1. Mount St. Helens, USA (1980): This eruption, which occurred on May 18, 1980, was one of the most significant in recent U.S. history. It was a massive, explosive eruption that resulted in a significant loss of life (57 deaths), destroyed over 200 homes, and caused widespread environmental damage. The eruption was preceded by a series of earthquakes and steam explosions, and ultimately resulted in a massive landslide and a towering ash plume.

2. Mount Pinatubo, Philippines (1991): This eruption, occurring in June 1991, was the second largest volcanic eruption of the 20th century. It caused a massive ash cloud that affected global temperatures and had a significant impact on the environment. The eruption also displaced thousands of people and caused significant agricultural damage.

These are just two examples of many significant volcanic eruptions in the last 100 years. Other notable eruptions include:

* Krakatoa, Indonesia (1883): While not within the last 100 years, it is still notable for its massive impact and its influence on the study of volcanology.

* Nevado del Ruiz, Colombia (1985): This eruption melted glaciers and caused a deadly mudflow (lahar) that killed over 23,000 people.

It's important to remember that volcanic eruptions can have devastating consequences, but also play a crucial role in shaping our planet.