BIG ISLAND (HawaiiNewsNow) - The amount of small earthquakes beneath the summit of Mauna Loa has more than tripled recently prompting the U.S. Geological Survey to increase the volcano alert level from "normal" to "advisory". On the color scale, it went from green to yellow.
"Over the past year we've been locating, on average, around 150 earthquakes per month," says Weston Thelen with the U.S.G.S. who says normally, fewer than 40 earthquakes a month are reported.
The last time Mauna Loa erupted, was in 1984. The lava flowed for 22 days. More than 30 years later, the mountain is stirring again.
"Really, we're seeing a persistence in this unrest," says Thelen, "We're not saying that an eruption is imminent, we're not even really certain that there is going to be an eruption." But the shallow earthquakes are occurring in the same areas that preceded the mountain's most recent eruptions.
Should the unrest continue to increase, the agency could up the level to Orange and then Red which would mobilize crews at the county, state and federal levels.
But scientists aren't urging any action yet but simply want people to be aware of the growing movement under the mountain.
"It's possible that the increased level of activity at Mauna Loa could continue for many months, or years, without leading to an eruption," said Tina Neal, HVO's Scientist-in-Charge. "It is also possible that the current unrest could be a precursor to the next eruption of Mauna Loa. But at this early stage, we cannot determine precisely which possibility is more likely."
Mauna Loa has been rumbling for awhile and scientists say it's not a matter of if, but when.
"I can be certain in saying that Mauna Loa will erupt again. It is not dormant, there is magma that is accumulating," says Thelen.