Volcano Watch — Kīlauea flows are large

The eruption along Kīlauea's east rift zone continues without interruption. The lava is erupting from two vents, which we call the episode 51 and 53 vents, located on the west and south flanks of the Pu'u 'O'o cone, and transported downslope in a long-lived tube system. The vents have collapsed and are now deep pits; the spatter cones formed during the initial fountaining episode have collapsed into the pits. At times, the bottom of these pits contain lava, but most of the time there is none visible and no glow at night; however, the pits are sources of substantial gas emissions. The lava pond inside the Pu'u 'O'o cone is active but nearly 300 feet below the lowest part of the crater rim.

The last brief pause took place on Sunday, March 13, immediately following the formation of the spatter cones at the ocean entries the previous week. The eruption restarted slowly on March 14 and took several days to build up to large volume and for the flows to reach the ocean once again. Since that time, the volume has been larger than we have seen at any time during the last few years, reaching a peak of about 600,000 cubic meters per day during the last days of March. Since that time, the volume has decreased slightly, although it is still in the range of 500,000 cubic meters per day.

The large volumes have resulted in multiple ocean entry sites; on April 13 there were seven separate ocean entry zones. In addition, the tube system has been unable to transport such large volumes, and there have been numerous surface breakouts from the tube at elevations from above 2,000-feet elevation to areas below Paliuli near the coast. On April 13, at the same time, there were the seven ocean entries, and four separate surface lava flows issuing from breaches in the tube.

During most of this period, the activity where the lava enters the ocean has been passive, with few explosions and rather small-scale spattering. However, this past week has seen an increase in explosive activity, as recorded on a seismic station near Kamoamoa. Since the formations of coastal spatter cones in early March, several steam explosions have hurled large lava blocks onto the lava delta and newly-formed lava ledge.

The many lava entries have added a large area of new land along the coast. This newest land extends from the eastern edge of the flow field at Kamoamoa to near the middle of the Laeapuki flow, a zone nearly a mile-and-a-half wide. Much of this coastline has had new land added to its margin. The flows have also extended far from the old coastline with the edge of newest land now located some 50 yards seaward of the spatter cones formed in early March. This zone of newest land we call the lava bench or ledge because it is usually separated from the older lava delta by a steep scarp that used to be a sea cliff. These ledges are unstable because they are built on top of black sand and lava fragments; they commonly slide into the ocean with little or no warning.

We urge visitors to Hawaii Volcanoes National Park who want to watch this activity at the coast to obey the warning signs posted by the National Park Service and to keep a safe distance away. The entire area is extremely dangerous, and explosions and spattering of widely variable intensity occur without warning, as do collapses of the youngest lava ledge. Because the present ledge is so large, we anticipate that another major collapse could occur, with large parts of the ledge, perhaps including the three spatter cones, sliding into the sea.

The National Park Service has posted warning signs around the most dangerous areas. Other areas near the coast may also be dangerous but signs have not yet been posted because the lava activity shifts rapidly from place to place along the coast. These signs have a skull and crossbones symbol and tell you to stop. They also enumerate the dangers that lurk beyond the sign and remind people that one visitor was killed and 14 other injured during a collapse of the lava ledge that occurred one year ago on April 20. If you visit the coastal area and reach these signs, you are risking death or serious injury, and you are also in violation of federal law because the area is closed by order of the Park Superintendent. Our Observatory personnel wear hard hats, sturdy boots, and long pants and carry gas masks and a radio when they enter these areas to monitor the activity. In addition, we minimize the time spent in these dangerous areas.