The shallow quake hit at 0612 GMT Wednesday about 500 miles southwest of Anchorage, and around 60 miles south-southeast of the remote settlement of Perryville, the US Geological Survey said.
The quake struck at 5.54 am with the epicentre at 53 km northwest Jepara of the province and a depth of 578 km under the sea bed.
The quake did not trigger a tsunami, the official said.
The tremor felt on Thursday afternoon with the epicentre at 89 km northwest Daruba village of Pulau Marotai district and the depth at 112 km under sea bed.
Many others were not able to return to their families, with ferries and plane services suspended.
The Whakaari volcano - visited by more than 17,500 people in 2018 - erupted as the alert level was two on a scale of five, predicting mild volcanic activity.
There was no immediate reports of damages or casualties.
The strong quake was felt in the capital Jakarta and people rushed out of high-rise buildings.
The quake has only caused minor damages in Nusa Dua so far and there was no immediate report of casualties.
Mt Agung became active in September 2017 and its eruptions have forced operations at Denpasar airport to be halted many times.
