6. 28 March 1982 EL Chichon Mexico
El Chichon faced the largest deadliest eruption in the modern history of Mexico where almost 2,000 people were killed and lost their life. According to the Wikipedia these volcanic eruptions affected over 24,000 km area and the land covered by this incident in dept was around 40 cm.
This eruption changed the climate of EL Chichon badly as this area did not see any cooling after this incident. Many geologists already warned before this eruption but the Gov did show the lack of preparation.