The Aloha State of Hawaii is shaking quite a bit lately; according to USGS, there have been 219 earthquakes there over the last 7 days, all of which have been on or around the Big Island of Hawaii. Hawaii Island is the largest of the 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.
The USGS has the Alert Level set to “Advisory” and the Color Code to “Yellow” at Kilauea Volcano, indicative of the seismic activity there.
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.
“Kīlauea volcano is not erupting, and no active lava has been observed since March 7, 2023,” reports the Hawaii Volcano Observatory of USGS in the May 1 observatory daily update. “Tiltmeters in the summit region are tracking no substantial changes at this time, but summit seismicity remains slightly elevated. No significant changes have been observed along either of the volcano’s rift zones over the past day.” Due to an increase in earthquake activity, USGS decided to post daily updates about the volcano starting on April 21.
Tiltmeters in the summit region have tracked no substantial changes since a period of deflationary tilt yesterday morning. Small flurries of earthquakes have occurred irregularly beneath Halemaʻumaʻu, Keanakākoʻi Crater, and the southern margin of Kaluapele (Kīlauea caldera) since April 16. Rates of summit earthquakes remain elevated, and continued earthquake flurries are possible. The most recent sulfur dioxide (SO2) emission rate of approximately 75 tonnes per day was measured on April 26.
According to USGS and their HVO unit, recent eruptions at the summit of Kīlauea volcano have been occurring within a closed area of Hawaiʻi Volcanoes National Park. High levels of volcanic gas are the primary hazard of concern, as this hazard can have far-reaching effects downwind. Large amounts of volcanic gas—primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)—are continuously released during eruptions of Kīlauea. As SO2 is released from the summit, it reacts in the atmosphere to create the visible haze known as vog or volcanic smog that has been observed downwind of the volcano. Vog creates the potential for airborne health hazards to residents and visitors, damages agricultural crops and other plants, and affects livestock.
While Kilauea could be coming to life, there is no concern at the other two active volcanoes on the island. Hualalai last erupted in 1801, destroying areas on the north side of modern day Kona and creating the land area that is now home to Kona Airport. Mauna Loa last erupted in November/December of last year; typically several years pass in between eruptions at that volcano, which is the world’s largest.
In the meantime, scientists continue to see 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.