There is no definitive evidence that an eruption at one volcano can trigger an eruption at a volcano that’s hundreds of kilometers/miles away or on a different continent.
There are a few historic examples of simultaneous eruptions from volcanoes (or volcanic vents) located within about 10 kilometers (6 miles) of each other, but it's difficult to determine whether one eruption caused the other.
- Volcanoes that share common magma reservoirs can sometimes trigger unrest at each other. The 1912 eruption of Alaska’s Novarupta volcano (the largest eruption of the 20th century) was fueled by magma that came from a magma reservoir beneath Mount Katmai, 10 kilometers (6 miles) away. Mount Katmai did not erupt, but after the eruption of Novarupta, Mount Katmai collapsed into the emptied magma chamber below it.
- Some individual volcanoes or vents are considered to be part of a larger volcano complex. In some such cases, one eruption doesn’t really "trigger" a nearby vent to erupt, but moving magma finds its way to the surface at multiple sites. For example, Tavurvur and Vulcan cones are vents within Rabaul Caldera in Papua New Guinea that erupted at nearly the same time in 1994.
However, not all nearby volcanoes show this behavior. Hawaii’s Kilauea volcano is located on the flank of Mauna Loa volcano, so the two are only 33 kilometers (20 miles) apart, yet those two volcanoes have distinctly different magma reservoirs. Despite their proximity, an eruption at one does not appear to trigger an eruption at the other.
Learn more: USGS Volcano Hazards Program