Posted on: Friday, November 22, 2002

Mauna Loa eruptions aren't always tame

Mauna Loa erupts every 10 years or so, and last did so in 1984. Now scientists think it's building toward another eruption.

If you live on the Big Island and missed Neighbor Island editor Christie Wilson's informative report Tuesday on Mauna Loa's gradual awakening, you owe it to yourself and your family to read it.

It's certainly nothing to get panicky over, but we suspect far too many people lack a healthy appreciation for the dangers posed by Mauna Loa and other volcanoes.

For one thing, recent urban growth has crept farther up the slopes of Hawai'i volcanoes. For another, we've become used to the current Kilauea eruption, gently pumping away since 1983. It's nice to have mellow volcanic activity that you can saunter up to for a look. But Hawai'i volcanoes haven't always been that predictable.

The 1950 Mauna Loa eruption sent lava down its Kona side — reaching the ocean in less than four hours — while in 1984, residents worried as Mauna Loa flows stopped not all that far from Hilo's outskirts. Flows in the 1881 eruption would have destroyed parts of present-day Hilo.

Other volcanoes have been inactive for a couple of hundred years, but that's just a blink in geological terms, and they may not be done yet. In 1790, Haleakala reshaped La Perouse Bay on Maui. In 1801, flows from the Big Island's Hualalai, reaching the sea very quickly, built most of the land now under the Keahole Airport. Much of present-day Kailua-Kona is built on Hualalai's flank.

Arnold Okamura, who has been at the Hawaiian Volcano Observatory for 36 years, says he's not trying to scare anyone by announcing that Mauna Loa is inflating. But, he says, it is a good time to remind Big Islanders, particularly those who arrived only recently, just what they could be facing. He's right on track.