Scientists monitoring seismic activity in East New Britain province of Papua New Guinea say a tsunami last week shows their equipment is insufficient to warn people.
Ima Itikarai of the Rabaul Volcanological Observatory says a powerful earthquake on Friday generated a small tsunami in Rabaul harbour, which was detected by two tide gauges.
Mr Itikarai says a tsunami could reach every part of Papua New Guinea before wave information could be received from their gauges and relayed to the capital, Port Moresby.
Officials confirm the quake on Friday destroyed a house in Buka in Bougainville, where foodstuffs were shaken off the shelves of local shops.
No-one was hurt.