PORTLAND — The tsunami that killed 230,000 people in 2004 was the biggest in the Indian Ocean in about 600 years, and it has lessons for the Pacific Northwest, geologists said Wednesday.

Geologists say the long gap between tsunamis in the Indian Ocean might explain the buildup in geologic forces that triggered the huge undersea earthquake and launched the killer waves four years ago, the journal Nature said.

In the American Northwest, too, many centuries typically pass between catastrophic quakes and tsunamis, which are likely to recur in the region, geologists at a news conference said.

They called for greater public awareness, not just in coastal towns but also among tourists.