Once the fissures open and the hot stuff starts flowing, it's best to not 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 Nation Museum of Natural History.
Flows can and have been diverted, though. The most famous example, Andrews cites, wasin 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.
In other cases, Andrews said, bombs were used in attempts to divert a lava flow, but that didn't work.
Challenges
Andrews said there were several challenges with stopping lava flow.
For starters, lava is dense.
"It may flow like sticky syrup, but is more dense than cement," he said. This means there's no point in putting up Jersey walls in front of a flow because the lava will "bulldoze them out of the way."
Some have thought to spray the lava flow with water, hoping it'll cool and freeze the front of the flow. Nope, the extreme heat behind the crust, which is still molten, will allow the flow to continue.
Andrews did say that flows can be diverted, but then there's the problem of where the diverted lava goes.
"This problem is most easily illustrated with the example situation where I divert the lava flow to save my house but as a result the lava flow destroys someone else's house," he said. "As a result of these two factors, lava flows are generally not stopped or diverted."
The aftermath
The lava has flowed. The damage is done. Now, there's getting rid of the rock that's left from the flow.
"In most instances the rock is left in place," Andrews said because the volume of rock and the effort required to break it apart and remove it is generally cost-prohibitive.
But sometimes, it needs to be done. Like in October 2014 when the Kilauea volcano erupted, lava crossed over a major road called Cemetery Road, according to County of Hawaii Public Works Department. Crews removed the lava that blocked the roadway and a restoration project began. The solidified lava became an attraction for a while, CNN affiliate KHNL reported in 2015. The project to removed the lava and restore Cemetery Road began in October 2015 and was completed in December 2015. The project, public works said, was completed within the $150,000 budget.
