PADANG BAKUNG, Indonesia (Reuters) -- Frightened residents on Indonesia's Sumatra island huddled in tents outside their damaged homes on Friday, traumatized by the latest of more than 40 aftershocks since a huge earthquake struck two days ago.

Indonesia's meteorology agency issued on Friday the latest in a series of tsunami warnings after another strong quake Sumatra.
There have been more than 40 tremors ranging in intensity from 4.9 to 7.8 since Wednesday's 8.4 quake, repeatedly setting off tsunami warnings in Indian Ocean countries.
There have, however, been no reports of the sort of widespread tsunami that caused the death and devastation of the huge waves in 2004, which followed a quake of over 9 magnitude.
At least two areas in Bengkulu province were hit by tsunamis after the quake on Wednesday, residents told Reuters correspondents.
About 100 houses were damaged by a 3 meter (10 ft) wave in Serangai, 70 km north of Bengkulu city, but there were no casualties.
""Suddenly, I heard the rushing sound of water coming, it looked black. So I told everybody to run,"" said Johan, a 60-year-old farmer, who like many Indonesians uses one name. He said most people had already fled to higher ground after the quake.
Some houses had been shifted about 10 meters by the water and tree trunks and large logs littered the main road.
The village of Padang Bakung, two hours drive south of Bengkulu, also suffered a tsunami that inundated houses with water as high as half a meter. The houses were 60 meters from the coast.
""We have a siren, but it doesn't work because of power outages after the quake,"" said village chief Marsan, adding that it could only be heard in a radius of 100 meters anyway.
Marsan, who was dressed in a sarong, said he hoped the government would build breakwaters to shield the village.
""When the quake struck, the sea water spilled onto the streets, reaching the waistline,"" said Jailani, 40, a fisherman.
The latest quakes triggered new panic among thousands camping out in makeshift shelters or tents, using torches and kerosene lights, and setting fires overnight to keep warm.
Wednesday's massive quake and the ensuing aftershocks killed at least 13 people and toppled hundreds of buildings.
Patients had to be moved into tents in front of the hospital in Bengkulu, the nearest major town to the epicenter of Wednesday's 8.4 quake, the most powerful in the world this year.
""When the first strong quake struck, I ran immediately from the room with my infusion,"" said Yasin, 50, who had been treated with an intravenous drip for allergies.
""Last night's quake really terrified me. Although I am outside, I don't feel safe,"" he added, near the damaged Muhammad Yunus hospital, its windows shattered and walls cracked.
One tent had been set up as a temporary emergency unit.
Seismologist Mike Turnbull at Central Queensland University said the region was lucky to have escaped a tsunami similar to the one that killed more than 280,000 people in 2004.
This view was echoed by President Susilo Bambang Yudhoyono, who told reporters on Thursday that damage from the initial quake was ""relatively less"" than feared.
The quakes in the last few days in Sumatra were felt in neighboring Singapore, Malaysia and Thailand.
Rustam Pakaya, head of the Indonesian health ministry's crisis centre in Jakarta, said on Friday that 13 people had been killed and 55 injured across the region since Wednesday's quake.
Roads in the north of Bengkulu province were lined with tents and a Reuters photographer estimated about 8 in 10 houses appeared badly damaged or destroyed.
Indonesia suffers frequent quakes, as it lies on an active seismic belt on the so-called Pacific ""Ring of Fire.