USGS HVO Press Release — Mauna Loa: How Well Do You Know the Volcano in Your Backyard?

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HAWAI‘I ISLAND, Hawai‘i — Mauna Loa's past eruptions and current status is the topic of a free presentation at Pu‘uhōnua o Hōnaunau National Historical Park on Wednesday, January 19, at 6:00 p.m.

Frank Trusdell, a U.S. Geological Survey Hawaiian Volcano Observatory geologist, has studied the volcano for nearly two decades and will be giving the talk about the largest volcano on Earth.

Mauna Loa has erupted 33 times since 1843. Its most recent eruption began on March 25, 1984. During that 23-day-long eruption, Mauna Loa sent lava flows to within 4 miles of Hilo city limits.

"Mauna Loa will erupt again, and there's a good chance that it will be during your lifetime," says Trusdell.

Earlier eruptions on the volcano have had an impact on West Hawai‘i. In 1950, lava flows from Mauna Loa's southwest rift zone crossed Highway 11 in three places on the Mamalahoa highway. The first flow, erupted from a fissure at an elevation of almost 10,000 feet, flowed from the vent to the ocean in less than three hours.

During Mauna Loa's 1859 eruption, lava flows traveled from vents high on the northwest flank of the volcano and entered the ocean near Kīholo Bay, a distance of over 50 km (31 miles), in eight days.

Mauna Loa has now slumbered for more than 26 years. Because of this long period of quiet, new residents may not be aware that Mauna Loa is an active volcano, and long-time residents may have forgotten the full potential of earthquake, volcano, and gas hazards posed by the volcano.

This talk is one of many programs offered by HVO in January, Hawai‘i Island's second annual Volcano Awareness Month. For more information about this presentation and other Volcano Awareness Month events, visit the HVO Web site at or call (808) 967-8844.

Daily updates about ongoing eruptions, recent images and videos of summit and East Rift Zone volcanic activity, maps, and data about recent earthquakes in Hawaii are posted on the HVO website at

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