The world’s largest active volcano continues to rumble

HONOLULU (THE HON) — Mauna Loa remains in a yellow advisory with dozens of small earthquakes per day, suggesting the large volcano may be headed for eruption.

The unrest began back in July and peaked in September with 40-50 small earthquakes per day. Lately there have been 10 to 20 of them.

Although an eruption is imminent, officials say there are other signs of unrest.

“We continue to see the same level of inflation at the summit, indicating magma movement into this shallow reservoir on Mauna Loa,” said Hawaiian Volcano Observatory geophysicist Andrea Ellis.

Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island of the Hawaiian archipelago. It’s not the tallest (that title goes to Mauna Kea), but it’s the largest and makes up about half of the island’s landmass.

The last eruption of Mauna Loa was 38 years ago. It has erupted 33 times in written history since 1843. Its height gives it steeper slopes that allow lava to flow quickly down the slopes.

Hawaii County Civil Defense is having a difficult time coordinating what will lead to the eruption. Every eruption since 1843 has started at the summit. Half the time the volcano would also start erupting from vents at lower elevations. The other half of the time it erupted only in the caldera at the top.

Hawaiian volcanoes like Mauna Loa tend not to have explosive eruptions like Mount St. Helens, for example. Still, lava covering one of the island’s many two-lane highways will be difficult for residents and first responders.

“Closing major arteries will disrupt life,” said Hawaii County Civil Defense Administrator Talmadge Magno. “I went down to lower Pune a couple of weeks ago and there are still no roads. They are planned to be reconstructed, but life is returning. So live on an active volcano. They are dynamic and we have to face it.”

At the same time, residents must have a plan.

“We have to be ready for this volcano when it erupts and affects society. But what about the previous stuff? What about earthquakes?’ asked Big Island resident Marnie Renner. “If an earthquake happens, are people ready for it? Simple things like gas in your car, propane tanks, having an emergency kit or backpack for every member of your family.”

There may also be situations where families are separated.

“They have to be aware of the situation they’re living in, where they’re working with their families to do their jobs, especially when they’re doing their daily chores and they’re separated. They have to know how to communicate to the point where, you know, they’ll even have a family plan, maybe a place to rally,” Magno said.

During an eruption, civil defense can rely on HVO maps to pinpoint where the flows will go, to keep people out of harm’s way and to avoid evacuating random large communities if not necessary.

The Hawaiian Volcano Observatory has more than 60 GPS stations on Mauna Loa that take measurements to estimate the location and amount of magma accumulating beneath the surface.

Scientists use inclinometers to track long-term changes in the earth’s slope, helping them determine when the land is swelling or sinking. A rapid change in slope can indicate when an eruption will occur.

There is also a thermal web camera on top of Mauna Loa that detects the presence of heat. And satellite radar can track the swelling and deflation of the earth.

The Associated Press contributed to this report.