Here's why:

* Rapid onset: Volcanic eruptions can happen very quickly, sometimes with little to no warning.

* Significant changes: They drastically alter the landscape, spewing out lava flows, ash clouds, and gases in a short timeframe.

* Instantaneous impact: Eruptions can cause immediate and devastating effects, such as destruction of property, loss of life, and disruption of ecosystems.

Other examples of sudden geologic processes include:

* Earthquakes: These can occur within seconds and cause massive ground shaking, tsunamis, and landslides.

* Landslides: While some landslides are slow-moving, others can happen suddenly and dramatically due to heavy rainfall, earthquakes, or volcanic activity.

* Meteorite impacts: These are extremely rare but can create massive craters and have significant global impacts.

These processes highlight the dynamic and often unpredictable nature of Earth's geology.