The Puu Oo vent at Kilauea on the Big Island flowed with lava in July 1983.

Lava flow suggests
Big Isle volcanoes linked

Mauna Loa activity may have
influenced Kilauea, scientists say

By Rod Thompson

HILO >> Two events in May have geophysicists at the Hawaiian Volcano Observatory thinking that Mauna Loa can affect how neighboring Kilauea volcano erupts.

That runs against the prevailing idea that the two volcanoes are completely separate except at great depths.

After a long period of slight shrinkage, Mauna Loa began to swell slightly in May, indicating magma was flowing into its innards from deep in the earth.

At the same time, a new, high-volume output of lava called the "Mother's Day flow" began at neighboring Kilauea.

The chances of the two events being a coincidence are less than one in 10, observatory geophysicist Asta Miklius wrote in today's edition of Nature magazine.

"Here is a very unexpected observation," said Miklius' colleague, geophysicist Peter Cervelli.

But what the observation means is not clear to either Miklius or Cervelli.

All the Hawaiian Islands were created by a single "hot spot" about 60 miles deep. But near the surface of the earth, magma from the two volcanoes is not believed to mingle, as shown by the fact that lavas from the two volcanoes have different chemical compositions.

So how did Mauna Loa influence Kilauea in May? The best guess by Miklius and Cervelli is that a "pulse" of magma moved into Mauna Loa, making it bulge against Kilauea.

Kilauea was already stuffed with its own magma, so Mauna Loa's pressure forced Kilauea to cough up a hefty new flow, they said.

Miklius and Cervelli said they cannot completely rule out the possibility of a single pulse of lava bloating both Mauna Loa and Kilauea.

In other words, the two mountains may share a single magma chamber somewhere not too deep underground, although that runs against evidence favoring separate magma chambers.

Miklius said she put the idea in the Nature article because it is at least possible. But she added, "We have no direct evidence for a shared pulse of magma."

She prefers the word "interaction" to describe the relationship of the volcanoes.

And the immediate meaning for Mauna Loa and Kilauea eruptions? Not much. The Mother's Day flow is still going, while the slight hints of a future eruption on Mauna Loa have slowed down.

Hawaii Volcanoes National Park

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