Construction and Collapse
of New Land Continues at Kamokuna

This update is current as of December 16, 1998.

View of new land toward west, SE coast of Kilauea Volcano
Photograph by J. Kauahikaua on December 11, 1998

A large part of the active lava delta on the southeast coast of Kilauea Volcano collapsed into the sea sometime between noon December 10 and 9:30 a.m. on December 11. A comparison between the shoreline mapped on November 11 (white line in photo) and the shoreline on December 11 (shoreline in photo) shows that the total land lost was about 5.8 ha (14.5 acres).

The missing shoreline includes 3.4 ha (9.2 acres) from land built into the sea since August and about 2.4 ha (5.3 acres) from land built between 1992 and 1997 west of the current lava-entry area (toward top of photo). Volcanic fume rises from skylights above the lava tube (red) that is supplying lava to sea.

Overview

The eruption of Pu`u `O`o continues to deliver lava to the sea through a lava tube that developed on the coastal plain after a pause in magma supply to the vent on August 12-14, 1998. A brief pause on November 7-8 (pause 21 of the current eruptive episode) led to several small `a`a and pahoehoe flows on the coastal plain, but none reached the sea. In the past several weeks, scientists have measured a slight increase in the discharge of lava through the tube system--from less than 300,000 m<sup>3</sup>/day in October to just over 400,000 m<sup>3</sup>/day in early December. Dense volcanic fume continues to obscure various pits within Pu`u `O`o most of the time, but sloshing sounds of lava degassing can be heard from the crater rim.

Visitors Use Caution:
Former Sea Cliffs Covered by New Lava

View toward N; November 24	View toward W; December 11
[Medium-sized image] [Large-sized image]	[Medium-sized image] [Large-sized image]

When lava began pouring into the ocean 300-400 m west of the prominent littoral cone (left photo) in late August, the former shoreline and sea cliff were quickly covered with many thin flows. The old cliff became nearly impossible to identify landward of the new lava-entry area, which made it difficult for visitors to determine relatively safe areas from which to view the lava-entry area. Sometimes visitors ventured out onto the new land not realizing they had crossed the old cliffline and were walking on unstable and dangerous ground.

In the images above, the approximate location of the old sea cliff is marked with a yellow line. Note that on December 11, the shoreline actually was inland from the old cliff--the collapse event of December 10-11 removed the new land that had been built since August and a part of the older shoreline. This slightly older shoreline was built by lava between 1992 and 1997. Clearly, even the older shoreline is susceptible to collapse when an active lava delta and bench collapse into the sea.

Judging from earlier bench collapses, the missing area most likely slid into the sea in several segments over a period of at least several tens of minutes to several hours. If you happen to be viewing the area when parts of an active lava bench begin to collapse into the sea, make sure that you are already, or retreat to, at least 400 m inland from the former shoreline (as recommended by Hawaii Volcanoes National Park).

Newest Pit on Pu`u `O`o Enlarging Slowly

The new pit that developed high on the south flank of Pu`u `O`o vent about one year ago enlarged significantly in early 1998, and recent measurements of cracks around the edge of the pit show that its walls are slumping slowly into the pit.

	December 9, 1997 Near-vertical view into newly formed pit on south flank of Pu`u `O`o. Pit is 50 m in diameter at the surface and about 50 m deep, tapering to a shaft of uncertain depth.
[Medium-sized image] [Large-sized image]

	November 11, 1998 The pit is 150-180 m in diameter and has consumed part of the shield at the base of Pu`u `O`o. In the past few weeks, the pit enlarged so that its upper edge nearly reaches the crater rim of Pu`u `O`o. The pit is becoming shallower as more debris slumps in from its walls.
[Medium-sized image] [Large-sized image]

Flow-field Map

Map showing area covered by lava flows emplaced during the Pu`u `O`o - Kupaianaha eruption between 1983 and August 30, 1998. Flows emplaced between August 14 and August 30 are shown in purple. A new lava tube has developed within this flow field and is delivering lava to the sea 300-400 m west of the east Kamokuna lava tube (black line). On October 19, a surface flow moving from the base of Pulama Pali reached the sea about 400 m west of the the area shown in purple.

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 eruption information (ph. 808-985-6000).