Scientists consider raising Mauna Loa alert level

HILO — The Hawaiian Volcano Observatory hasn’t yet increased the alert level for Mauna Loa as it shows signs of increased activity.

But it is something that’s being considered.

“We’re talking about it internally,” said Tina Neal, HVO scientist-in-charge.

Mauna Loa was at an “advisory” level from September 2015 to June 2018 due to increased seismic activity.

Since then, it has remained at “normal,” which suggests a background state.

However, geologists have noticed a slight uptick in seismicity since August.

Neal said deciding when to change the alert level is a “bit of an art form.”

“One problem is we don’t want to jump around with these alert levels every day,” she said. “We saw some of what we are seeing now during the advisory period we came out of last year.”

Neal added those rates are still below the peak of activity during that period.

“It took us many months to go up to ‘advisory’ the last time,” she said.

On May 3, HVO said a “slight increase in the number of detected earthquakes at Mauna Loa was noted over the past month. Small earthquakes, mostly less than (magnitude 2.0), continued in long-active areas including beneath the northwest flank, summit region, and east flank.”

Slow inflation of the summit magma reservoir was detected with GPS instruments. But gas and temperature data showed no significant changes over the previous month.

“HVO continues to monitor the volcano closely and will issue another update in one month, or earlier should conditions change significantly,” the report said.

There are no signs of an imminent eruption.

Kilauea also remains at “normal” following last year’s massive eruption on its lower East Rift Zone.

Since early March, HVO has detected modest inflationary tilt at the Kilauea summit. One GPS station in the caldera collapse area recorded about 3 inches of uplift.

There also are signs of refilling of the deep magmatic reservoir between Puu Oo and Highway 130, which has been observed since the end of the 2018 eruption.

Email Tom Callis at tcallis@hawaiitribune-herald.com.