The Big Island of Hawaii continues to shake and rattle, with USGS reporting 218 earthquakes centered on or near Hawaii Island over the last 7 days. 33 of those 218 have struck within the last 24 hours, with the latest being a minor quake to strike north of Hilo at 12:12 pm local time (6:12 pm ET.) Hawaii Island is the largest of the state island chain and is also the most volcanically active; the island is home to the active Hualalai, Mauna Loa, and Kilauea Volcanoes. No volcano is erupting on the island, but the seismicity may be an indicator that could change soon. (SEE ALSO: USGS Monitoring Volcanoes in California & Nevada for Earthquakes & Possible Eruptions)
In an update released this morning, the Hawaii Volcano Observatory (HVO) unit of the USGS wrote, “Kilauea volcano is not erupting, and no active lava has been observed since March 7, 2023. Summit seismicity remains elevated. Deformation has shifted to gradual deflation. No significant changes have been observed along either of the volcano’s rift zones over the past day.”
Overall, according to HVO, inflation at the summit of Kilauea is still higher than conditions preceding the January 5, 2023 summit eruption, although the rate of inflation decreased over the weekend with minor localized deflation. In addition to earthquakes happening around the island, a small flurry of earthquakes continue irregularly beneath Halemaʻumaʻu, Keanakākoʻi Crater, and the southern margin of Kaluapele (Kilauea caldera) since April 16. Overall, rates of summit earthquakes remain elevated, and additional earthquake flurries are possible. The most recent sulfur dioxide (SO2) emission rate of approximately 135 tonnes per day was measured on May 3.
In addition to summit eruptions, lava has been known to break out along eastern and western rift zones of the volcano. According to HVO, there has been no unusual activity along the rift zones although steady rates of ground deformation and seismicity continue along both. Measurements from continuous gas monitoring stations in the middle East Rift Zone—the site of 1983–2018 eruptive activity—remain below detection limits for SO2.
In the U.S., the USGS and volcano observatory units are responsible for issuing Aviation Codes and Volcanic Activity Alert Levels. Aviation Codes are green, yellow, orange, or red. When ground-based instrumentation is insufficient to establish that a volcano is at a typical background level of activity, it is simply “unassigned.” While green means typical activity associated with a non-eruptive state, yellow means a volcano is exhibiting signs of elevated unrest above known background levels. When a volcano exhibits heightened or escalating unrest with the increased potential of eruption, it jumps to orange. Finally, when an eruption is imminent with significant emission of volcanic ash expected in the atmosphere or an eruption is underway with significant emission of volcanic ash into the atmosphere, the code becomes red. Volcanic Activity Alert levels are normal, advisory, watch, or warning. As with aviation codes, if data is insufficient, it is simply labeled as “unassigned.” When the volcano is at typical background activity in a non-eruptive state, it is considered normal. If the volcano exhibits signs of elevated unrest above background level, an advisory is issued. If a volcano exhibits heightened or escalating unrest, a watch is issued while a warning is issued when a hazardous eruption is imminent.
For now, USGS has Kilauea at a Alert Level of ADVISORY and an Aviation Color Code of YELLOW.
While Kilauea isn’t erupting now, the volcano is constantly monitored by HVO and HVO/USGS continue to send out daily bulletins on its activity. Scientists continue to monitor if the recent earthquake activity will lead to something more substantial at Kilauea. “It is possible that an intrusion of magma beneath the surface or eruption of lava on the surface may occur with little or no warning. Additional messages will be issued as merited by volcanic activity,” warned the Hawaii Volcanoes National Park in April. The summit of Kilauea is contained entirely within National Park territory.