Bezymianny Volcano Is Nearly Rebuilt — Eruptions Are Restoring Its Lost Summit

A restless Bezymianny volcano on Russia's Kamchatka Peninsula sent an ash column roughly 32,800 feet (10 kilometers) into the sky in late November, underscoring the mountain's ongoing recovery from a catastrophic 1956 collapse.

Before the collapse on March 30, 1956, Bezymianny rose at least 10,213 feet (3,113 meters) above sea level. That eruption removed a large part of the volcano's flank, converting the cone into a horseshoe-shaped amphitheater and destroying the summit. Almost immediately afterward, a lava dome began to form within the amphitheater, and the mountain has been rebuilding ever since.

The lava dome began growing shortly after the eruption, pictured here in 1988. | Credit: Photo by Alexander Belousov, 1988 (Institute of Volcanology, Kamchatka, RussiaCreative Commons BY-NC 4.0).

How the Volcano Has Regrown

Researchers at the Institute of Volcanology and Seismology in Kamchatka (Russian Academy of Sciences) used field observations, webcams, aerial photography and satellite data to track Bezymianny's recovery. A 2020 analysis comparing aerial photographs from 1949 to 2017 found that the volcano has nearly regained its former height. From 1956 through 2017, the study estimated an average accumulation of about 932,307.2 cubic feet (26,400 cubic meters) of rock per day.

The rebuilding has involved both explosive eruptions and effusive activity. Explosive events typically occur a couple of times per year on average, producing ash plumes and pyroclastic flows. Effusive eruptions — relatively non-explosive lava flows that were first clearly recorded at Bezymianny in 1977 — have produced layered, lower-silica lava that is less viscous and able to pile up and reshape the cone.

Bezymianny (pictured here in 2017) is expected to reach its pre-1956 eruption height in the next five to 10 years. | Credit: Alexandr Piragis/Getty Images

Hazards and Monitoring

Late-November activity produced a towering ash column and hot avalanches of gas and rock (pyroclastic flows), according to the Smithsonian's Global Volcanism Program. As the cone approaches its pre-collapse summit level, scientists are particularly focused on slope stability. Researchers Alexander Belousov and Marina Belousova note that volcanic edifices rebuilt inside horseshoe-shaped craters can be vulnerable to another large-scale collapse, which could trigger a major explosive eruption.

"The most surprising thing was the fast growth of the new volcanic edifice," Belousov and Belousova told Live Science, emphasizing the value of a long-term dataset for forecasting the behavior of other collapsed-and-regrown volcanoes.

Ongoing monitoring combines ground-based fieldwork, continuous webcam feeds, observation flights and satellite imagery. While each volcano follows its own path, Bezymianny's recovery offers an important comparative case — similar collapse-and-regrowth cycles have been observed at other volcanoes such as Mount St. Helens in the United States.

Outlook: The 2020 study projected that Bezymianny could reclaim its pre-1956 elevation sometime between 2030 and 2035 if current growth trends continue. Scientists warn that continued monitoring is essential to anticipate potential slope failures and large explosive events as the cone rebuilds.