For the first time in nearly 40 years, Hawaii`s Mauna Loa, the largest active volcano in the world, is erupting. Lava flows are restricted in the summit area, according to officials, and do not pose a threat to people below. However, the US Geological Service (USGSstatement )`s cautioned that things could change quickly.

 

An ashfall advisory is in effect for Hawaii`s Big Island and the surrounding waters, and residents have been told to remain vigilant. The volcano`s alert level has been upgraded from an "advisory" to a "warning", the highest classification.

 

Mauna Loa last erupted in March and April of 1984, sending lava flows within 8 kilometres of the city of Hilo.

 

The latest eruption began on Sunday night at the volcano`s summit caldera. Calderas are hollows that form beneath the summit at the end of an eruption.

 

It added, if the eruption migrates beyond the walls of the summit caldera, lava flows could "move rapidly downslope.