Strong earthquake strikes off Indonesia's Java island, no tsunami risk

A strong earthquake of magnitude 6.6 struck deep off of Indonesia's Java island on Friday, but there was no risk of tsunami, the country's geophysics agency said.

The quake had a depth of 632km, the agency said, with aftershocks felt about 20 minutes later of a magnitude of 5.5.

The quake was felt in the urban centres of Surabaya, Tuban, Semarang and Bali's Denpasar, according to the disaster agency.

The European-Mediterranean Seismological Centre (EMSC) put the magnitude of the initial quake at 6.5 with a depth of 592km.

Abdul Muhari, spokesperson for the national disaster agency, said:

Indonesia straddles the so-called "Pacific Ring of Fire", a highly active seismic zone, where different plates on the Earth's crust meet and create a large number of earthquakes and volcanoes.

A staff member at the Mustika Hotel in Tuban told Reuters by phone the tremors were lightly felt and no damage was reported.

An employee at the JW Marriott hotel in Surabaya said the quake was felt strongly there, causing panic amongst guests.

"All the guests went out from their rooms and were going outside the hotels. But no damage," the employee said by phone.