Photo and Video Chronology - Kīlauea - February 4, 1998

Release Date:

In the aftermath of a surge

[This update current as of February 4, 1998. Eruption updates are posted approximately every two weeks. More frequent updates will accompany drastic changes in activity or increased threat to residential areas.]

Surge of magma from Kilauea's summit downrift to Puu Oo on January 14;Kilauea Volcano's east rift zone only now returning to a typical pattern of behavior.

On January 14 at 6:15 p.m., a surge of mama disturbed the upper crust beneath Kilauea caldera. Immediate effects, occurring in the subsequent 12 hours, included a swarm of earthquakes (mostly magnitude 1-2, largest 2.2) at the summit of Kilauea and discharge of lava from vents on the south side of Puu Oo, 17 km to the east. The earthquakes and surge disturbed the equilibrium of the eruption, an effect only now subsiding as the eruption returns to a pattern more typical of previous months. All these events are part of Episode 55, the eruptive episode that began February 24, 1997, and is continuing today. If you wish to learn more of the seismic, tilt, and eruptive events that occurred January 14-16, check the Jan. 17 archive.

In the three weeks since January 14th

• The summit of Kilauea Volcano has slightly inflated and deflated several times over periods of hours to days. In contrast, during previous months the summit typically showed only minor changes as the eruption proceeded in a more steady-state routine.
• Supply of lava to the tube system was interrupted at least twice, coincident with episodes of summit inflation and deflation.
• At the coast, the dwindling supply of lava to the tube system resulted in diminished discharge of lava to the ocean. Consequently, the steam plumes that commonly billow from the lava-water interface periodically weakened and vanished for a day or two at a time.
• Beginning at 5:39 p.m. on January 27 and persisting into January 28, a swarm of earthquakes struck the area beneath Namakani Paio campground, 2 km northwest of Kilauea Volcano's summit. Several of these earthquakes rattled houses in the area and were felt from Hilo to Ocean View Estates, sites 40-50 km from the epicenter. The largest earthquake of the sequence, magnitude 4.4, occurred shortly after 8:00 p.m. on January 27.

The Puu Oo vent area remained relatively unchanged in the weeks following the January 14 surge. Lava issued profusely from the crater and at vents on the south flank until about January 26. Intense fuming since that time indicates that magma is still degassing in the shallow subsurface, but it is visible only periodically in the vent orifices. Consequently, nighttime glow from the Puu Oo area is slight to absent. Lava has been visible in the tube system except when supply was interrupted briefly (Jan. 15-16; Jan. 19-20).

Summit tilt, depicted in the tiltmeter record shown above, may be likened to a slowly rolling carpet ride, although the amplitude of ground changes are inconsequential except to delicate instruments. The abrupt inflation-deflation episode on January 14 corresponds to the movement of a large slug of magma from the summit area to Puu Oo. Since that time, magma flux through the tube system has been relatively constant, about 600,000 cubic meters per day. This flux varied by about ten percent when measured over a 30-minute interval on January 22.

(If tilt and its discussion means nothing to you, but you'd like to learn more, then explore a well-illustrated Kilauea case history for further insight.)

The Namakani Paio earthquake swarm coincides roughly with the onset of a more stable pattern of tilt at the summit. Conceivably the earthquakes, which occurred the evening of January 27, brought crustal stress more closely to equilibrium.

The most obvious change visible to visitors at the National Park has been the numerous breakouts of lava along the coastal plain. In the days and weeks following the January 14 surge, fluctuating lava supply to the tube system periodically overwhelmed the tubes. On these occasions, lava upwelled, punched through weak zones in the tubes' roofs, and spread slowly outward on the ground surface. The coastal plain is highly subject to such breakouts because the tubes approach the plain by traversing down high, steep slopes. Elevation contrasts of nearly 500 m create substantial hydraulic head, adding additional force to lava when it fills the tubes.

Eruption-viewing opportunities change constantly, so those readers planning a visit to the volcano should contact Hawaii Volcanoes National Park for the most current eruption information (808-985-6000). Additional photographs and descriptions of east rift eruptive activity may be found on the University of Hawai`i's web site.

This map current as of February 3, 1998.