Lakagigar

Lakagigar (Craters of Laki) is a volcanic fissure in the south of Iceland, not far from the canyon of Eldgja and the small village of Kirkjubaejarklaustur.
The system erupted violently over an eight-month period between June 1783 and February 1784 from the Laki fissure, which was 25km long, pouring out an estimated 14 cubic kilometers of basalt lava and clouds of poisonous hydro uoric acid and sulfur dioxide compounds that contaminated the soil. This lead to the death of over 50% of Iceland's livestock population, and the destruction of the vast majority of all crops. This resulted in a famine which then killed approximately 25% of the island's human population. The lava flows destroyed 20 farms.
The Laki eruption and its aftermath caused a drop in global temperatures, as 120 million tons of sulfur dioxide was spewed into the Northern Hemisphere. This caused crop failures in Europe and may have caused droughts in North Africa and India.
The destructive force of the eruption, also known as the Skaftareldar (Skaftafires), is nowadays not seen anymore, because the lava formations are covered in soft green moss.