Bobrof Island

Because of the inclusion of Alaska, the United States has the largest number of active volcanoes in the world, many of them geologically young.[6] In Alaska, at least 50 volcanoes, including those in the Aleutian archipelago, have erupted in historical time.[7] Alaska accounts for about 80% of the United States' volcanoes, excluding the seamounts in the area, about 8% of the world's volcanoes, and most of these are located among the Aleutian Islands.[7] The Aleutian Islands arc forms the northern boundary of the Pacific Ring of Fire,[7] where tectonic activity generates earthquakes and volcanic eruptions regularly.

The volcano is thought to be of Holocene age.[4] Though no historical eruptions have taken place at Bobrof, it has erupted at least once. This data can be confirmed through pyroclastic flow deposits containing andesite.[4] Once these flows were studied, at a building intended for earthquake monitoring, they confirmed that Bobrof was prone to explosive activity.[8] There are lava deposits on the mountain which also suggest activity similar to shield eruptions.[8] In collected samples, there are traces of basaltic andesite and dacite.[9] No complete publications exist for Bobrof's definite geology, just those with facts and some information.[9]