Hawaii's Mauna Loa volcano spewing lava and ash

From the window of a helicopter, streams of lava can be seen snaking down from the crater of Mauna Loa in Hawaii's Volcanoes National Park. The biggest volcano in the world last erupted in 1984. It's still unclear how the situation will develop, and whether the lava is likely to reach populated areas.

Sightseers on Hawaii Island watch the Mauna Loa eruption from the nearby town of Hilo. The authorities say that as things stand local population centers are not in danger. Vulcanologists had been anticipating an eruption after registering a series of earthquakes on the mountain.

Fountains of lava shoot from a fissure in the Northeast Rift Zone. Some people venture closer to the crater in search of sensational photos — this is a unique natural spectacle, after all — but, in doing so, they're taking quite a risk. For now, the lava is flowing in a different direction, but a bigger eruption could happen at any time, which would send rocks flying into the air.

The light given off by the streams of lava paints beautiful colors on the sky, as thick clouds of smoke blow over the landscape. When the volcano erupted in 1950, the lava flow took just three hours to reach the sea, 24 kilometers (14.5 miles) away.

A woman watches the Mauna Loa eruption from a safe distance. Although the surrounding towns are not currently in danger, Hawaii's Civil Defense Agency announced that shelters have been opened in Kailua-Kona and Pahala.

Helicopters are flying over the volcano, which is being closely observed from the air, so officials can react swiftly if the situation changes. Mauna Loa is 4,169 meters (13,758 feet) high, and lava can flow down its steep slopes extremely fast.

The thick clouds of smoke are expected to bring ash rain. The US National Weather Service has predicted that it will soon fall here on Big Island, the main island in the Hawaiian archipelago. Some areas could be covered in a blanket of ash up to 0.6 centimeters (0.235 inches) thick. No one knows how long the volcano might go on spitting fire.