(CNN) There's no way to stop lava.

Once fissures open and the hot stuff starts flowing, it's best not to fight nature.

"The flows cannot be stopped, but people have tried in the past," said Benjamin Andrews, director of the Global Volcanism Program at the Smithsonian National Museum of Natural History.

An unidentified man gets close to a lava flow on a road Monday near Pahoa on Hawaii's Big Island.

Flows can and have been diverted though. The most famous example, Andrews cites, was in 1973 when the Eldfell volcano exploded on Heimaey , a small island in Iceland.

"In that event, huge pumps were used to spray the advancing lava with seawater -- but this effort did not stop the flow, rather it redirected the flow and prevented it from inundating the harbor," he said, adding that portions of some towns were overrun with lava. One person died as a result of the eruption.

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