A volcanic eruption that has started under the Eyjafjalla glacier in southern Iceland on Wednesday is much more powerful than one that took place last month, according to reports from Reykjavik.

The eruption melted ice and shot smoke and steam thousands of meters into the air. It also forced the closure of a major road and forced hundreds of people to flee rising floodwaters.

Information gathered from scientists aboard a Coast Guard plane that flew over the volcano indicated that the total length of the fissure is about two kilometers, the Icelandic national broadcaster RUV reported. The new eruption appears to be about nine kilometers west of the fissure that developed last month.

Massive flooding has started on the Markarfljot river in the area. Roads and bridges are considered to be in danger.

"Both sides of the glacier are flooded. It appears to be a very powerful flood," Vidir Reynisson, who manages the Icelandic Civil Protection Department, was quoted as saying by the online Iceland Review.

Reynisson said that it was important that people do not drive along the main coastal ring road near the volcano.

No air traffic was allowed in a large area above and around the eruption site. The no flight zone could affect routes to and from Norway, even Russia later Wednesday, RUV reported.

On Wednesday morning, about 800 people were evacuated from their homes near the volcano because of the risk of eruption.

The volcano, about 120 kilometers east of Reykjavik, erupted March 20 after almost 200 years of silence.

Iceland, a nation of 320,000 people, sits on a large volcanic hot spot in the Atlantic's mid-oceanic ridge. Volcanic eruptions are often triggered by seismic activity when the Earth's plates move and when magma from deep underground pushes its way to the surface.