterstock