The eruption of the Grimsvotn volcano was far larger than one a year ago at another Icelandic volcano that upended travel plans for 10 million people around the world, but scientists said it was unlikely to have the same widespread effect.

University of Iceland geophysicist Magnus Tumi Gudmundsson said this eruption, which began Saturday, was Grimsvotn's largest eruption for 100 years.  "(It was) much bigger and more intensive than Eyjafjallajokull," the volcano whose April 2010 eruption shut down airspace across Europe for five days, he said.

The ash plunged areas near the volcano in southeast Iceland into darkness Sunday and covered buildings, cars and fields in a thick layer of gray soot. Civil protection workers urged residents to wear masks and stay indoors.

Gudmundsson said the new eruption was 10 times as powerful as the one in 2004, which lasted for several days and briefly disrupted international flights. Grimsvotn also exploded in 1998, 1996 and 1993, eruptions that lasted between a day and several weeks.