1. Volcanoes: Volcanoes are common at both convergent and divergent plate boundaries.
* Convergent boundaries: When oceanic and continental plates collide, the denser oceanic plate subducts (slides) beneath the continental plate. As the oceanic plate sinks, it melts, and the molten rock rises to the surface, forming volcanoes. Examples include the Andes Mountains and the Cascade Range in North America.
* Divergent boundaries: At mid-ocean ridges, where plates move apart, magma rises from the mantle to create new oceanic crust. This process often results in underwater volcanoes that can eventually rise above sea level, forming volcanic islands. Examples include Iceland and the Galapagos Islands.
2. Earthquakes: Earthquakes are most common at transform and convergent plate boundaries.
* Transform boundaries: At transform boundaries, plates slide horizontally past each other. This movement is not always smooth, and can cause rocks to break and slip, resulting in earthquakes. A famous example is the San Andreas Fault in California.
* Convergent boundaries: At convergent boundaries, the collision of plates can cause stress and pressure that builds up over time. When this pressure is released, it can cause earthquakes. Examples include the Himalayan mountain range and the Pacific Ring of Fire.
