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Mauna Kea Volcano | Dr John Seach
Last updated: January 2026
Big Island, Hawaii
19.82 N, 155.47 W
summit elevation 4205 m
Dormant shield volcano
Mauna Kea is the second highest volcano in the Pacific and the tallest mountain on Earth when measured from its seafloor base (>10,000 m). It is a dormant volcano with a small possibility of future eruptions. Eighty percent of people who summit Mauna Kea suffer from altitude illness due to rapid ascent from sea level.
The irregular topography of the upper slopes of Mauna Kea contrasts with the smoother profile of Mauna Loa volcano.
Warning: Rapid ascent to high altitude (>4000 m) commonly causes acute mountain sickness (headache, nausea, fatigue). Descent recommended if symptoms appear. Cold temperatures, strong winds, and thin air at summit pose risks; proper preparation essential.
Geology and Volcanology
Mauna Kea is a post-shield stage basaltic shield volcano in the Hawaiian hotspot chain. It features numerous cinder cones on upper flanks and no summit caldera. Last eruptions ~4500 years ago produced hawaiite lavas. Currently dormant with persistent fumarolic activity absent. Summit hosts world-class astronomical observatories due to clear skies and minimal light pollution. Monitored by HVO for seismic unrest indicating possible reactivation.
Current Activity (January 2026)
Mauna Kea remains dormant with no eruptive activity for ~4500 years. Low seismicity and stable deformation. No fumarolic emissions. Summit access open but altitude risks remain. Monitoring by HVO ongoing; small chance of future eruption.
Mauna Kea volcano photos by Dr John Seach
Mauna Kea Volcano from Hilo
Dr John Seach at summit of Mauna Kea volcano
Mauna Kea volcano, Hawaii
Mauna Kea Volcano - Dr John Seach
Canada-France-Hawaii Telescope (L)
Gemini North Telescope (R)
2011 Earthquakes
A series of earthquakes occurred under Mauna Kea volcano in Hawaii on 19th October 2011. The largest earthquake was magnitude 4.5 and had a focus at a depth of 18 km at a location 9 km NE of the summit.
1973 Earthquakes
On 26th April 1973 a magnitude 6.2 earthquake occurred 15 km north of Hilo, Hawaii, at a focal depth of 48 km. The location was beneath the east flank of Mauna Kea, a volcano dormant historically, but active within the last 4000 yr. Aftershocks were restricted to a depth of 55-35 km. The earthquakes were not related to volcanic activity at Mauna Loa and Kilauea volcanoes, and may indicate a deep seated prelude to a resumption of activity at Mauna Kea.
Snow on Mauna Kea
There are seasonal snow falls on Mauna Kea volcano, with depths up to a few metres.
Mauna Kea Observatory
Mauna Kea Observatory houses the world's largest observatory for optical, infrared, and submillimeter astronomy. Telescopes are operated by astronomers from eleven countries. Major instruments on the mountain include Keck Observatory, Subaru Telescope, Gemini Northern Telescope, United Kingdom Infrared Telescope, Canada-France-Hawaii Telescope, NASA Infrared Telescope Facility, UH 2.2-m telescope, Caltech Submillimeter Observatory, James Clerk Maxwell Telescope, Submillimeter Array, and Very Long Baseline Array.
Further reading
Wolfe, E.W. et al., 1997. The geology and petrology of Mauna Kea Volcano, Hawaii; a study of postshield volcanism. U.S. Geological Survey Professional Paper 1557.
Frey, F.A. et al., 1991. The evolution of Mauna Kea volcano, Hawaii: petrogenesis of tholeiitic and alkalic basalts. Journal of Geophysical Research: Solid Earth, 96(B9), pp.14347-14375.
Frey, F.A. et al., 1990. Evolution of Mauna Kea Volcano, Hawaii: Petrologic and geochemical constraints on postshield volcanism. Journal of Geophysical Research: Solid Earth, 95(B2), pp.1271-1300.
Mauna Kea Volcano Eruptions
~4500 years ago (most recent)