The Icelandic Meteorological Office said the eruption began just before 8:00 a.m. local time Sunday about a half mile from the town of Grindavík after a series of intense earthquakes.
The severe weather has canceled hundreds of flights, knocked out power for hundreds of thousands of households and disrupted campaigning in Iowa ahead of Monday's caucuses.
Authorities in Idaho on Friday located and retrieved the body of a man who was caught in an avalanche while backcountry skiing with two other men who were rescued the previous day.
Storms dropped as much as 12 inches of snow across the Midwest. Across the South, storms brought heavy rain, hail, tornadoes and flash floods to parts of Alabama, Florida, Georgia and the Carolinas.
The storm caused deaths and damage in the Southeast and stranded motorists on highways in the Midwest. It is expected to bring heavy rain to the Northeast, parts of which got a foot of snow on Sunday.