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Volcano watch: Kalapana lava delta collapsed last week

Photo of the Puhi-o-Kalaikini lava delta taken Thursday, Oct. 28, 2010, prior to the collapse. The red line shows the approximate inland boundary of the area that collapsed into the ocean Nov. 2. (Photo courtesy of USGS)

(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory.)

The Puhi-o-Kalaikini lava delta in Kalapana abruptly shed its western edge last week – no injuries or deaths this time.

The Puhi-o-Kalaikini lava delta, which will be four months old later this month, currently stretches along the coast for about 1 km (0.6 miles) and protrudes about 150 m (490 ft) or so out from the pre-eruption coastline. Its surface area is about 9.3 hectares (23 acres).

At around 5:30 a.m. Nov. 2, a sliver of the western seaward edge delta, about 350 m (1150 ft) long and up to 40 m (130 ft) wide, collapsed abruptly into the ocean. The delta had been sporting two distinct entry points along this edge before the collapse. Afterward, there was but one.

The night before, and for most of the nights and mornings in the last few months, groups of visitors have been trespassing on State of Hawaii land to see the wonders of an active ocean entry.

Some, if not most, get right up to the edge of the delta to get the best view. Their perch was the same edge that slid into the ocean Nov. 2.

At least one unsuspecting person was out on the delta less than an hour after the early morning collapse.

Scientists at the Hawaiian Volcano Observatory repeatedly warn that an active lava delta, one where lava is entering the ocean (like Puhi-o-Kalaikini), is the most hazardous area on the coastal plain. This high hazard rating was earned by the delta’s predisposition to collapse into the ocean without warning.

It may seem like an obvious statement but it bears saying again – the only 100 percent effective way to prevent injury or death by delta collapse is to keep all people off an active delta 100 percent of the time. Disregard of such vigilance has already resulted in injury and a few deaths.

An analogous hazard situation would be a busy road. We all know that it can be dangerous, and potentially fatal, to cross a busy road. Many of us do so anyway secure in the belief that we can avoid oncoming cars. Walking out onto an active lava delta, however, is like crossing a busy road when you cannot see or hear the cars coming.

Deaths have resulted from being on an active lava delta. A recent Volcano Watch article ( ) reminded us of the grizzly details where curiosity ended in death for four people who ventured out onto an active Kilauea lava delta at the wrong time. There is no known way of judging the right time.

The ongoing Kilauea eruption has produced more than 100 individual lava deltas each ranging in size from a few square meters to about 100,000 square meters (10 hectares or 25 acres). Each of the larger deltas has collapsed several times.

The combined contribution of all these deltas during the entire eruption so far, minus the eroding action of waves, is an increase in the area of Hawaii Island by more than 190 hectares (470 acres).

For the current delta, the narrow embayment created by the Nov. 2 collapse has already begun to fill in. This will only add to the potential for collapse that exists already as long as lava continues to enter the ocean.

3 Responses to “Volcano watch: Kalapana lava delta collapsed last week”

  1. Leigh says:

    I witnessed this bench collapse and videoed the entire event, which lasted thirty minutes. I posted both still photos and a 4-minute movie clip that can be viewed on my Hawaiian Lava Daily blog or on YouTube:
    I was the only person in the area at the time, though on other early mornings there I have seen people out along the lava flowing edge of the delta. I shot the footage from the old trail just a few feet off the forested edge of the newly forming delta/bench at 5:24 AM November 2nd.

  2. Bryan says:

    It was a relatively small collapse compared to the many larger ones I’ve seen in the past 19 years. Had it been much larger many of the clueless tour guides and their even more clueless clients would have died. I wouldn’t doubt they are right back out there now. It will collapse more soon enough.

  3. Midnight Rambler says:

    In truth, a better analogy would be crossing a rarely-travelled road where you can’t see or hear the cars. Most of the time, nothing happens, because there are so few cars. But when one does come, you have no way of knowing, and that’s it…


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