A magnitude 6.4 earthquake struck the island of Lombok in Indonesia, the US Geological Survey said.
The quake, which struck at 6.47am local time on Sunday, was followed less than an hour later by a 5.4 magnitude aftershock in the same area.
The epicentre was 80 miles northeast of the islands main city of Mataram and was very shallow, which would have amplified its effect.
The earthquake was on land and did not trigger any waves or tsunami but authorities issued a yellow alert, suggesting there was a possibility of casualties.
A 6.4 magnitude is strong enough to cause injuries and damage to buildings, but largely depends on how densely populated the affected area is.
In February, an earthquake of that strength hit Taiwan, killing 17 people and injuring hundreds more.
The European-Mediterranean Seismological Centre (EMSC), the European quake agency, put the latest quake in Lombok at magnitude 6.5.
Indonesia is prone to earthquakes due to its location on the Pacific "Ring of Fire", an arc of volcanoes and fault lines in the Pacific Basin.
In December 2004, a massive magnitude-9.1 earthquake off Sumatra triggered a tsunami that killed 230,000 people in a dozen countries.
Lombok is an Indonesian island east of Bali popular with tourists.
The Foreign Office currently has a travel warning related to nearby volcanic activity.
Travellers are advised to avoid the Mount Agung crater in east Bali and the Mount Sinabung crater in Kalo Regency, North Sumatra.
On the topic of earthquakes in Indonesia, the Foreign Office advises: "If a major earthquake or landslide occurs close to shore, you should follow the instructions of local authorities, bearing in mind that a tsunami could arrive within minutes.
"The Indonesia Tsunami Early Warning Centre issues tsunami warnings when a potential tsunami with significant impact is imminent or expected."
