September 12, 1997

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Lava Entering Sea

The billowing steam plumes rising from where lava enters the ocean are an indication that Kilauea's eruption may be returning to normal, after several months of unsettled behavior. From April through June of this year, the eruption was characterized by shifting vent locations on the west and south flanks of Pu`u `O`o. During this interval, lava flows extended less than 2.5 mi (4 km) from Pu`u `O`o, both because of the on-and-off activity at various vents and because the eruption was interrupted by ten pauses, ranging in duration from 3 to 15 hours.

The eruption began to settle into more consistent behavior in the summer. Since mid-June, there have been no pauses, and in the last month, only a single area on the flank, the "south shield" has produced lava flows. The eruption has resumed the pattern of activity that has been typical for much of the last 10 years: lava is traveling from the vent to the ocean encased within lava tubes. Since July 12, lava has entered the ocean near the eastern boundary of Hawai`i Volcanoes National Park. In mid-August, a new flow overran the ruins of the Waha`ula heiau. Lava is now entering the ocean both at Waha`ula and at Kamokuna, about half-a-mile (900 m) to the west. Both entries have formed lava benches, where new land is building out beyond the former seacliffs.

Inside the crater of Pu`u `O`o, a vent on the west side of the crater floor is active most of the time. Flows from this vent sometimes drain through holes in the crater floor and at other times form a pond in the eastern half of the crater. Several times between mid-June and early August, the pond rose until it overtopped the crater rim to both the west and east. It's been more than a month since the last such overflow took place.

Eruption-viewing opportunities change constantly, so those readers planning a visit to the volcano should contact Hawai`i Volcanoes National Park for the most current information. Visitors should be aware that the lava benches at the coast can collapse into the sea without warning. No one should venture onto the benches, no matter how stable the new land may appear.

Recent Big Island Earthquakes

There were no felt earthquakes reported during the week.