Fears an Icelandic volcano will erupt remain high as magma spreads underground and huge cracks appear in the roads of a town most at risk.
Seismic activity in southwestern Iceland decreased in size and intensity on Monday, but the risk of a volcanic eruption remained significant, authorities said.
Around 900 earthquakes hit the south of the country on Monday, with tens of thousands of tremors reported in the region of Reykjanes in recent weeks.
Almost 4,000 people were evacuated from Grindavik over the weekend as authorities feared that molten rock would rise to the surface of the earth and potentially hit the coastal town and a geothermal power station.
On Tuesday authorities scrambled to build a defence wall around the Svartsengi power plant, located just over six kilometers from Grindavik, to protect it from lava flows amid fears of an eruption.