November 11, 1994

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

Watching Lava Flows

The eruption along Kilauea's east rift zone is approaching its twelfth anniversary, now less than two months away. The eruption continues strongly, with magma replenishment beneath the summit roughly matching eruption rates. Our latest measurements indicate that about 450,000 cubic meters of lava per day are erupting from the crusted-over vents on the south and west flanks of the Pu'u 'O'o cone. The Lae'apuki tube was active from July 1993 until October 24. Following a brief pause in activity, lava reoccupied only the upper half of the tube system. Near the break in slope at the top of Pulama pali around the 1,950-foot elevation, lava broke out of the old tube and has formed extensive new surface flows along the western side of the Kamoamoa/Lae'apuki flow field. These flows reached the ocean on November 4 after forming spectacular lava falls over Paliuli. The new flows have formed two new lava tubes, one that hugs the western edge of the flow field and a second one that meanders down the pali and supplies lava to the ocean entries at Lae'apuki. The new entries are still broad, and the steam plume is small, because only a small volume of lava is entering the ocean. Most of the erupted lava volume is widening and thickening the flows that advanced down the pali in the past two weeks.

The lava viewing has been excellent, with flows entering the ocean right at the blocked end of Chain of Craters Road in Hawaii Volcanoes National Park. In addition, surface flows have been active at the end of the road past the car turn-around. There are many hazards to be aware of when you go to view the flows. The plume produced where flows enter the ocean does not consist entirely of steam; hydrochloric acid and minute glass particles are also present. The burning asphalt at the end of the road generates toxic fumes that should be avoided. As the flows cover vegetation, methane is produced, and explosions can occur. The methane commonly accumulates beneath older flows adjacent to the active flows, and the explosions can occur beneath these older flows. Blocks of old lava flows, as well as hot lava, can be ejected into the air. Take water along because wind that blows across the active flows will be very hot and dry. It is easy to get dehydrated by this dry, hot wind without even getting close to the active flows. Where the lava enters the ocean and new land is built, sudden small collapses occur that can remove pieces of the lava ledge and produce small tsunami that wash boiling sea water over the lava ledge. Finally, if you go in the evening, take along a flashlight. Most of the injuries that occur in the area are cuts and scrapes when people fall on the new lava. Remember that the surface of the lava is quenched glass that is just as sharp as window glass. Be careful, obey the warning signs and on-duty Park Rangers, and safely enjoy this spectacle of nature.

Last week, we advised you that we were keeping an eye on a series of earthquakes in lower Puna. During the early part of the week, we recorded a few additional earthquakes in the same location beneath Leilani Estates. However, the second half of the week has been totally quiet.

A new exhibit entitled "GLORIA: A Sonar Mosaic of the Hawaiian Ridge" is now on display in Hilo at the Lyman Museum. The sonar images provide total coverage of the geological features on the flanks of the Hawaiian volcanoes and on the sea floor around the islands. The data were collected by the U.S. Geological Survey's Branch of Pacific Marine Geology, located in Menlo Park, California. Dr. David A. Clague, Scientist-in-Charge of the Hawaiian Volcano Observatory and former manager of the Hawaiian GLORIA Project (and author of most of these Volcano Watch columns) will give a public presentation about the results of the GLORIA sonar mapping project around the Hawaiian Islands on Wednesday, November 16, 1994, at 7:00 p.m. at the Lyman Museum at 276 Haili Street in Hilo. Admission is free. If you were ever curious about what lies below the water around the Hawaiian Islands, this is a great opportunity to satisfy that curiosity.