How Hawaii Formed: Internal Emplacement of Magma Wasn't the Cause

It turns out that the Hawaiian Islands may not have formed in the way that we thought they did. Scientists have discovered that the eruptions of lava on the surface, extrusion, were what made the islands. Previously, researchers believed it was the internal emplacement of magma.

Before this study, scientists thought that the Hawaiian volcanoes grew primarily internally by magma intruding into rock and solidifying before it reached the surface. While this type of growth does occur along Kilauea's East Rift Zone (ERZ), it's not representative of the overall history of how the Hawaiian Islands formed. In order to find a little bit more about the islands, though, the researchers examined quite a bit of data.

In all, the scientists compiled historical land-based gravity surveys with more recent surveys on the Big Island of Hawaii and Kauai along with marine surveys from the National Geophysical Data Center. These types of data allowed the researchers to infer processes that occurred over logner time periods.

"The discrepancy we see between our estimate and these past estimates emphasizes that the short term processes we currently see in Hawaii (which tend to be more intrusive) do not represent the predominant character of their volcanic activity," said Ashton Flinders, one of the researchers, in a news release.

"This could imply that over the long-term, Kilauea's ERZ will see less seismic activity and more eruptive activity than previously thought. The three-decade-old eruption along Kilauea's ERZ could last for many, many more decades to come," said Garrett Ito, co-author of the new paper, in a news release.

The findings reveal a little bit more about the Hawaiian Islands. More interestingly, it has implications as to how the intrusive-to-extrusive ratio impacts the stability of the volcano's flank. It's possible that some of the collapses that have occurred over the history of Hawaii could be due to weak extrusive flows.

Currently, the researchers hope that their new density model can be used as a starting point for further crustal studies in the Hawaiian Islands. For now, though, the new study reveals a little bit more about the volcanic activity of the area.

The findings are published in the journal Geophysical Research Letters.