“We are looking at a worst-case scenario,” said Thorvaldur Thordarson, an Icelandic volcanologist. The last time I checked on the volcano in Iceland, one of the nation’s geologists noted that the threat of an eruption had decreased by 90% due to the solidification of magma around the active center of seismic activity near the town of Grindavík. Like many “expert” scientific projections in recent history, this one was less than entirely predictive. Today, about an hour after an earthquake swarm, the fissure volcano erupted about two miles from Grindavik. A volcano in southwestern Iceland began erupting Monday with lava fountains...