Tectonic Hazards - Plate Tectonics

Think of Earth like a giant layered cake with four main sections. The crust (where we live) sits on top of the mantle, which covers the outer core and inner core. The crust and upper mantle form the lithosphere - basically Earth's rocky shell that's cracked into huge pieces called tectonic plates.

These tectonic plates are like enormous puzzle pieces that make up either continents or ocean floors. Continental crust is thick $30-100km$, light, and made of granite - it's flexible and won't sink. Oceanic crust is much thinner $5-10km$, denser, and made of basalt - this type can be forced downward when plates collide.

The plates don't just sit there - they're constantly moving thanks to convection currents. Heat from Earth's core warms the mantle, creating currents that drag the plates along at the same speed your nails grow. When these moving plates meet, you get plate boundaries or margins.

Key Point: There are three main types of plate boundaries, each creating different geological features and hazards.

Constructive boundaries occur when plates move apart. Magma pushes through the gap, causing earthquakes and creating shield volcanoes like those forming Iceland. Destructive boundaries happen when plates collide - the denser oceanic plate gets forced under the continental plate in a process called subduction. This creates violent, explosive volcanic eruptions and strong earthquakes as the plates grind together.