MANILA - A restive volcano in the central Philippines spewed a column of ash at least 1 km (0.6 mile) into the sky before dawn on Saturday, raising concern of an eruption in the days ahead. There were two minor explosions of Bulusan volcano in the Bicol region, but there was no sign of laval flow, the Philippine Institute of Volcanology and Seismology said in a statement.Bulusan, one of the six most active volcanoes in the Philippines, has had five ash eruptions since March.