25 years since Mauna Loa's last eruption

Mauna Loa fire fountains in 1984

For those of you looking for some non-Redoubt-related volcano news, you can take a look at the 25th anniversary of the last eruption at Mauna Loa (there is some nice video footage provided by KHNL if you follow the link). By no means is this volcano "dormant", but rather this is a typical lull in activity at the Hawaiian shield volcano. Its neighbor, Kilauea, has been erupting for decades, but the last major eruption at Mauna Loa was in 1984, when the volcano sent lava downslope with 3,000 feet of Hilo, moving 15 miles in a few days. Monitoring at Mauna Loa has been increased dramatically since the 1984 eruption so that scientists at the Hawaiian Volcano Observatory (HVO) don't get caught by surprise the next time Mauna Loa erupts. If you feel like reliving (or just living) the 1984 eruption, a DVD has been released to commemorate that eruption called "Rivers of Fire" (many of you might have seen this on VHS, but now its out on DVD).

More like this

whoops, that first link was the 1960 eruption of Kilauea, sorry!

One thing to keep in mind is that Mauna Loa's flows are typically much more voluminous and travel greater distances than those from Kilauea. My map of the Big Island shows that some of the flows north of Kailua Kona came not from the nearby volcano Hualalai, but from Mauna Loa. A good portion of the island south of Mauna Kea is in potential reach of Mauna Loa flows.

I'm not certain, but I think 25 years is a long repose time for ML, so we may see some action there soon.

there is a remarkable video on YouTube of Mauna Loa erupting - it's titled "1930s eruption" although it's certainly the one in 1940, and most amazingly it's in full color. Here's the link:


by the way, that was a summit eruption, which might be the type of the next eruption to expect at Mauna Loa before it makes another massive flank eruption.

As for the current repose period, it is now believed that the high levels of activity at Mauna Loa in the period from the 1840s to 1950, with eruptions occurring every few years, was exceptional in the recent geological history of this volcano. Repose periods like the current one or even longer appear to be more characteristic of the past few thousand years. If you happen to find a copy of the book "Mauna Loa Revealed" by the American Geophysical Union (published in 1995), there's quite a lot of interesting reading in there, including the statement that we should not infer on the future from the relatively short (<200 yr) historical record.

Certainly, the next Mauna Loa eruption will be a great show!

You make an excellent point about repose times over long periods, this shows the weakness of just relying on the historic record. And the historic record in Hawaii is very short indeed compared to age of Mauna Loa. We definitely need to look at the geologic record to determine the true eruptive pattern of any volcano. This of course requires painstaking examination of the field geology, petrology and geochemistry of the volcano, and such research is as important in the study of volcanic hazards as monitoring current conditions.
Alas, too many academic departments no longer teach much in the way of petrology, mineralogy, gechemistry and field geology, saying that "no one does that anymore" and the "field has changed". IMHO such attitudes have done more damage to the advancement of geologic knowledge than anything a politician or pundit has said.