[ TEXT ONLY ]
USGS
Hawaiian Volcano 
Observatory

Kilauea
Eruption
Summary

Hazards
History

Mauna Loa

Earthquakes

Other Volcanoes

Volcanic Hazards

Kilauea

Pahoehoe Creates New
Ocean-Entry Area

This update is current as of September 4, 1998. Eruption updates are posted every 4 to 6 weeks; more frequent updates will be made when there are drastic changes in activity or when residential areas are threatened by lava flows. Update archive.

Aerial view of new pahoehoe flows and ocean-entry point Photograph by J. Kauahikaua on September 3, 1998

Aerial view to south shows pathway of new pahoehoe lava (shiny surface, foreground) that reached the sea on August 30. The new entry area is about 300-400 m west (right) of the long-established east Kamokuna entry (left steam plume rising from beyond littoral cone, which is fed by a lava tube).

Overview

Lava continues to erupt from vents on the southwest flank of Pu`u `O`o and travels 12 km to the coast through lava tubes. Lava breakouts from the tubes, following a pause in magma supply to Pu`u `O`o on August 12-14, led to a new pahoehoe flow at the base of the pali. The flow front was about 500 m from the shoreline on August 25 and reached the sea five days later. The broad flow is slowly inflating and a new lava tube is developing within the flow. Both the new tube and surface flows deliver lava to the sea at the new entry area.

Lava has been spreading as many small pahoehoe toes from along the margins of the new flow upslope from the shoreline. The new flow is extremely hot and makes the approach from the west difficult and hazardous (west access is from the end of the Chain of Craters Road in Hawai`i Volcanoes National Park). Lava at the new entry intially poured over a sea cliff created by a previous bench collapse and onto a black sand beach. Both entries are adding new lava to the Kamokuna bench. Visitors should be wary of collapses and explosions that can occur suddenly along the growing lava bench.

Lava breakouts follow August 12-14 pause

Twenty pauses lasting from a few hours to a few days have occurred so far during Episode 55, which began in March 1997. These short-term interruptions in magma supply to Pu`u `O`o result from one or more blockages in the conduit system between the summit magma reservoir and Pu`u `O`o. The most recent pause (No. 20) began on August 12 and lasted approximately 42 hours, during which time Kilauea's summit inflated about 2 microradians. The slight inflation indicates magma was still rising into the summit reservoir but not moving into the east rift zone.

When lava emerged again from Pu`u `O`o and flowed back into the tube, several flows broke out on the pali and at its base. The largest flow originated from the same breakout point that was active following a pause in July.

New lava tube develops in lava breakouts

Lava travels through new lava tube on its way to sea
August 27. Close view of lava flowing through a new shallow lava tube that developed in lava-flow breakouts following pause No. 20. Lava from this tube fed the pahoehoe in the image below. The skylight is located just out of view in the upper left of the next image at an elevation of 150 m above sea level.
[Medium-sized image] [Large-sized image]

Pahoehoe marches to the sea

Aerial view of Kamokuna entry point and pahoehoe lava flows approaching the sea
August 27. Aerial view of the single Kamokuna entry point (plume rising from shoreline in lower right) and pahoehoe flow moving toward the sea (light-toned flows in center). Leading edge of the flow is about 300 m from shoreline.
[Medium-sized image] [Large-sized image]

Surface flows and new lava tube deliver lava to sea

Aerial view of two lava-entry points along Kamokuna bench
September 3. Aerial view of southeast coast of Kilauea Volcano. Diffuse plumes mark locations of the two lava-entry points (top one is older entry). A small plume visible at the base of the littoral cone rises from a lava tube.
[Medium-sized image] [Large-sized image]

Daily lava-discharge rates from Pu`u `O`o unchanged

Geophysicist conducting survey across lava tube
September 3. Geophysicist conducts a survey across the lava tube (note red skylight) before it pours over the pali and splits into two tubes. Surveys in the past few weeks indicate that about 250,000 m3 of lava per day travels through the tube from Pu`u `O`o; since March, scientists have measured average daily lava discharge of about 300,000 m3. These estimates are determined by measuring the cross-sectional area of the tube and the velocity of the lava moving in it.
[Medium-sized image] [Large-sized image]

New collapse center at Episode-55 spatter cone

Seismologists noted a series of more than two dozen seismic signals localized at Pu`u `O`o on August 26. The signals had a frequency lower than is typical of that for most earthquakes, and they were likely caused by the partial collapse of a spatter cone located on the west flank of Pu`u `O`o.

Aerial view of Episode 55 spatter cone
August 27. Aerial view of the Episode 55 spatter cone located on the west flank of Pu`u `O`o (out of view to left). The low notch represents a missing part of the cone that collapsed, probably on the previous day.
[Medium-sized image] [Large-sized image]

Episode 55 spatter cone
September 3. By September 3, the crater atop the spatter cone had grown to about 50 m in diameter.
[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 is developing within this flow area and is delivering lava to the sea 300-400 m west of the east Kamokuna lava tube (black line).

Update Archive


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).

Additional photographs and descriptions of the Pu`u `O`o - Kupaianaha eruption may be found at:

HomeVolcano WatchProductsPhoto GalleryPress Releases
How Hawaiian Volcanoes Work

The URL of this page is: http://hvo.wr.usgs.gov/kilauea/update/ Contact: hvowebmaster@usgs.gov
Updated: 4 September 1998