Three earthquakes rattled an area northwest of Mount St. Helens on Friday, continuing what geologists say is a mini-swarm of earthquakes not related to the nearby volcano.

The latest quakes, on Friday, were a 3.7-magnitude quake at 2:38 p.m. Friday, followed by a 3.4 at 6:08 and a 3.1 at 6:12 p.m., according to the U.S. Geological Survey.

A report from the USGS on Friday said the quakes have been centered about 13 miles northwest of Mount St. Helens at a depth of about 8 miles. They were described as tectonic in origin and not directly related to the volcano.

The report said such earthquakes are common in areas around Mount St. Helens and Mount Hood. It said another mini-swarm of earthquakes also occurred about six miles southwest of Mount Hood.

Volcano-related seismic activity at the two volcanoes themselves were at normal background levels, the USGS said.