USGS says swarm of earthquakes detected below Mount St. Helens

The U.S. Geological Survey said Friday they have discovered a swarm of small earthquakes underneath Mount St. Helens since March, which could mean it’s recharging with magma.

Scientists said the Pacific Northwest Seismic Network detected more than 130 earthquakes, between 1.2 and 4 miles deep, in the region since March 13. Researchers said the majority of the quakes have registered as a magnitude 0.5 or less and some are too small to detect.

There’s no indication there will be an eruption anytime soon, scientists said.

“No anomalous gases, increases in ground inflation or shallow seismicity have been detected with this swarm, and there are no signs of an imminent eruption,” researchers said. “As was observed at Mount St. Helens between 1987-2004, recharge can continue for many years beneath a volcano without an eruption.”

According to the USGS, the quakes are volcano-tectonic – which are commonly seen in active magma systems. Stress pushes fluid through cracks, creating small quakes or tremors.