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Rising gradually to more than 4 km (13,100 ft) above sea level, Mauna Loa is the largest active volcano on our planet.


Summary

Its long submarine flanks descend to the sea floor an additional 5 km (16,400 ft), and the sea floor in turn is depressed by Mauna Loa's great mass another 8 km (26,200 ft). This makes the volcano's summit about 17 km (55,700 ft) above its base! The enormous volcano covers half of the Island of Hawai‘i and by itself amounts to about 85 percent of the area of all the other Hawaiian Islands combined.

The Hawaiian name "Mauna Loa" means "Long Mountain." This name is apt, for the subaerial part of Mauna Loa extends for about 120 km (74 mi) from the southern tip of the island to the summit caldera and then east-northeast to the coastline near Hilo.

Mauna Loa is among Earth's most active volcanoes, having erupted 33 times since its first well-documented historical eruption in 1843. It has produced large, voluminous flows of basalt that have reached the ocean eight times since 1868. It last erupted in 1984, when a lava flow came within 7.2 km (4.5 mi) of Hilo, the largest population center on the island. Mauna Loa is certain to erupt again, and with such a propensity to produce large flows, we carefully monitor the volcano for signs of unrest.

Read our Frequently Asked Questions about Mauna Loa.

News

Date published: June 17, 2021

USGS HVO Information Statement — Magnitude-4.5 earthquake northeast of Pāhala, Island of Hawai‘i

The U.S. Geological Survey's Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.5 earthquake located beneath the south part of the Island of Hawai‘i, in the district of Kaʻū, on Thursday, June 17, at 4:32 p.m., HST.

Date published: June 10, 2021

Volcano Watch — Campaign season is here! Another way HVO tracks changes on Hawaiian volcanoes

Geodetic surveys measure the change in shape of our volcanoes due to changes in magma supply and storage. The USGS Hawaiian Volcano Observatory (HVO) has a long history of using many different types of instruments and technologies over the decades to detect these changes.   

Date published: June 8, 2021

New HVO webcam: [MKcam] Mauna Loa's Summit and Northeast Rift Zone from Mauna Kea

A new USGS Hawaiian Volcano Observatory webcam provides views of Mauna Loa’s summit and Northeast Rift Zone. The webcam view is to the south from its position on the slope of Mauna Kea. Near-live webcam views and a 24-hour animated GIF are available here: https://www.usgs.gov/volcanoes/...

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