A Hawaiian volcano is blasting out "ballistic blocks" the size of kitchen appliances and the authorities are warning it could get worse.
Mount Kilauea erupted almost two weeks ago, with lava destroying dozens of homes and forcing hundreds of people to be evacuated.
An ash plume rising up to two miles (more than 3,000m) prompted officials to warn pilots to avoid the area.
Quakes as strong as magnitude 4.4 have been felt on the largest island.
The floor of the volcano's caldera (the bowl where lava erupts) is deflating, causing stress at the volcano's base.
This is causing earthquakes and new fissures to open in the ground, and creating the risk of new, highly explosive steam-powered eruptions as the magma meets underground water.
The ash plume can be seen from the International Space Station.
Boulders of up to 2ft (60cm) were found a few hundred yards from the crater, reported the US Geological Survey's Hawaiian Volcano Observatory.
But it warned things could get much more dangerous.
"During steam-driven explosions, ballistic blocks up to 2m (yards) across could be thrown in all directions to a distance of 1 km (0.6 miles) or more," it said.
"These blocks could weigh a few kilograms (pounds) to several tons. Smaller (pebble-size) rocks could be sent several kilometers... mostly in a downwind direction."
Lava, earthquakes and projectiles are not the islanders' only concerns:
Vog - volcanic air pollution - contains sulphur dioxide which can cause breathing problems and irritate the eyes
Ash - the area is already dusted with volcanic ash but authorities say this could get worse, posing risks to human and animal health, agriculture and power and water supplies
Disrupted transport links - a red aviation code has been issued, a warning to pilots to avoid the potentially damaging ash cloud. Hawaii is one of the world's most isolated population centres