Two small explosions at Halema'uma'u's fuming vent and spectacular fountaining in a lava flow inside Royal Gardens subdivision marked an increase in activity Monday and yesterday at Kilauea volcano.

In addition, the latest measurement of sufur dioxide spewing from Pu'u 'O'o soared to 4,800 tons a day, well above normal.

The flow inside Royal Gardens that threatened one of the subdivision's remaining structures evidently picked up vigor because the lava tube that had been transporting molten rock from the Pu'u 'O'o area to the ocean at Waikupanaha has become blocked upslope, halting the flow into the sea.

Jim Kauahikaua, Hawaiian Volcano Observatory scientist in charge, said scientists plan to fly over the flow area tomorrow, unless changes in conditions require an earlier flight.

The Royal Gardens subdivision has been overrun a number of times since the eruption began on Jan. 3, 1983. The most recent surface breakout occurred in February.

"This is only the latest of many, many lava flows through Royal Gardens," Kauahikaua said.

The small explosions at the fuming vent in Halema'uma'u blew out rock ash, contrasted with the mostly volcanic glass that had been showing up in collection areas. One of the explosions, just after midnight yesterday, sent what looked like a red flame flashing across the vent, the Volcano Observatory Web site said.

During the day yesterday, the usual white plume rose from the summit vent as swarms of earthquakes were registered on the instruments inside the observatory.