Scientists using underwater listening devices have detected a swarm of earthquakes off the coast of the central part of Oregon.

Scientists say they don’t know what the earthquakes mean. They said the quakes could be the result of magma boiling under the Juan de Fuca Plate, which is away from the normally recognized earthquake areas off Oregon’s coast.

There have been more than 600 quakes over the past 10 days in a basin 150 miles southwest of Newport, reports said.

Geophysicist Robert Dziak of the National Oceanic and Atmospheric Administration and Oregon State University’s Hatfield Marine Science Center in Newport, Ore., says the quake pattern looks like what happens before a volcanic eruption – only there are no volcanoes in the area, he added.