Volcano Watch — Rock piles tell stories we don't want to hear

Stories of older eruptions must be based on just rocks.

These stories are continually refined, hypotheses are tested, and improved stories are constructed. But these continual improvements are possible only if the rock evidence is left undisturbed.

A good example of this combination is the set of stories of the explosive eruptions of Kīlauea volcano.

The most recent explosive eruptions occurred in 1924. The story of this eruption comes from eyewitness accounts, photographs, and the rock debris exploded out of Halema`uma`u during the eruption.

The previous explosive eruption happened about 1790. It is chronicled in Hawaiʻian stories about the annihilation of a substantial portion of an army of warriors making their way back to their home in the Ka`u district. No photographs exist, but there is plenty of physical evidence in the abundant deposits of rock pulverized by the explosions.

For a long time, that evidence was interpreted as the product of a single eruption that occurred around 1790. Recently, a reexamination of that same evidence has led to an expanded interpretation. Those layers of explosive debris were produced over a span of about 300 years, substantially changing the story. The 1790 explosion may have been the last, or one of the last, of many such eruptions.

The stories of earlier explosive eruptions are based solely on physical evidence.

A primary reason that Hawai`i Volcanoes National Park exists is the preservation of natural features of much of Kīlauea volcano, including the rocks. The features are preserved for the enjoyment of present and future generations.

The National Park should be an ideal place to decipher stories about ancient volcanic events from the rocks.

But there's a complication. Visitors to the park may have noticed that, at many stops, rock piles seem to have sprung up - many rock piles. These are not trail markers. Rock piles seem to be concentrated at three popular stops: the Southwest Rift Zone/1971 lava flow, Halema`uma`u, and the 1982 lava flow. These rock piles were not the result of any geologic process, but were, rather, the handiwork of a few visitors.

The visitors sometimes gather the stones used in constructing these piles from a large area. Some of the stones were pried off the surface of nearby lava flows. In the process, they are substantially disturbing, if not destroying, the physical evidence of past geologic events. The rocks are still there, but their story value has been lost because they have been broken and/or moved. The construction of rock piles erases geologic history.

Hawai`i National Park recognizes that rock-pile building is a serious threat to its preservation mission and is focusing efforts to stop the practice. Rock-pile building not only destroys physical geologic evidence, but it could also destroy important archaeological evidence of Hawaiʻian use. They erase Hawaiʻian history. Some liken the practice of rock-pile building to graffiti on the landscape.

Preservation of natural features in their natural state is crucial if we wish our children and their children to directly experience park features. If this practice is not stopped, our grandchildren may only be able to experience rock piles - and that's a story no one would be proud to pass on.

To paraphrase an often-repeated slogan, just say "no" to rock piles.

Volcano Activity Update

During the past week, the count of earthquakes located beneath Kīlauea remains at low levels. Inflation continues, but has slowed over the past two weeks.

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater and on the southwest side of the cone. Lava continues to flow through the PKK lava tube from its source on the flank of Pu`u `O`o to the ocean, with only a few surface flows breaking out of the tube. In the past week, flows were active on the steep slope of Pulama pali, and visible at night (weather permitting) from the end of Chain of Craters Road.

As of November 3, lava is entering the ocean at East Lae`apuki, in Hawai`i Volcanoes National Park. Small bench collapses continue to occur at the ocean entry. Large cracks cross both the old and new parts of the bench. Access to the ocean entry and the surrounding area remains closed, due to significant hazards. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

There were three earthquakes reported felt on Hawai`i Island within the past week. A magnitude-1.6 earthquake occurred at 2:44 p.m. on Thursday, October 27, and was located 1 km (1 mile) southeast of `O`okala at a depth of 38 km (24 miles); it was felt in Hawaiʻian Paradise Park. A magnitude-2.6 earthquake occurred at 11:44 p.m. on the same day, and was located 9 km (6 miles) southeast and offshore of Captain Cook at a depth of 10 km (6 miles); it was felt in Captain Cook. A magnitude-2.1 earthquake occurred at 10:52 p.m. on Saturday, October 29, and was located 7 km (4 miles) southwest of Pu`u `O`o crater at a depth of 8 km (5 miles); it was felt in Fern Acres.

Mauna Loa is not erupting. During the past week, the count of earthquakes located beneath the volcano remains at low levels. Inflation has resumed after having slowed over much of the previous month.