Giant eruptions can literally affect the whole world.
On the other hand, small eruptions may affect only a single hillside or valley. Let's look at the characteristics and effects of volcanic eruptions of different sizes, starting with small and working our way up. A small volcanic eruption may consist of a single small burst of steam and volcanic ash, such as the initial eruption of Mount St. Helens, or a single lava flow like those that make the local evening news in Hawaii. By exercising some caution, you can view many small eruptions from a reasonable distance. It all depends on the type of eruption.