100 BC Eruption of Okmok

Name: 100 BC Eruption of Okmok
Location: Okmok, United States

100 BC · VEI 6

Okmok in the United States erupted in 100 BC with a Volcanic Explosivity Index of 6.

Where it erupted

Okmok, United States, with its other significant eruptions.

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The eruption

Date: 100 BC
Volcano: Okmok, shield volcano
Country: United States
Volcanic Explosivity Index: 6, paroxysmal (eruption column over 25 km)
Location: 53.430° N, 168.130° W

The toll

The record gives no deaths, injuries or damage for this eruption.

What the record says

NCEI’s account, from the sources it cites.

The 2050+/50 BP collapse of Okmok caldera generated pyroclasts that spread over 1,000 km2 on Umnak Island. The central vent eruption the generated a Tsunami (giant sea waves) associated with caldera collapse.

Other significant eruptions of Okmok

August 29, 1878VEI 2 · tsunami

Every eruption in 100 BC The 100s BC Okmok Earthquakes near Okmok

Sources

Volcanoes and significant eruptions from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. Volcano numbers are the Smithsonian Institution’s Global Volcanism Program’s. NCEI event 5225.