Volcano Watch — Dramatic changes at Kīlauea

Kīlauea's east rift zone eruption at Pu'u 'O'o, which began in January 1983, continues. Lava is actively circulating in a pond inside the Pu'u 'O'o cone. The pond is at a depth of about 79 meters below the lowest point on the rim of the cone. There has been little change at the cone for several months. Lava continues to erupt from two vents located on the south and west sides of the cone, although lava is not visible in either area because it is fed directly into a complex underground tube system. Heavy fume, consisting mainly of sulfur dioxide and water vapor, is emitted from the lava pond and from the two vents. Additional sources of fume include a number of openings, or skylights, in the top of active lava tube. At several of these skylights, the active flow can be seen from the air.

Downslope of the vents, there have been some dramatic changes within the last few weeks. The most significant change has been the breakout of a series of flows from the tube starting at about the 1,100-foot elevation. These flows were initially 'a'a, but have since been overtopped by pahoehoe. On Thursday, there were three moderately sized 'a'a flows advancing down the central and eastern parts of the Kamoamoa flow field. The easternmost flow was burning vegetation along the margin of the flow field at an elevation of about 500 feet.

The volume of lava in the tube above 1,100 feet remains high, with an estimated 500,000 cubic meters per day of lava flowing through the tube. Below the 1,100-foot level, the volume varies depending on the breakout of new surface flows. Occasionally all the lava comes out as surface flows and the ocean entries briefly stop. On Thursday, the volume entering the ocean varied from none to nearly all the volume in the tube. As the flow through the tube waxes and wanes, the steam plume at the ocean entries varies greatly. However, the activity at the ocean was very confined with lava entering the ocean over a narrow area (perhaps 20 feet wide). There are episodic small explosions as lava and sea water mix.

The actively growing lava bench continues to slide rapidly seaward; it is moving at up to about 2 inches per day. This rate of movement and extension of cracks in the bench is not as fast as we have measured previously, but still indicates that part of the current lava bench will probably collapse into the ocean as a small landslide in the near future.

We have been recording an intense swarm of small earthquakes beneath the summit of Kīlauea for the last two weeks. These earthquakes are related to movement of magma and indicate that more magma is moving up into the volcano. This has been the longest and most intense swarm of such earthquakes in several years. We are also recording an increase in the volume of magma stored under the summit, as seen in subtle changes in the tilt of the ground around the summit region. These changes indicate that more magma is being delivered to Kīlauea's shallow magma reservoir than is presently being erupted. In the past, such swarms of earthquakes have preceded increases in the eruption rate and formation of new surface flows. We may already be seeing some of this increased volume with the new surface flows.

Lava entering the ocean may be safely viewed from within roped-off areas at the end of Chain of Craters Road, since the lava is entering the ocean only a few hundred feet from the old sea cliff. The surface flows are currently on steep slopes and can advance rapidly and unexpectedly. When they get to lower elevations and flatter ground, the flows can be approached more safely. There are many hazards around the lava flows and you are advised to check with the Park Service about viewing conditions and to then stay within the roped-off viewing areas. The Park Rangers continue to issue citations to people who are foolish enough to enter unsafe, closed areas.