A series of earthquakes and the collapse of the crater floor at Hawaii's most active volcano

A series of earthquakes and the collapse of the crater floor at Hawaii's most active volcano could trigger an eruption, officials have warned. The lava lake at the summit of Kīlauea is one of several persistent on Earth. This image shows how it appeared on the evening of April 11
A series of earthquakes and the collapse of the crater floor at Hawaii's most active volcano could trigger an eruption at any moment, officials have warned.

Lava may burst through the ground east of Kilauea, one of five volcanoes on the US state's largest island, experts say.

The warning follows 250 seismic readings over the past 24 hours, with similar activity recorded prior to previous eruptions in the area.

In mid-April, an observatory issued a volcano activity alert when scientists noticed the Puu Oo vent was inflating and becoming pressurised.

The crater floor of the vent has since collapsed, and an 'intrusion' of lava was sent into a new area of the volcano which spread throughout last night.

Underground magma, which now flows beneath a main road and close to the residential district of Puna, could cause fatalities if it blows.

The warning has been issued by experts from the US Geological Survey's (USGS) Hawaiian Volcano Observatory.

USGS geologist Janet Babb said: 'We knew that change was afoot and we've seen this in the past, and so we have been kind of waiting and watching for whatever change that was going to happen to happen.

'It happened yesterday afternoon.

'Magma has now migrated into a lower part of the East Rift Zone. The concern is that the intrusion migrated about 10 miles (16 km) down rift into the area where Highway 130 is.'

There are homes in that area of the Big Island and Highway 130 leads to a popular access point where people can hike or bike into the lava viewing area.

The Hawaii County Civil Defense Agency sent out an alert Tuesday morning warning residents in the area to monitor the situation and be prepared for the possibility of a new lava flow.

Spokeswoman Kanani Aton said that the agency is 'planning ahead for a worst-case scenario' by reviewing emergency plans and monitoring the activity in conjunction with USGS officials.

All public access from the island's Puna District, near Kalapana, has been shut down and visitors have been warned to stay away in case of an eruption. Private excursions, including boat and hiking tours, have also been suspended.

'It's been closed due to the possibility of an eruption and security has been posted to ensure that no unauthorised persons enter,' Ms Aton said, adding that anywhere from 500 to 2,000 people visit the site each day.

'It is important to note that although there is increased seismic activity in the area, the magnitude is not large enough to cause concern for tsunami.'

Ms Babb says the activity has slowed significantly since a spike on Monday afternoon and overnight, but the threat level has not changed. Scientists don't know if decreased seismic activity is an indication that the event is over or if it's just stalled and could pick back up.

'That's the unknown at this point. Therefore we are still watching, we are watching very closely,' she added.

Geologists flew over the area and observed a layer of red ash covering the ground near the Puu Oo vent. The ash was spread throughout the area when the crater floor collapsed.

'The good news is that as they flew down the East Rift Zone they didn't see any ground cracks or steaming that would suggest that the magma was coming near the surface,' Ms Babb said.

Most of Kilauea's activity has been nonexplosive, but a 1924 eruption spewed ash and 10 ton rocks into the sky, leaving one man dead.

The Mauna Ulu eruption was a five-year-long event at the volcano that lasted from May 24, 1969 until July 22, 1974.

Puu Oo's 1983 eruption resulted in lava fountains soaring over 1,500 feet (460 metres) high. In the decades since, the lava flow has buried dozens of square miles (kilometres) of land and destroyed many homes.

In 2008, after a series of small earthquakes rattled the island, Kilauea's summit crater opened and gushed lava and rock over 75 acres (0.3 sq km) of the mountain, damaging a nearby visitor overlook.