Eyewitness: Fire fountains spout molten rock and lava sweeps towards people's homes
By Thomas Moore, science correspondent in Iceland
Stand on the hill overlooking the eruption site and you see how perilously close it is to Grindavik.
A search and rescue team had taken us into the exclusion zone, past the Blue Lagoon spa, towards the evacuated town.
From our vantage point we could see fire fountains spouting molten rock and lava sweeping towards people's homes.
The eruption has subsided overnight.
It's nothing like the curtain of fire videoed by the coastguard helicopter on Sunday.
We saw three fire fountains. One was spouting lava a good 5m into the air; the other two were smaller.
The lava doesn't seem to be moving now, but it is glowing red hot in places. Steam and smoke rise into the chilly winter air.
But the lava has already caused considerable damage, severing the pipes that took hot water from the nearby power station into the town.
It means homes have no heat. And at this time of year that makes them uninhabitable.
Engineers are assessing how the pipes might be rerouted, but that will take a while.
The defensive wall that workers have been building over the last fortnight has prevented more considerable damage to the town.
It's about 3m high, built from rock and earth. And it has diverted much of the lava flow.
It's the first time it has ever been tried and it worked.
The wall hasn't been finished though, and where it was slightly lower it was overtopped by lava.
The second fissure, which opened up much closer to town, inside the defensive wall, took everyone by surprise.
There was nothing to stop the lava, but fortunately only three houses appear to have been consumed by the molten rock or burned by the intense heat.
Civil defence teams are now taking stock of the situation.
If the eruption is petering out already then repairs can start.
But whether the people of Grindavik want to return to their homes when lava is looming on their doorstep is another matter.