Solomon Islands disaster officials are planning to send emergency supplies to areas after a 6.9 magnitude aftershock yesterday followed Friday's 7.8 shake.
Both quakes triggered tsunami warnings which were lifted a short time later.
Joanne Zoleveke, general secretary of the Solomon Islands Red Cross, said the supply boat could take almost 24 hours to reach Makira Island, which lies close to the epicentre of Friday's magnitude 7.8 quake.
It was followed by a shallow 6.9 tremor about 8am yesterday, and several lighter shakes.
Disaster officials estimated the earthquakes had affected 3712 people and damaged at least 40 houses.
"We are working with the National Disaster Office of the government and we've mobilised our emergency response teams to accompany the government officers and other international non-governmental organisations that are going on this boat," Ms Zoleveke said.
Australia has provided A$50,000 worth of supplies and a helicopter to assess affected areas to help target relief efforts, Zoloveke said.
Makira Island's airstrip services small planes incapable of shuttling the volume of aid required for the relief effort.
Live and Learn country manager Elmah Panisi said there was no major damage caused by Saturday's earthquake, but residents had been keeping alert for further tremors.
"People are bracing their houses and just making sure they are prepared if there is another earthquake," Ms Panisi said.
Friday's quake damaged at least 30 buildings and forced residents to scramble to higher ground.
The remoteness of the region and the failure of communications meant it was impossible to know the full extent of any injuries or damage, Ms Zoloveke said.
She said she knew of only one reported casualty, a 25-year-old with non-specific injuries.
There had not been any other official reports of injury, but some traditional houses in coastal villages on Makira and Malaita were damaged, sometimes by tsunami waves.
Speaking from the capital Honiara, Suzy Sainovski of World Vision said the quake had caused some power failures throughout the country.
Ms Sainovski said staff from the humanitarian organisation in Kirakira saw people fleeing their homes.
"One of the reasons we need to get them shelter assistance [is] because it's the start of the wet season here," she said.
- RNZ / ABC / Reuters