Akutan is a stratovolcano located in the United States, standing at an elevation of 1,303 meters within a subduction zone setting characterized by intermediate crust (15 to 25 kilometers depth). According to the Smithsonian Global Volcanism Program's official record, Akutan has a documented history comprising 40 confirmed eruptions. These events span a vast chronological range, beginning with an early isotopic-dated eruption around 7620 BCE and extending to the latest recorded eruption on December 18, 1992 CE.
Chronological Distribution of Eruptions
The historical and pre-historical record of Akutan features varying concentrations of activity across different centuries and millennia. The Smithsonian records indicate confirmed eruptions across multiple distinct periods, shifting from ancient radiocarbon-dated events to modern observational accounts:
- 77th century BCE: 1 confirmed eruption (starting around 7620 BCE, with a 300-year uncertainty range)
- 42nd century BCE: 1 confirmed eruption
- 6th century CE: 1 confirmed eruption
- 4th century CE: 1 confirmed eruption (noted with a Volcanic Explosivity Index of 5.0)
- 15th century CE: 1 confirmed eruption
- 19th century CE: 9 confirmed eruptions
- 20th century CE: 26 confirmed eruptions
Evidence Methods and Intensity
The record for Akutan relies on a combination of scientific dating techniques and direct human observation. Early events are primarily reconstructed using isotopic methods such as calibrated and uncalibrated carbon-14 dating. Later events, particularly those occurring through the 19th and 20th centuries, are documented through direct reporting and observation.
Where measured, the Volcanic Explosivity Index (VEI) provides a relative scale for the size of explosive events. Across Akutan's confirmed history, 31 eruptions have associated VEI values recorded. The largest recorded eruption reached a VEI of 5.0, which occurred during the 4th century CE. Subsequent historical eruptions generally featured lower index values, such as the 1946–1947 event which recorded a VEI of 2.0, and the December 18, 1992 eruption which registered a VEI of 1.0.
Frequently asked questions
How many eruptions has Akutan had?
Akutan has 40 confirmed eruptions recorded in the official Smithsonian Global Volcanism Program database.
When was Akutan's earliest recorded eruption?
The earliest recorded eruption in the official record dates back to 7620 BCE, determined through calibrated isotopic methods.
When was Akutan's latest recorded eruption?
The latest recorded eruption occurred on December 18, 1992.
What was the largest eruption recorded at Akutan?
The largest recorded eruption at Akutan reached a Volcanic Explosivity Index (VEI) of 5.0, occurring in the 4th century CE.
Image credits
- Beverly Bennett Dobbs — Wikimedia Commons source — Public domain
Sources and further context
Official datasets support the event-specific facts.