Kīlauea alert level raised as magma intrusion in middle East Rift Zone continues

The Volcano Alert Level for ground-based hazards from the Big Island’s Kīlauea volcano was raised from advisory to watch as an intrustion of magma that began Sept. 14 in the middle East Rift Zone continues, increasing the possibilty of an eruption in that area.

The volcano’s Aviation Color Code also was raised from Yellow to Orange.

“Current activity is taking place in a remote area of Kīlauea’s middle East Rift Zone, within Hawaiʻi Volcanoes National Park,” said a volcanic activity notice issued at 12:33 a.m. today by the Hawaiian Volcano Observatory. “No changes have been detected in the lower East Rift Zone or Southwest Rift Zone.”

Intense and localized earthquakes between Maunaulu and Makaopuhi Crater, accompanied by ground deformation patterns indicating the growth of an underground crack growth began about 6 p.m. Sept. 14 following increased seismic activity that started about 2 hours earlier between Pauahi and Makaopuhi craters.

That included a magnitude-4.3 earthquake at 4:25 p.m. Saturday.

The dramatic increase in earthquake activity, which saw more than 280 temblors in 24 hours, coupled with ground deformation patterns uprift of Puʻuʻōʻō heralded the intrusion event that led to the increase in the volcano’s alert level.

The seismic activity has since decreased, but pulses of up to 25 earthquakes per hour and ground deformation continued as of the morning of Sept. 15.

Starting about 9 p.m. and continuing until 10 p.m. last night, infrasound instruments detected a strong signal typical of gas or steam venting and seismometers in the middle East Rift Zone are recording weak, sustained low frequency tremor.

The Hawaiian Volcano Observatory reported at 9:22 a.m. today that more than 340 shallow earthquakes were detected in the vicinity of the intrusion during the past day, most within 0.6 to 3.1 miles below the surface.

The Puʻuʻōʻō cone tiltmeter showed about 4 microradians of steady inflationary tilt throughout the past day, with no significant changes in rate or direction.

Those observations combined show that magma continues to move beneath the ground from summit storage chambers to the area between Maunaulu and Makaopuhi Crater.

The Hawaiian Volcano Observatory’s webcam network has not shown any evidence of eruptive activity and satellite data do not show any thermal anomalies at this time. Strong rainfall in the area also complicated interpretation earlier this morning.

An intrusion in 2007 in the same area erupted a very small pad of lava about the size of half a football field, so it is possible a similarly small eruption could take place without detection in these conditions.

Numerous eruptions took place in this area during the 1960s through the 1970s, most of which lasted less than a day to about 2 weeks.

Long-lived eruptions took place at Maunaulu from 1969-71 and 1972-74 and Puʻuʻōʻō from 1983-2018.

The location of any future outbreak will determine what areas could be in the path of new lava flows.

Rates of seismicity and ground deformation beneath the lower East Rift Zone and Southwest Rift Zone remain low. Current activity is restricted to the upper-to-middle East Rift Zone region of Kīlauea.

The Hawaiian Volcano Observatory is in close contact with Hawai‘i Volcanoes National Park and Hawai‘i County Civil Defense and will continue to monitor the activity closely to adjust the alert level and aviation color code for Kīlauea accordingly.

Should volcanic activity change significantly, a new volcanic activity notice will be issued.

Some hazards are present on the volcano already. Click here for more information.

Visit the Hawaiʻi Volcanoes National Park website for visitor information. 

For more information about the meaning of volcano alert levels and aviation color codes, click here.

The heightened activity beneath Kīlauea’s broader summit region during the past couple of days included a magnitude-4.3 earthquake at 4:25 p.m. Sept. 14.

The Uēkahuna tiltmeter at the summit began recording significant deflation about 7 p.m. Sept. 14, about an hour after the seismic swarm began in the middle East Rift Zone, and by the morning of Sept. 15 had recorded about 7 microradians of deflation related to the middle East Rift zone event.