Kilauea has destroyed 36 structures - including 26 homes - since May 3, when it began releasing lava from vents about 25 miles east of the summit crater.
A summit blast could also release steam and sulfur dioxide gas. The volcano has spewed lava and high levels of sulfur dioxide gas into communities, leading officials to order 1,700 to evacuate.
However, the immediate vicinity around the summit, an area controlled by the National Park Service, was to be closed to visitors indefinitely, starting on Thursday night.
"What we've already been seeing is that chunks of the surrounding vents are just dropping off into the lava and that's why we're getting these small explosions", said Jessica Johnson, a volcanologist at the University of East Anglia in the United Kingdom. One person was killed by falling debris.
Meantime, if rock and other sediment have fallen inward, blocking the steam that's being created, intense pressure builds up.
Those 10-ton projectiles could fly a half-mile from the shield volcano if an explosion occurs, while clouds of ash could blanket areas up to 20 miles away.
Though volcanologists can no longer get close enough to the crater to gather readings, they are using airborne thermal imaging to peer inside.
USGS scientist Tina O'Neal said Friday there are continuing high levels of quake activity and ground activity that suggests magma is still close to the surface.More news: Man Has Eaten 30000 Big Macs, Breaks World Record
Diagram explains explosive eruptions of volcanoes. In February of that year, the lava in Halema'uma'u began draining out of the crater.
Geologists said Kilauea may be entering a new phase of explosive eruptions not seen in almost a century that could hurl "ballistic blocks" weighing up to 12 tons for half a mile (800 meters), and rain pebble-sized fragments for another mile or two (1.8 to 3.2 km). Those types of big blowouts usually take place in stratovolcanoes, steep-sided, cone-shaped volcanoes where pressure builds up in a central vent until the mountain pops in a dramatic explosion.
This event could occur again when the summit lava lake drops so low that groundwater can flow into the conduit that feeds magma to the crater.
"If an explosion happens, there's a risk at all scales".
During almost three weeks of activity, blocks weighing as much as 14 tons were blasted from the crater.
"We know what people are going through in Leilani Estates". "We don't anticipate there being any wholesale devastation or evacuations necessary anywhere in the state of Hawaii".
Lt. Col. Shawn Tsuha, commander of Task Force Hawaii - the military operation to respond to the volcanic outbreak on Hawaii island - said Friday the soldiers and airmen can move more than 200 people at a time in a convoy and that if roads are blocked they can move people by air.