JAKARTA - Over 21,800 people sought refuge at 33 shelters in Karo district of North Sumatra province as the Sinabung volcano continued to spew ash and lava on Monday, an Indonesian official said.

The volcano was recorded to have erupted for 115 times since Saturday and more than 1,500 tremors have occurred, National Disaster Mitigation Agency (BNPB) spokesperson Sutopo Purwo Nugroho said.

"The intensive volcanic quakes indicate that magma supply to the crater was still actively going on," Sutopo told Xinhua.

He added that hot ash cloud would emerge and likely to flow to the east and southeast within a radius of 4 to 5 kilometers of the crater.

Sutopo added that rain of small volcanic stones with maximum diameter of 6 centimeters occurred within a radius of 5 kilometers.

The volcano with a height 2,460 meters above the sea level has rumbled to life since September last year after being dormant for 400 years, the volcano has erupted on and off since then.

The volcano on Saturday started shooting ash to the air in a new spate, according to Sutopo.  

Hence, the authorities extended emergency relief period ended on January 5 to January 18, he said.  

On December 31 last year, Mount Sinabung erupted, spewing ash 7000 meters to the sky, one of the strongest since September.

The Mount Sinabung is among the 129 active volcanoes in the vast archipelago country.