JAKARTA, April 22 (Xinhua) -- Six people were wounded in Central Java province of central Indonesia by a very shallow aftershock of a 4.4-magnitude earthquake, a disaster agency official said on Sunday.
Spokesman of national disaster management agency Sutopo Purwo Nugroho said that one of the injured suffered very serious injury.
"Risk assessment is still underway as many houses have been devastated," he said.
An official of the meteorology and geophysics agency told Xinhua by phone that a 3.4-magnitude aftershock with a depth of 1 km has jolted Banjarnegara district.
The main shock of 4.4 magnitude with a depth of 4 km struck off the province on Thursday, leaving two people dead, 21 others injured and more than 3,500 people displaced, according to the agencies.
More than 600 soldiers, police, personnel of the Red Cross, search and rescue office, disaster agency and volunteers have been undertaking relief efforts in the quake-affected areas, according to the disaster agency.
Indonesia is prone to quake as it lies on a vulnerable zone of so-called "the Pacific Ring of Fire".
