The Indonesian island of Lombok has been hit by a strong earthquake, as it still reels from the impact of Sunday's tremor.
The USGS said the latest quake had a magnitude of 5.9 - there are reports it brought down some buildings.
Officials said the quake's epicentre was on land and so there was no risk of a tsunami.
Rescue workers are still digging through rubble and trying to get aid to victims of the earlier, larger quake.
The Red Cross has said that incident, which killed at least 131 people, was "exceptionally destructive".
Some villages had "completely collapsed", said a Red Cross official in Lombok, Christopher Rassi.
The official death toll stands at 131, but local media are reporting figures as high as 347.
The government says more than 1400 people were injured and more than 156,000 displaced.
The national disaster agency said all those numbers were likely to increase, as more information comes in and more victims were found.
It was not immediately clear whether the latest tremor was a new quake or the strongest of the hundreds of aftershocks to hit since Sunday.
Emergency workers are continuing to dig through rubble and are gradually starting to reach more remote areas of the large island.
But the spokesman for Indonesia's national disaster agency, Sutopo Purwo Nugroho, said some areas in the north had still not received any aid.
Masih pengungsi yang belum tersentuh bantuan untuk korban gempa di Lombok khususnya di Lombok Utara dan Lombok Barat. Kerusakan bangunan masif di Lombok Utara. Perlu upaya keras untuk segera menyalurkan bantuan. pic.twitter.com/nHheUGMLny— Sutopo Purwo Nugroho (@Sutopo_PN) August 8, 2018
Lombok is a roughly 4500 sq km island east of the slightly larger island of Bali.
Most people live in basic housing in small communities. Tens of thousands are now sleeping out in the open or in the ruins of their homes.
"We are still waiting for assessments from some of the more remote areas in the north of the island, but it is already clear that Sunday's earthquake was exceptionally destructive," Mr Rassi said.
"I visited villages yesterday that were completely collapsed," he said, while other teams in East and North Lombok had reported villages where 75 percent of homes were damaged.
With hospitals and clinics also affected, many of the injured have had to be treated in the open air or in makeshift clinics.
Sunday's quake came only days after a slightly smaller one, which killed at least 16 people. There are growing concerns that the important tourism industry will be badly hit at what should be a busy time.
Thousands of tourists visiting Lombok - as well as the nearby Gili Islands and Bali - have been evacuated or have chosen to leave since the weekend.
"We've had light earthquakes in the past, but never anything like this," hotel chain owner Marcel De Rijk told Reuters.
"We've lost a lot of bookings and future guests are in wait-and-see mode. I don't think people will choose Lombok anymore this summer."
The quake struck at 7.46pm local time on Sunday at a fairly shallow depth of 31km.
Indonesia is prone to earthquakes because it lies on the Ring of Fire - the line of frequent quakes and volcanic eruptions that circles virtually the entire Pacific rim.
More than half of the world's active volcanoes above sea level are part of the ring.
- BBC / Reuters