Activity up slightly with increase in quakes under Kīlauea caldera, upper East Rift Zone

Kīlauea has been relatively quiet since the end of April when it seemed as though Hawaiian volcano goddess Pele might awake. Unrest has continued beneath Halemaʻumaʻu, the south caldera and the upper East Rift Zone, albeit at a much lower level.

Activity has again ticked up slightly during the past few days, with a flurry of earthquakes Thursday night under the south caldera region and an increase in quakes under the upper East Rift Zone beginning Friday night.

Earthquake counts remained above background levels as of Saturday morning.

During the past day, quakes mostly below magnitude-2 have clustered below the summit and upper East Rift Zone at depths between an average of 0.6 to 1.9 miles beneath the surface.

Ground deformation also continues beneath Halemaʻumaʻu and the south caldera region.

The Uēkahuna tiltmeter northwest of the summit showed overall flat tilt throughout the past day. At the same time, the Sand Hill tiltmeter southwest of the summit showed northwest inflationary tilt in the south caldera region.

Sulfur dioxide gas emission rates remain low.

Elevated seismic activity in the upper East Rift Zone is scattered. Seismicity in the Southwest Rift Zone is relatively low outside the summit region.

It’s not possible to say whether the most recent increase in the volcano’s activity will lead to an intrusion or eruption in the near future, or simply continue as seismic unrest at depth.

Changes in the character and location of unrest can occur quickly, as can the potential for an eruption.

Magma has been pressurizing the system beneath Halemaʻumaʻu and Kīlauea’s south caldera region for several weeks, activating seismicity in the upper East Rift Zone. There also has been inflation in the caldera south of Halemaʻumaʻu.

A period of heightened unrest began April 27, lasting until earlier this month.

Earthquake counts were still as many as 280 in a 24-hour period as of May 3. Those quakes were focused primarily in an area from the southeast side of Kaluapele, Kīlauea’s caldera, beneath Keanakākoʻi crater extending to the intersection with Hilina Pali Road.

Quakes peaked at an average of 360 per day by the end of April, with more than 1,500 recorded beneath the upper East Rift Zone and southern end of the caldera throughout a 5-day period from April 27 to May 1.

Activity slowed significantly by May 4, with earthquake counts falling to just 8 that morning. Ground deformation also effectively ceased beneath Halemaʻumaʻu and the south side of Kalaupele and Keanakākoʻi crater.

The period of heightened unrest was finished by May 5, with activity similar to before the spike.

It didn’t take long for earthquake counts to increase again, however, with the number of quakes back up to as many as 250 in a 24-hour period by May 8.

That uptick lasted for about 3 to 4 days. By May 11, seismicity returned to slightly above background levels and remained that way until Thursday night.

Ground deformation has continued since May 6 beneath Halemaʻumaʻu and the south side of Kalaupele and Keanakākoʻi crater after a brief stop related to a deflation-inflation event beneath Halemaʻumaʻu.

The volcano’s alert level remains at Advisory and the current aviation color code is yellow.

The Hawaiian Volcano Observatory continues to provide daily updates about activity at Kīlauea and is closely monitoring the volcano for signs of increasing activity.

Should volcanic activity change significantly, a Volcanic Activity Notice will be issued.

You can find the daily activity updates here. The Kīlauea activity summary is also available by phone at 808-967-8862.