"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.
Comment: See also: Volcanic eruptions and earthquakes increasing across the planet