Skip to main content
U.S. flag

An official website of the United States government

Mauna Loa

Find U.S. Volcano
Current Alerts
Mauna Loa
green NORMAL, 2024-10-03 19:05:08 UTC

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

Quick Facts

Location: Island of Hawai‘i

Latitude: 19.475° N

Longitude: 155.608° W

Elevation: 4,169 (m) 13,679 (f)

Volcano type: Shield

Composition: Basalt

Most recent eruption: Began Nov. 27, 2022

Nearby towns: Hilo, Waikōloa, Ocean View, Captain Cook, Miloli‘i, Nā‘ālehu, Pāhala

Threat Potential: Very High*

*based on the National Volcano Early Warning System

Summary

Its long submarine flanks descend to the seafloor an additional 5 km (16,400 ft), and the seafloor 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 34 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. During the 1984 eruption, a lava flow came within 7.2 km (4.5 mi) of Hilo, the largest population center on the island. During the most recent eruption, in 2022, lava flows came to within 1.7 miles (2.8 kilometers) of the Daniel K. Inouye Highway (Saddle Road). 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.

See the geonarrative, Mauna Loa: Preparing for the next eruption of Earth's largest active volcano.

News

Volcano Watch — Webcam upgrades keep a sharp eye on Hawaiian volcanoes

Volcano Watch — Webcam upgrades keep a sharp eye on Hawaiian volcanoes

New USGS Data Release — Mauna Loa 2022 eruption geospatial data

New USGS Data Release — Mauna Loa 2022 eruption geospatial data

Volcano Watch — Introducing the Island of Hawaiʻi Interagency Operations Plan for Volcanic Eruptions

Volcano Watch — Introducing the Island of Hawaiʻi Interagency Operations Plan for Volcanic Eruptions

Publications

2018 update to the U.S. Geological Survey national volcanic threat assessment

When erupting, all volcanoes pose a degree of risk to people and infrastructure, however, the risks are not equivalent from one volcano to another because of differences in eruptive style and geographic location. Assessing the relative threats posed by U.S. volcanoes identifies which volcanoes warrant the greatest risk-mitigation efforts by the U.S. Geological Survey and its partners. This update

Authors
John W. Ewert, Angela K. Diefenbach, David W. Ramsey

Science

How are lava flows mapped in Hawaii?

Lava flow mapping provides situational awareness of volcanic eruptive hazards in Hawaii. During eruptions, USGS Hawaiian Volcano Observatory (HVO) scientists employ a variety of techniques to collect and disseminate map data depicting key eruptive features, especially lava flows.
link

How are lava flows mapped in Hawaii?

Lava flow mapping provides situational awareness of volcanic eruptive hazards in Hawaii. During eruptions, USGS Hawaiian Volcano Observatory (HVO) scientists employ a variety of techniques to collect and disseminate map data depicting key eruptive features, especially lava flows.
Learn More

1926 Eruption

Mauna Loa's recognized eruptive pattern is a summit eruption followed—within hours, days, or months—by a flank eruption. In 1926, there was a brief summit eruption, followed by 14 days of eruption on the Southwest Rift Zone.
link

1926 Eruption

Mauna Loa's recognized eruptive pattern is a summit eruption followed—within hours, days, or months—by a flank eruption. In 1926, there was a brief summit eruption, followed by 14 days of eruption on the Southwest Rift Zone.
Learn More

Monitoring Data for Mauna Loa

For more information on how electronic tiltmeters and GPS receivers help monitor the deformation of Kīlauea Volcano, see the HVO Deformation page.
link

Monitoring Data for Mauna Loa

For more information on how electronic tiltmeters and GPS receivers help monitor the deformation of Kīlauea Volcano, see the HVO Deformation page.
Learn More
Was this page helpful?