Asamayama is a complex volcano located in Japan at an elevation of 2,568 meters in a subduction zone and continental crust tectonic setting (greater than 25 km depth). According to the Smithsonian Global Volcanism Program, the official record documents 129 confirmed eruptions spanning a vast timeline from prehistoric isotopic evidence up to modern historical observations.
The earliest recorded activity in the database dates back to 7200 BCE, determined through calibrated carbon-14 isotopic evidence with a start-year uncertainty of 200 years. Throughout the millennia, recorded eruptive episodes vary significantly in scale, frequency, and observation method, transitioning from ancient geological records to detailed historical reports.
Chronological Distribution of Eruptions
Volcanic activity at Asamayama has been documented across multiple centuries and millennia, with varying frequencies recorded in the official dataset. The distribution reflects both the long-term geological history of the volcano and the increasing detail of human historical observations over time.
Century-by-century breakdown of confirmed eruptions in the official record:
- 72nd century BCE: 1 eruption (starting around 7200 BCE)
- 64th century BCE: 1 eruption
- 47th century BCE: 1 eruption
- 41st century BCE: 1 eruption
- 35th century BCE: 1 eruption
- 26th century BCE: 1 eruption
- 12th century BCE: 1 eruption
- 4th century CE: 1 eruption
- 7th century CE: 1 eruption
- 12th century CE: 1 eruption (including the large VEI 5 eruption of August–October 1108)
- 16th century CE: 12 eruptions
- 17th century CE: 20 eruptions (including activity on November 25, 1655)
- 18th century CE: 28 eruptions (including activity spanning July to August 1755)
- 19th century CE: 12 eruptions
- 20th century CE: 41 eruptions
- 21st century CE: 6 eruptions
Notable Recorded Eruptions
While the database contains 129 confirmed eruptions, Volcanic Explosivity Index (VEI) ratings are available for 121 of them. The largest recorded eruption in the dataset reached a VEI of 5.0, which occurred from August 29 to October in the year 1108, documented via reported observations.
Subsequent historical centuries show frequent activity, such as a VEI 2 eruption starting on November 25, 1655, and a VEI 2 eruption lasting from July 5 to August 6, 1755. In the modern era, Asamayama has continued to exhibit documented activity; a confirmed eruption occurred from August 7 to August 25, 2019, carrying a VEI of 2 and recorded through direct observations.
The profile's last known eruption year is recorded as 2019, corresponding to the August 2019 activity.
Sources and further context
Official datasets support the event-specific facts.