. . . At the end of January the eruption rate slowed for a 24-hour interval; lava circulated sluggishly in the Pu`u `O`o lava pond, and views through skylights into lava tubes confirmed that the level of lava traveling through them was low. Later, on 8 February, the lava pond was 84 m below the N spillway rim, the same level seen last month, indicating that the rate of lava discharge had returned to normal. Surface flows were intermittently active above and at the base of Pulama pali during this interval, but above Paliuli views through skylights showed little change.

At the W Kamoamoa bench, lava continued to plunge into the ocean. In the first half of February the bench underwent two major collapses. Each dislodged a 200 x 30 m area that slid into the sea, but after each collapse new lava reconstructed the area lost. On 22 February, a substantial collapse took place, involving an area ~25 m wide extending along 400 m of coastline. Collapses also exposed active lava tubes. Their escaping lava built littoral cones along the coastal margin. The 22 February collapse deposited spatter fallout to 80 m inland, and in addition, fine rock fragments and "Limu o Pele" (thin flakes of basaltic glass) to 200 m inland.

An earthquake struck on 1 February with a preliminary magnitude of 5.2. It was received at all stations on the HVO network, and was felt over the entire island of Hawaii as well as parts of Maui, Molakai, Oahu, and Kauai; no damage was reported. The earthquake had an epicenter 18 km S of Kīlauea's summit, just offshore, and its focal depth was 33 km. After the earthquake, seismologists counted over 300 aftershocks, ~100 large enough to locate.

From mid-January through February the number of short-period microearthquakes was low beneath the summit, but above average along the east rift zone. The number of long-period microearthquakes on the east rift zone was moderate in the first half of February and slightly above average in the last half of February.

Tremor continued along Kīlauea's east rift zone. In the last half of January the tremor fluctuated over an amplitude range up to 3x background. During this time amplitude commonly remained consistent for 1-2 hours. This behavior created a "banded" seismic record, on which the bands represent multiple seismic traces of similar amplitude. The banded seismic records in the first half of February also recorded 1-2 hours of consistent tremor amplitude. During the last half of February banded tremor persisted for 2-3 hours, as consistent tremor with amplitudes 3-4x background, was followed by 2-3 hours of lower amplitude tremor.

Geological Summary. Kilauea overlaps the E flank of the massive Mauna Loa shield volcano in the island of Hawaii. Eruptions are prominent in Polynesian legends; written documentation since 1820 records frequent summit and flank lava flow eruptions interspersed with periods of long-term lava lake activity at Halemaumau crater in the summit caldera until 1924. The 3 x 5 km caldera was formed in several stages about 1,500 years ago and during the 18th century; eruptions have also originated from the lengthy East and Southwest rift zones, which extend to the ocean in both directions. About 90% of the surface of the basaltic shield volcano is formed of lava flows less than about 1,100 years old; 70% of the surface is younger than 600 years. The long-term eruption from the East rift zone between 1983 and 2018 produced lava flows covering more than 100 km2, destroyed hundreds of houses, and added new coastline.

Information Contacts: T. Mattox and P. Okubo, HVO.