International aid agency World Vision is responding to the 7-magnitude earthquake which struck Indonesia's Lombok Island on Sunday.

The death toll topped 100 on Tuesday as rescuers found victims under wrecked buildings, while thousands left homeless in the worst-affected areas waited for aid to arrive.

'Many people have been forced to flee their homes because of the numerous aftershocks,' said Margaretha Siregar of World Vision Indonesia.

'World Vision has already got equipped and trained staff in the field conducing initial assessments to identify the immediate needs of the affected displaced children and their families. We will continue to mobilise the response with local partners and plan to focus on child protection, clean water, sanitation and hygiene and making sure children have access to education in the aftermath of the crisis,' she said.

A woman was pulled alive from the rubble of a collapsed grocery store in the north, near the epicentre of Sunday's 6.9 magnitude quake, the second tremor to rock the tropical island in a week.

That was a rare piece of good news as hopes of finding more survivors faded and a humanitarian crisis loomed for thousands left homeless by the disaster in the rural area and in desperate need of clean water, food, medicine and shelter.

Sutopo Purwo Nugroho, the spokesman of Indonesia's disaster mitigation agency (BNPB) put the toll at 105, including two on the neighbouring island of Bali to the west, where the quake was also felt – and the figure was expected to rise.

Approximately one million people live near the epicentre and there have been more than 100 aftershocks. The BNPB stated that the number of victims is expected to increase.

The earthquake is the second to strike the region in recent days. A 6.4 magnitude earthquake struck Lombok Island on July 29, killing 16 people and injuring hundreds more.

'World Vision distributed over 360 tarps on Saturday, the day before the magnitude-6.9 earthquake hit, because many people have already been staying outside after the first earthquake last week. After yesterday's earthquake, that need for emergency shelter has significantly increased, especially as these aftershocks continue,' Siregar said.

Sunday's earthquake was felt in Bali, Sumbawa and Surabaya. The overall impact is still under assessment.

There has been little government relief for the area, where the greatest need is for water and food, as underground water sources have been blocked by the quake and shops destroyed or abandoned.

About 75 per cent of the north has been without electricity since Sunday, officials said, and some communities were hard to reach because bridges were damaged and trees, rocks and sand lay across roads cracked wide open in places by the tremor.

Aid agency Oxfam said it was providing clean drinking water and tarpaulin shelters to 5,000 survivors, but the need was much greater, with more than 20,000 estimated to have been displaced.'Thousands ... are under open skies in need of drinking water, food, medical supplies, and clothes,' it said in a statement. 'Clean drinking water is scarce due to the extremely dry weather.'

Thousands of tourists have left Lombok since Sunday evening, fearing further earthquakes, some on extra flights added by airlines and some on ferries to Bali.

Officials said about 4,600 foreign and domestic tourists had been evacuated from the three Gili islands off the northwest coast of Lombok, where two people died and fears of a tsunami spread soon after the quake.

World Vision has opened an Indonesian earthquake fund. 

Addtional reporting by Reuters.