HONOLULU -- A second explosion blasted the recently opened vent in Halema`uma`u Crater late on Wednesday night, according to scientists at Hawaiian Volcano Observatory.

It happened at about 11:08 p.m.

The explosion was smaller in magnitude than the one on March 19. It widened the vent by 15 to 30 feet, according to U.S. Geological Survey scientists who have been monitoring the crater around the clock.

The scientists saw rocks shooting out from the vent during the explosion. Some of the rocks soared about 230 feet to the rim of the crater. They also said that a faint glow returned to the vent a few minutes after the explosion.

Geologists found lava splatter and debris when they investigated the explosion on the crater rim in the morning.

Scientists said it appears that Wednesday night's explosion did not eject nearly as much material as the explosion on March 19.

The Halema`uma`u vent continued to erupt a white plume of ash and sulfur dioxide on Thursday.