#earthquake swarm

On Sunday, Sept. 13, 8 a.m. HST, a magnitude-4.0 earthquake occurred 2 miles south of Pāhala on the Island of Hawaiʻi at a depth of 8 miles below sea level. The earthquake had no apparent impact on either Maunaloa or Kīlauea volcanoes, according to the Hawaiian Volcano Observatory.

The HVO reports that these tectonic events are not related to magma movement. “Stress gradually accumulates over time and is most likely due to the weight of the island,” according to the HVO.

A magnitude-4.2 earthquake reported at 11:37 p.m. on Monday, Jan. 26, occurred 1 mile northwest of Pāhala on the Island of Hawaiʻi at a depth of 21 miles below sea level. Scientists with the Hawaiian Volcano Observatory say the earthquake was part of the ongoing deep swarm beneath Pāhala that began about 7 years ago and is not directly related to volcanic activity.

Kīlauea summit region has been remarkably quiet, from an earthquake standpoint, since the current eruption began on the night of Dec. 23, 2024. Since the end of episode 40 on the evening of Jan. 12, however, nearly a dozen small earthquake swarms have occurred involving earthquakes 1–2.5 miles beneath Halemaʻumaʻu and the summit caldera of Kīlauea.

Ongoing swarms of earthquakes and persistent volcanic tremors indicate active magmatic movement, fueling anticipation about Kīlauea’s next eruption.

Most of the earthquakes are volcano-tectonic earthquakes that accompany crack opening due to magmatic pressure, according to the Hawaiian Volcano Observatory.

Kamaʻehuakanaloa volcano (formerly known as the Lōʻihi Seamount), offshore to the southeast of the Island of Hawaiʻi, entered a period of heightened seismic unrest around 2 a.m. HST on Monday, Jan. 21. Seismicity ceased by 8 a.m. HST and a continuation of earthquake swarm activity at this time seems unlikely, according to an update from the Hawaiian Volcano Observatory.

The HVO issued as status update saying there have been over 70 earthquakes so far in this swarm, with 32 events greater than magnitude 2 and two events greater than magnitude 4. The largest earthquake has been a magnitude-4.3 event that occurred Saturday at 12:05 p.m. HST, at a depth of 5.8 km (3.6 mi) below sea level and 4.8 km (3.0 mi) below the volcano’s summit.

Earthquake activity has increased in Kīlauea’s middle East Rift Zone, near Makaopuhi Crater. Ground deformation patterns west (uprift) of Puʻuʻōʻō suggest that another intrusive event could be occurring in this region, but scientists with the Hawaiʻi Volcano Observatory say Kīlauea is not erupting at this time.

In the late hours of Nov. 27, 2022, Mauna Loa began erupting. Lava was visible on the west side of the Island of Hawaiʻi, from Kailua-Kona to Waikoloa. Social media was ablaze with pictures and commentary of lava flows descending the west flank toward communities. 

Earthquake swarms like this can precede eruptions, but there is no lateral or upward migration of earthquakes that would suggest magma is moving toward the surface at this time.

Scientists with the Hawaiian Volcano Observatory issued an information statement on Monday saying there has been a 24 hour period of “elevated unrest” at Kīlauea.

A 3.8 magnitude earthquake reported just before midnight on Sunday May 7, 2023 in Pāhala on Hawaiʻi Island, was part of a swarm of earthquakes that has been occurring in the region since 2019. Scientist with the Hawaiian Volcano Observatory say these quakes may be related to deep transport of magma in the hotspot beneath the Island of Hawaiʻi, but pose no volcanic threat to residents. 

“Resumption of eruptive activity at Kīlauea summit no longer appears to be imminent, although it is possible that another intrusion or resumption may occur in the near future with little or no warning,” according to an update from the Hawaiian Volcano Observatory. 

A shallow earthquake swarm has been detected beneath the summit of Kīlauea Volcano, accompanied by significant surface tilt excursion, according to the Hawaiian Volcano Observatory. HVO scientists say resumption of eruptive activity at Kīlauea summit is likely imminent.

A swarm of small earthquakes beneath the Kīlauea caldera is being attributed to repressurization after the end of the last eruption. There were approximately 25 earthquakes of less than magnitude 2 that occurred between 6 and 9 p.m. HST on Friday, Dec. 30, 2022.

An estimated 38 small earthquakes have occurred beneath the summit of Mauna Loa volcano since 2 a.m. on Friday, Sept. 23, 2022. The US Geological Survey’s Hawaiian Volcano Observatory reports that the quakes are part of a small seismic swarm beneath the summit caldera region.

Data from seismometers installed in the Manuʻa Islands in American Samoa this week confirms that the ongoing earthquake activity is related to Taʻū Island volcano and not Ofu-Olosega.

“If activity escalates to an eruption, it will most likely include slow-moving lava flows or low-level explosions of lava that are localized to a small area. An eruption like Hunga Tonga–Hunga Ha’apai in Tonga earlier this year is extremely unlikely as it is a different type of volcano. Volcanoes in Tonga erupt much more explosively than ones in American Samoa and Hawaiʻi,” according to the Hawaiian Volcano Observatory.

Increased seismic activity beneath Kamaʻehuakanaloa “Lōʻihi” seamount is likely the result of magma movement beneath the surface, according to scientists with the Hawaiian Volcano Observatory.