Update: Seismic swarm that produced more than 350 earthquakes during past two days in area near Kīlauea summit ends

Updated at 10:07 a.m. Dec. 31: Kīlauea volcano is not erupting. The seismic swarm that began Dec. 29 south of Halemaʻumaʻu crater ended Dec. 30, coincident with a drop in inflation recorded at Sand Hill.

The Hawaiian Volcano Observatory says that during the past day, moderate rates of seismicity have returned to the volcano’s southern summit region, extending from the area south of Halemaʻumau and southwest to the Koʻae fault zone. Seismic activity is moderate in the upper East Rift Zone, but remains low along the Southwest Rift Zone.

At about 11 a.m. Saturday, the rate of inflation at the Sand Hill tiltmeter, located just south of the Kīlauea caldera, decreased significantly and continues to record slight inflation. The summit tiltmeter at Uēkahuna has recorded deflationary tilt during the past day, possibly starting a new deflation-inflation event.

The strong swarm of more than 350 earthquakes and rapid inflation during the past couple of days south of the caldera indicated magma was being emplaced at relatively shallow levels. This particular event led to an intrusion, but it is possible that similar events might lead to an eruption in the future.

There are currently no signs of an imminent eruption at Kīlauea, but the volcano’s summit region remains unsettled, with a high level of inflation and continued seismic activity.

Unrest could continue to wax and wane with fluctuating input of magma to the area and eruptive activity could occur in the near future with little or no warning.

No unusual activity has been noted along the middle and lower sections of Kīlauea’s East Rift Zone.

Original post: Kīlauea volcano on the Big Island is not erupting; however, elevated unrest and increased seismicity to the south of the summit started shortly after 1 p.m. Friday.

The seismicity followed a sharp increase in inflation recorded by the Sand Hill tiltmeter that began at 12:30 p.m. Friday, which continues today. The summit tiltmeter at Uēkahuna began recording slight deflationary tilt at about the same time.

There were more than 80 locatable earthquakes in the region throughout the following 6-hour period and many smaller earthquakes.

Earthquake swarms like this can precede eruptions, but the Hawaiian Volcano Observatory said there was no lateral or upward migration of earthquakes that would suggest magma is moving toward the surface.

There are currently no signs of an imminent eruption. Seismicity has not reached the levels that immediately preceded recent Kīlauea summit eruptions.

The increased seismicity began just to the south of Halemaʻumaʻu crater and has progressively included a larger region to the south of the caldera about 1 to 2.5 miles south of Halema‘uma‘u. The seismicity was occurring at depths of 0.5 to 2 miles, with magnitudes ranging from a maximum of 2.5 to less than 1.

Since the increase in seismicity started yesterday, roughly 350 earthquakes, most less than magnitude-2.5, have happened at depths of 0.5 to 2 miles. The area of the unrest has progressively widened to the southwest toward the Koʻae fault zone.

The current rate of earthquakes is slightly higher than what was seen in October during the unrest that accompanied the magma intrusion in the same area.

Earthquakes are continuing today in the region, with slight variations in rate and size.

Kīlauea’s summit region also remains at a high level of inflation. Relative tilt is above the level reached prior to the most recent eruption in September and is higher than at any time since the 2018 lower East Rift Zone eruption.

Periods of increased or decreased numbers of shallow earthquakes can be expected to continue during repressurization of the summit magma reservoir, which has been ongoing since the end of the September eruption.

It is uncertain if this increased activity will lead to an eruption or another major intrusion of magma in this area; however, eruptive activity is possible with little or no warning.

The onsets of previous summit eruptions have been marked by strong swarms of earthquakes caused by magma moving toward the surface 1 to 2 hours before the appearance of lava. This type of earthquake activity is not being detected at this time.

No unusual activity has been noted along Kīlauea’s East or Southwest rift zones.

The current Volcano Alert Level remains at advisory.

The last eruption at Kīlauea summit ended Sept. 16 and was followed by a significant intrusion to the southwest of Kīlauea caldera. Seismicity has waxed and waned since, alternating between the southwest area, the south end of the caldera and the upper East Rift Zone.

Most recent seismicity has alternated between the summit caldera and the upper East Rift Zone.

A map of intrusive activity that happened in October is available here. A map summarizing the recent unrest around Kilauea’s summit, from Nov. 11 to Dec. 12, can be found here.

Hawaiian Volcano Observatory continues to closely monitor Kīlauea volcano, watching for any signs of accelerated rates of earthquakes or ground deformation, or signs of shallowing earthquake locations, which usually precede a new lava outbreak or propagating dike.

Scientists are also closely monitoring gas emissions and webcam imagery.

Check out Kīlauea live stream here and MITDcam, which watches the volcano’s Southwest Rift Zone.

You can also check out the most recent “Volcano Watch” article about the most recent eruption in the volcano’s Southwest Rift Zone that happened on New Year’s Eve in 1974.