Monitoring Mauna Loa

Mar 8, 2017

Mauna Loa from Mauna Kea
Credit skyseeker / Flickr

Hawai'i Island’s Kīlauea Volcano gets a lot of attention with its two spectacular eruption locations. But the island’s dominant active volcano is also under close observation from scientists. We get details from HPR contributing reporter Sherry Bracken.

The United States Geological Survey’s Hawaiian Volcano Observatory Scientist in Charge, Tina Neal, is very clear that Mauna Loa poses no immediate threat to residents of  Hawai'i Island.

Tina: “ Mauna Loa is restless but there is no imminent eruption.”

Mauna Loa’s summit is inside Hawai'i Volcanoes National park, and  makes up a good part of Hawai'i Island.

Tina:  "Mauna Loa is the largest volcano on the planet. It covers more than half the surface of the Big Island. Mauna Loa last erupted in 1984.  The fact it’s been a good long time and we’ve been seeing elevated signs of unrest bring us to where we are today. “

While Kīlauea Volcano’s recent eruptions have been fairly slow moving and predictable, Mauna Loa is a different kind of volcano. Scientists have documented 33 eruptions since 1843.  In 1950, lava reached the then low population South Kona coast within 3 hours of the start of the eruption. Other eruptions have taken from 4 hours to a full day to reach the coast.

Tina:  “Typically Mauna Loa eruptions will produce quite a bit more lava, up to 100 times more lava per hour per day than Kīlauea.  They can be voluminous and very fast moving.  The impacts can be quite far reaching.  If Highway 11 were to be cut that would impact the entire island.  We would also anticipate a large and far ranging cloud of volcanic gas if we have a Mauna Loa eruption.”

Neal says scientists use a variety of tools to monitor volcanoes: a network of 60 seismometers around Hawai'i Island, tiltmeters and gas emission monitors, infrasound, and data from NOAA and NASA satellites.

Tina: “We’re continuing to see elevated earthquake activity and deformation activity. Before the volcano erupts we will expect to see many more earthquakes. In a week we’re seeing 20-ish earthquakes.  Before the ‘74 and ‘84 eruptions those numbers went way up, more than 100 a day. The other critical things we’d see is seismic tremor.  Magma starts moving, shaking the ground continuously. That would be a strong red flag.  We might see a sudden tilt change, indicating the ground is moving rather rapidly.”

Neal says her scientists are working closely with Hawai'i County Civil Defense and Hawai'i Volcanoes National Park to prepare for an eventual eruption. You can find more information about all of Hawai‘i’s volcanoes—including daily updates on Kīlauea and Mauna Loa at hvo.wr.usgs.gov.