HILO, Hawaii (KHON2) — Scientists have raised the alert level for Mauna Loa from normal to advisory.

This increase in alert level does not mean that an eruption is imminent nor that progression to an eruption is certain. A similar increase in activity occurred between 2014 and 2018 and no eruption occurred.

“In terms of earthquakes before this current change we had on average about 20 events per week. And now we’re closer to the 50 and sometimes we range as high as 100 per week,” according to Frank Trusdell, a research geologist at the Hawaii Volcano Observatory.

Trusdell explained that they’re also seeing an expansion or deformation under the volcano, which means lava is likely filling in the area.

“Even though the volcano is showing some signs of reawakening, an eruption is not imminent,” Trusdell said.

UH Geology Professor Scott Rowland said alerts do go up and down.

“For example, Mauna Loa was at advisory level in 2014 to just a year ago when Mauna Loa became very quiet. It happened to be during the eruption crisis of Kilauea a year ago,” Rowland said.

Rowland explained that active volcanoes will have periods of quiet, then activity, then quiet. But he warned that Mauna Loa will eventually erupt again.

Trusdell said an eruption would follow a considerable jump in the number of earthquakes, along with an increase in the expansion at the summit.

“If we look at the two prior examples, I always refer to 1975 and 1984 because those were the periods of time in which we had modern instruments continuously recording and sending information back to the observatory.”

Trusdell explained that prior to the 1975 and 1984 eruptions, they were logging several hundreds of earthquakes per day, compared to the roughly 50 to 100 earthquakes we are currently seeing each week.

He also noted that the ground deformation rates across the summit in 1975 and 1984 increased at a more rapid rate.

Shallow earthquakes are occurring in locations similar to those that preceded Mauna Loa’s most recent eruptions in 1975 and 1984, but they have not reached the quantity, level of intensity, or the consistency.

The recent activity and observations indicate the volcano is no longer at a background level of activity. Accordingly, HVO is elevating the Mauna Loa alert level to ADVISORY and the aviation color code to YELLOW.

Alert levels and aviation color codes are explained here: https://volcanoes.usgs.gov/vhp/about_alerts.html

Scientists say it is possible that current low-level unrest will continue and vary in intensity for many months, or even years without an eruption. It is also possible that the current unrest is an early precursor to an eventual eruption. At this time, we cannot determine which of these possibilities is more likely. HVO expects that days or weeks prior to an eruption, monitoring instruments will detect signs of an increased potential for eruption. These signs could include further increases in rates of earthquakes and ground deformation, increases in the sizes of earthquakes, an increase in surface temperatures, or an increase in visible steam plumes or sulfur dioxide emissions.

However, it is also possible that the timeframe to eruption could be shorter – hours to days. All communities on the flanks of the volcano should be prepared. HVO continues to monitor the volcano closely and will report any significant changes. HVO is in close touch with Hawaii County Civil Defense and other agencies responsible for public safety.

“It’s just a reminder that Mauna Loa is an active volcano and it will have these periods of acting, quiet, active, quiet, but almost certainly, Mauna Loa will erupt some day. Exactly when is hard to say,” Rowland said.

Stay informed about Mauna Loa by following volcano updates and tracking current monitoring data on the HVO web page http://hvo.wr.usgs.gov/activity/maunaloastatus.php or by signing up to receive updates by email at this site: http://volcanoes.usgs.gov/vns/

Hawaii County Civil Defense Agency is in constant communications with HVO. If anything develops that may affect your safety, you will be informed. Please sign up for Civil Defense notifications by visiting Hawaii County Civil Defense Agency webpage at http://www.hawaiicounty.gov/civil-defense/.