Pele Meets the Sea

Part II: Still Photographs of Active Lava

Under water lava flows

Studying moving lava flows underwater in Hawaii provides a rare opportunity for scientists to see how quickly the lava flows are quenched by the ocean, and how this cooling affects the appearance of the lava. Here we see just a few of the views captured by the University divers.

Close to the active lava, our diver finds that pillow basalts form from relatively slow moving submarine lava flows. This slow movement allows the overlying seawater to rapidly cool the molten lava, which causes a surface crust to quickly form, giving the resulting rock its distinctive pillow shape. Large numbers of gas bubbles are released from the pillow basalts while they form. These bubbles are distinctive in that they contain relatively high levels of explosive hydrogen gas, which is formed by the chemical reaction of sea water with the hot lava.

The formation of pillow lava underwater is accompanied by a steady stream of sounds. Some are the result of fracturing of the cooling crust and the implosion of the solid pillows. Other loud explosions result from the combustion of hydrogen trapped under the cooled outer skin of the lava flow.

It is also fascinating to see growing hot lava flows under water. Some of the pillows observed at Kilauea are exceptionally fluid, and form long toes such as the one seen here that have a central crack that propagates the growing toe of incandescent lava.

It has been generally assumed by geologists that underwater lava flows always produce pillows. However, at Kilauea we have seen other types of underwater flows. These are fast-moving flows, similar to the channelized lava flows observed on shore, and are fed by tubes that open directly onto the seafloor.

Violent hydrogen explosions and jets of hot water can frequently be seen along the larger active underwater flows below the mouth of the lava tube. These explosions and hot springs are the results of sea water seeping down into the seafloor and coming in contact with buried lava tubes. The temperature of the jets is near the boiling point of water, as indicated by the steam they vent. The jets are also another source of hydrogen-rich bubbles.

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Diving and video movie: Richard Pyle, Jane Culp, Frank Sansone, Gordon Tribble, Jane Tribble, David Schideler, Kevin Kelly, John Earle, Randall Kosaki;Copyright 1990 LavaVideo Productions, 741 N. Kalaheo Avenue, Kailua, HI 96734.

Digitization and HTML presentation: Cristina Lumpkin and Pierre Flament

To see some related photos and for references to some more information that may be of interest, please check out the link to Frank Sansone's web page on our Project Linkspage.