Hawaii's Kilauea volcano, which began erupting on Dec. 20, has seen gradually increasing seismic activity in recent weeks, though the United States Geological Survey (USGS) indicates that no eruption activity has been observed since May 23.
The volcano's alert level remains at "advisory," and the aviation color code for the volcano is still at yellow. According to the USGS website, an advisory level is the state between the "watch" alert and "normal" alert levels. Following a change from a higher level of alert, an advisory alert indicates that the volcano is still being closely monitored for the possibility of renewed volcanic activity.
"The USGS Hawaiian Volcano Observatory lowered the Volcano Alert Level for ground-based hazards from "watch" to "advisory" and the Aviation Color Code from orange to yellow," according to its website.
The yellow aviation color code indicates a similar level of alert, only for aircraft operators.
"The lava lake filled 229 meters (752 feet) of the crater, to an elevation of 747 meters (2450 feet) asl, from the beginning of the eruption on Dec. 20, 2020, through May 13, 2021," according to the USGS's Recent Eruption page.
Kilauea is one of two volcanoes on the Big Island, noted by Go Hawaii as two of the most active volcanoes in the world. The other is Mauna Loa, which has not erupted since 1984. Previously, Kilauea was actively erupting from 1983 through 2018.
The USGS website states that the sulfur dioxide emissions at the volcano are still approximately double the previous period of non-eruption between 2018 and December 2020, with 60 metric tons per day being measured. In comparison, mid-eruption measurements in February and April recorded 800 metric tons per day.
There is still other measurable activity at the summit, with ongoing inflation and deflation, as well as continued gradual inflation, according to the USGS. The inflation center is indicated by measurements that have shifted to the southern portion of the caldera. A caldera is a volcanic crater that has a diameter many times that of the vent and is formed by the collapse of the central part of a volcano or by explosions of extraordinary violence.
While the lava lake has completely crusted over at this time, the USGS states that seismic activity has been gradually increasing in recent weeks. But that activity has yet to reach the levels observed prior to the Dec. 20 eruption.