Data from the Global Volcanism Program of the Smithsonian Institution
Details for: Okmok
The broad, 35-km-wide Okmok shield volcano is truncated by two spectacular, largely overlapping, 10-km-wide calderas. Both calderas at this dominantly basaltic volcano were formed by voluminous eruptions of dacitic tephra and pyroclastic flows during the Holocene, one about 8250 years ago and the other about 2400 years ago. Numerous satellitic pyroclastic cones and lava domes dot the floor of the caldera and the flanks of the volcano. Explosive eruptions and lava flows have originated from cones within the caldera in historical time. Photo by John Reeder (Alaska Division of Geological & Geophysical Surveys).
Volcano Number:311290
Volcano Name:Okmok
Country:United States
Volcano Type:Shield
Last Eruption:2008 CE
Elevation:1073m
Tectonic Setting:Subduction zone / Intermediate crust (15-25 km)
Pop. within 5km:0
Pop. within 10km:0
Pop. within 30km:0
Pop. within 100km:4
Latitude:53.43
Longitude:-168.13



Eruption Data from the Global Volcanism Program of the Smithsonian Institution
Volcano Number Volcano Name Eruption Number Activity Type Explosivity Index Max Explosivity Index Modifier Activity Area Activity Unit Start Evidence Method Start Date End Date
311290 Okmok 19833 Confirmed Eruption 4 P Radiocarbon (uncorrected) -6310
311290 Okmok 19834 Confirmed Eruption 6 Okmok II caldera Radiocarbon (uncorrected) -100
311290 Okmok 19835 Confirmed Eruption Historical Observations 1805
311290 Okmok 19836 Confirmed Eruption 3 Cone E? or B? Historical Observations 1817/3/1 1820
311290 Okmok 19837 Confirmed Eruption Cone B? Historical Observations 1824 1830
311290 Okmok 19839 Confirmed Eruption 2 ? Cone A? Historical Observations 1878
311290 Okmok 19840 Confirmed Eruption 3 SW part of caldera (Cone A) Historical Observations 1899
311290 Okmok 19841 Confirmed Eruption 2 Cone A? Historical Observations 1931/3/21 1931/5/13
311290 Okmok 19842 Uncertain Eruption SW part of caldera (Cone A) 1936
311290 Okmok 19843 Confirmed Eruption SW part of caldera (Cone A) Historical Observations 1938
311290 Okmok 19844 Confirmed Eruption 1 SW part of caldera (Cone A) Historical Observations 1943
311290 Okmok 19845 Confirmed Eruption 2 SW part of caldera (Cone A) Historical Observations 1945/6/4 1945
311290 Okmok 19846 Confirmed Eruption 3 SW part of caldera (Cone A) Historical Observations 1958/8/14 1958/8/25
311290 Okmok 19847 Confirmed Eruption 3 SW part of caldera (Cone A) Historical Observations 1960/10/15 1961/4/15
311290 Okmok 19848 Confirmed Eruption 3 ? SW part of caldera (Cone A) Historical Observations 1981/3/24 1981/3/24
311290 Okmok 19849 Confirmed Eruption 2 SW part of caldera (Cone A) Historical Observations 1983/7/8 1983/7/8
311290 Okmok 19850 Confirmed Eruption 2 SW part of caldera (Cone A) Historical Observations 1986/11/18 1988/2/26
311290 Okmok 19851 Confirmed Eruption 3 SW part of caldera (Cone A) Historical Observations 1997/2/11 1997/5/19
311290 Okmok 19852 Confirmed Eruption 4 ? NE caldera floor Historical Observations 2008/7/12 2008/8/19
Emissions Data from the Global Volcanism Program of the Smithsonian Institution
Emission ID SO2 Kilotons Start Date End Date
214 150 2008/07/12 2008/07/12


Data from the Earthchem Library
Title Author Release Date DOI Link
The emissions of CO2 and other volatiles from the world’s subaerial volcanoes The emissions of CO2 and other volatiles from the world’s subaerial volcanoes Fischer, Tobias 2020-11-21 10.1594/IEDA/111445 Details
Field Report for the Collection of Mafic Tephra from the Aleutians Islands between Unimak and the Island of Four Mountains (Alaska, USA) Plank, Terry 2020-06-23 10.26022/IEDA/111584 Details
Data from the Earthchem Portal


Data from the SESAR Database


Data from the MaGa Database
Sorry. No data exist for this volcano in the MaGa database.