Volcano Watch — Eruption's flows continue, danger remains

The eruption on Kīlauea's East Rift Zone continues with little change. The episode 51 and 53 vents on the southwest flank of the Pu`u `O`o cone continue to feed lava directly into a tube system that transports the lava to Palama Pali and beyond, to the ocean entries at Kamoamoa. 

During the past week, the volume of lava entering the sea has fluctuated, depending on the occurrence of surface flows on the pali. From a distance, the surface flows can be viewed from the end of Chain of Craters Road in Hawai`i Volcanoes National Park. The view is particularly good at night, when each area of new lava can be seen. The lava pond inside Pu`u `O`o cone is active and about 260 feet below the rim, as it has been since the eruption started again on February 16.

The flow that covered Lae`apuki is now inactive, but lava continues to enter the sea at three points on the east side of the Kamoamoa flow field. However, the area where lava enters the sea at Kamoamoa is located about 1.25 miles from the end of the road, and the National Park Service is limiting access because the hike is across young, hot flows. 

In addition, violent interaction of lava and seawater continues to occur, resulting in another large steam explosion at the main lava entry point within the last week. This explosion hurled lava blocks as large as 3 feet in diameter up to 300 feet from the coast, and threw smaller fist- to football-sized blocks nearly twice as far. Fortunately, no one was injured by these ballistic blocks, as the explosion occurred when no visitors were present. This explosion is similar to one that injured nearly 20 visitors several weeks ago, when the then-active lava bench along the coast at Lae`apuki collapsed, killing one visitor. 

The flow of lava into the ocean is focused at one main point, where a low littoral cone has formed from accumulated spatter and lava ribbons. The cone is perhaps 75 feet across and is shaped like a half-circle, open towards the sea. An earlier littoral cone was dissected by a bench collapse, and a small remnant is perched on the edge of a former sea cliff, roughly 10 feet above the most recent bench. The newest bench along the coast, and the one with the littoral cone, is at least 300 hundred feet long and about 50 feet wide. 

Offshore from the lava entries, ocean water is heated by the lava, and a large, discolored plume of water can be seen. The discoloration is mainly caused by suspended, fine particles of lava. Close to shore the sea water often appears to be boiling, but the turbulence is probably caused by gas bubbles of hydrogen produced as the lava reacts with the sea water. These hydrogen bubbles ignite and explode, producing a glow in the water at night. Lava entering the ocean is mainly shattered into sand-sized fragments, which form new black sand beaches. However, most of the sand is transported offshore and down the steep submarine slope to deeper water. Other lava that flows into the ocean forms spatter-like blobs of lava that float on the surface of the water while they are still hot. Many of these bubble-rich lava fragments wash up on the beach and are then broken up to sand- and gravel-sized fragments by wave action. 

The steam cloud at the ocean entries (laze) consists of steam and hydrochloric acid, produced from the chloride in seawater, and small particles of glass produced from the shattering of hot lava when it is quenched by seawater. In addition, degassing of the lava in the tube system and at the ocean entries releases sulfur dioxide gas, which combines with water to form sulfuric acid. Some of the sulfur is also precipitated in cracks in the lava.

The ocean entry area remains extremely dangerous because of the occasional lava bench collapses, steam explosions, variable spattering heights at the littoral cone, and fume. Visitors should obey the warning signs and area closure signs posted by the National Park Service - these signs and warnings are placed to keep visitors away from dangerous and unpredictable locations and situations.