Mount St Helens appears to be in the very early stages of preparing for another eruption. There have been more than 130 earthquakes detected near the mountain by the Pacific Northwest Seismic Network since March 14th.
The quakes have been small, having, on average, a magnitude of 0.5 or less. The largest tremor reached 1.3. The rate of the quakes has been increasing steadily, but they are too far below the surface to be felt. Geologists say that the earthquakes are indicators that new magma is working its way up into the volcano’s chamber.
However, experts say the likelihood of an eruption happening in the near future is very slim. After its historic eruption in 1980 that killed 57 people, Mount St Helens was surrounded by one of the most elaborate volcanic activity monitoring systems on the globe. Scientists are watching for other signs that a volcano is likely to happen in the near future, signs which have yet to appear.
“The current pattern of seismicity is similar to swarms seen at Mount St. Helens in 2013 and 2014; recharge swarms in the 1990s had much higher earthquake rates and energy release,” said USGS. “No anomalies games, increases in ground inflation or shallow seismicity have been detected with this swarm, and there are no signs of an imminent eruption.”
“The magma chamber is likely imparting its own stresses on the crust around and above it, as the system slowly recharges. The stress drives fluids through cracks, producing the small quakes. The current pattern of seismicity is similar to swarms seen at Mount St. Helens in 2013 and 2014; recharge swarms in the 1990s had much higher earthquake rates and energy release.”