Mauna Ulu

Mauna Ulu first erupted in May 1969 and would continue for the next five years. In the course of those eruptions lava would occasionally fountain over 1,700ft high while flooding much of the surrounding area, eventually constructing a lava shield nearly 400ft above the original ground level.

In many ways the Mauna Ulu eruption was very similar to the Pu‘u ‘Ō‘ō eruptions that would start a decade later and continue for well over three decades. It is the Pu‘u ‘Ō‘ō eruptions that formed my first memories of Kilauea with television news of homes burning in the Royal Gardens subdivision and visits to the ocean entries at Kalapana. While Pu‘u ‘Ō‘ō remains somewhat remote, Mauna Ulu is far more accessible.

Having looked up at Mauna Ulu a fair number of times I had wanted to get a closer look at this volcanic edifice. Thus a visit was on the top of my list for exploration when I had a day in the park. Visiting the top of the adjacent Pu‘u Huluhulu, a much older and heavily forested cone would be part of the excursion. It is only a one mile walk from the trailhead to the two vents, from there I would spend the time hiking around and climbing to the top of both.

In contrast to the barren rock of Mauna Ulu, Puʻu Huluhulu has a mature ‘ōhi‘a forest softening its once jagged form. A large crater forms a forested canyon from which a chorus of native birds sing. Aside from time it appears that there is very little difference between Puʻu Huluhulu and Mauna Ulu… About the same size, a similar style of eruption resulting in a similar shape and very similar crater.

An excellent view of Mauna Ulu can be found from the summit of Puʻu Huluhulu 650 yards north where a nice viewpoint exists at the end of a short trail. The lava shield looks quite fresh, as it stopped erupting a few years ago rather than a few decades. The view also overlooks an excellent example of a perched pond that sits at the north base of Mauna Ulu, a flat shelf with a notable rim of built up lava complete with lava falls now frozen in place.

Getting to the top of Mauna Ulu is quite easy, the very hot pahoehoe lava that spilled out from the summit crater left a smooth surface that is not much more difficult than a wheelchair ramp to ascend.

Reaching the top one is greeted by a yawning crater, a spectacular chasm that spans about 500ft with sheer walls that drop about the same distance. One is well advised to stay well back from this crater edge, this is a very unstable area as can be attested by the large cracks found around most of the rim.

Mauna Ulu is not totally barren, a scattering of small ‘ōhi‘a and pūkiawe shrubs dot the black lava slopes, struggling in the harsh environment. In time these will form a forest as found on the adjacent Puʻu Huluhulu, but that time is a long ways off.

The slopes are also rich in eruptive features… Lava channels, pāhoehoe bubbles, the already mentioned perched pond with lava falls, pāhoehoe and a‘a lava flows, one could illustrate a vulcanology textbook simply walking around this one lava shield.

I spent quite some time walking this way and that, if I plotted my path across the cone it would look like a drunkard’s walk as I randomly changed course to check out some lava feature or intersting plant, or to take another photograph. Then there were places where a lava channel or dangerous shelly pāhoehoe blocked the path and I was obliged to find a way around.

A very satisfying outing, goal accomplished and just as interesting as I had hoped. On to the Ka‘u Desert tomorrow!